document_title: Spawn (biology)

question_text: how many eggs the fish produces each time

question_tokens: how many eggs the fish produces each time

text: Spawn (biology)

text: Overview[edit]

text: Marine animals, and particularly bony fish, commonly reproduce by broadcast spawning. This is an external method of reproduction where the female releases many unfertilised eggs into the water. At the same time, a male or many males release a lot of sperm into the water which fertilises some of these eggs. The eggs contain a drop of nutrient oil to sustain the embryo as it develops inside the egg case. The oil also provides buoyancy, so the eggs float and drift with the current. The strategy for survival of broadcast spawning is to disperse the fertilised eggs, preferably away from the coast into the relative safety of the open ocean. There the larvae develop as they consume their fat stores, and eventually hatch from the egg capsule into miniature versions of their parents. To survive, they must then become miniature predators themselves, feeding on plankton. Fish eventually encounter others of their own kind (conspecifics), where they form aggregations and learn to school.

text: Internally, the sexes of most marine animals can be determined by looking at the gonads. For example, male testes of spawning fish are smooth and white and account for up to 12% of the mass of the fish, while female ovaries are granular and orange or yellow, accounting for up to 70% of the fish's mass. Male lampreys, hagfish and salmon discharge their sperm into the body cavity where it is expelled through pores in the abdomen. Male sharks and rays can pass sperm along a duct into a seminal vesicle, where they store it for a while before it is expelled, while teleosts usually employ separate sperm ducts.[4]:141

text: Externally, many marine animals, even when spawning, show little sexual dimorphism (difference in body shape or size) or little difference in colouration. Where species are dimorphic, such as sharks or guppies, the males often have penis-like intromittent organs in the form of a modified fin.[4]:141

text: A species is semelparous if its individuals spawn only once in their lifetime, and iteroparous if its individuals spawn more than once. The term semelparity comes from the Latin semel, once, and pario, to beget, while iteroparity comes from itero, to repeat, and pario, to beget.

text: Semelparity is sometimes called "big bang" reproduction, since the single reproductive event of semelparous organisms is usually large and fatal to the spawners.[5] The classic example of a semelparous animal is the Pacific salmon,which lives for many years in the ocean before swimming to the freshwater stream of its birth, spawning, and then dying. Other spawning animals which are semelparous include mayflies, squid, octopus, smelt, capelin and some amphibians.[6] Semelparity is often associated with r-strategists. However, most fish and other spawning animals are iteroparous.

text: When the internal ovaries or egg masses of fish and certain marine animals are ripe for spawning they are called roe. Roe from certain species, such as shrimp, scallop, crab and sea urchins, are sought as human delicacies in many parts of the world. Caviar is a name for the processed, salted roe of non-fertilized sturgeon. The term soft roe or white roe denotes fish milt. Lobster roe is called coral because it turns bright red when cooked. Roe (reproductive organs) are usually eaten either raw or briefly cooked.

text: "The reproductive behaviour of fishes is remarkably diversified: they may be oviparous (lay eggs), ovoviparous (retain the eggs in the body until they hatch), or viviparous (have a direct tissue connection with the developing embryos and give birth to live young). All cartilaginous fishes—the elasmobranches (e.g., sharks, rays, and skates)—employ internal fertilization and usually lay large, heavy-shelled eggs or give birth to live young. The most characteristic features of the more primitive bony fishes is the assemblage of polyandrous (many males) breeding aggregations in open water and the absence of parental care..."[7]

text: There are two main reproduction methods in fish. The first method is by laying eggs and the second by live-bearing (producing their young alive).

text:
In the first method, the female fish lays eggs either on the sea floor or on the leaves of an aquatic plant. A male fish fertilizes the eggs, and both then work together to protect the eggs/babies from danger until they can defend themselves.
In the second method, the male fish uses its anal fin to transmit sperm into the female fish and fertilize the fish eggs. Later, the female gives live birth to her fry.

text: Sexual strategies[edit]

text: Basic strategies[edit]

text:
The four basic mating systems[4]:160–161[8]

Single female
Multiple females

Single male
Monogamy
Polygyny

Multiple males
Polyandry
Polygynandry

text: Monogamy occurs when one male mates with one female exclusively. This is also called pair spawning.[9] Most fish are not monogamous, and when they are, they often alternate with non-monogamous behaviours. Monogamy can occur when feeding and breeding grounds are small, when it is difficult for fish to find partners, or when both sexes look after the young.[8] Many tropical cichlids, which rear their young together in locations where they must fiercely defend against competitors and predators are monogamous.[10] "In some pipefishes and seahorses, development of eggs takes a long time before the female can place them in the brood pouch of a male, where they are fertilized. While the male is pregnant, the female starts a new batch of eggs, which are ready at about the same time that the male gives birth to the young from the previous mating. This close timing of development promotes monogamy, especially if the likelihood of encountering another potential mate is low."[8]

text: Polygyny occurs when one male gets exclusive mating rights with multiple females. In polygyny a large conspicuous male usually defends females from other males or defends a breeding site.[8] The females choose large males that are successfully defending prime breeding sites which the females find attractive. For example, sculpin males defend "caves" underneath rocks which are suitable for the incubation of embryos.

text: Another way males get to mate with several females is through the use of leks. Leks are places where many fish come together, and the males display to each another. Based on these displays, each female then selects the male they want to be their mate. For example, among the cichlid Cyrtocara eucinostomus in Lake Malawi, up to 50,000 large and colourful males display together on a lek four kilometres long. The females, which are mouth brooders, choose which male they want to fertilize their eggs.[11]

text: Polyandry occurs when one female gets exclusive mating rights with multiple males. This is not common, but it does happen among fish like clownfish that change their sex. It can also happen when males do the brooding but can cannot handle all the eggs the female produce, such as with some pipefish.[4]:161

text: The males in some deep sea anglerfishes are much smaller than the females. When they find a female they bite into her skin, releasing an enzyme that digests the skin of their mouth and her body and fusing the pair down to the blood-vessel level. The male then slowly atrophies, losing first his digestive organs, then his brain, heart, and eyes, ending as nothing more than a pair of gonads, which release sperm in response to hormones in the female's bloodstream indicating egg release. This extreme sexual dimorphism ensures that, when the female is ready to spawn, she has a mate immediately available.[12] A single anglerfish female can "mate" with many males in this manner.

text: Polygynandry occurs when multiple males mate indiscriminately with multiple females. This mutual promiscuity is the approach most commonly used by spawning animals, and is perhaps the "original fish mating system."[4]:161 Common examples are forage fish, such as herrings, which form huge mating shoals in shallow water. The water becomes milky with sperm and the bottom is draped with millions of fertilized eggs.[4]:161

text: Cuckoldry[edit]

text: Alternate male strategies which allow small males to engage in cuckoldry can develop in species where spawning is dominated by large and aggressive males. Cuckoldry is a variant of polyandry, and can occur with sneak spawners (sometimes called streak spawners). A sneak spawner is a male that rushes in to join the spawning rush of a spawning pair.[13] A spawning rush occurs when a fish makes a burst of speed, usually on a near vertical incline, releasing gametes at the apex, followed by a rapid return to the lake or sea floor or fish aggregation.[14] Sneaking males do not take part in courtship. In salmon and trout, for example, jack males are common. These are small silvery males that migrate upstream along with the standard, large, hook-nosed males and that spawn by sneaking into a redd (spawning nest) to release sperm simultaneously with a mated pair. This behaviour is an evolutionarily stable strategy for reproduction, because it is favoured by natural selection just like the "standard" strategy of large males.[15]

text: Cuckoldry occurs in many fish species, including dragonets, parrotfishes and wrasses on tropical reefs and the bluegill sunfish in fresh water. Sneaker males that become too large to hide effectively become satellite males. With bluegill sunfish, satellite males mimic the behaviour and colouration of the females. They hover over a nest containing a pair of courting sunfish, and gradually descend to reach the pair just as they spawn. Males may need to be 6 or 7 years old to function capably as parental males, but may be able to function as sneaker or satellite males when they are as young as 2 or 3 years old. The smaller satellite and sneaker males may get mauled by the more powerful parental males, but they spawn when they are younger and they do not put energy into parental care.[4]:161–2[16]

text: Hermaphroditism[edit]

text: Hermaphroditism occurs when a given individual in a species possesses both male and female reproductive organs, or can alternate between possessing first one, and then the other. Hermaphroditism is common in invertebrates but rare in vertebrates. It can be contrasted with gonochorism, where each individual in a species is either male or female, and remains that way throughout their lives. Most fish are gonochorists, but hermaphroditism is known to occur in 14 families of teleost fishes.[17]

text: Usually hermaphrodites are sequential, meaning they can switch sex, usually from female to male (protogyny). This can happen if a dominant male is removed from a group of females. The largest female in the harem can switch sex over a few days and replace the dominant male.[17] This is found amongst coral reef fishes such as groupers, parrotfishes and wrasses. It is less common for a male to switch to a female (protandry).[4]:162 As an example, most wrasses are protogynous hermaphrodites within a haremic mating system.[18][19] Hermaphroditism allows for complex mating systems. Wrasses exhibit three different mating systems: polygynous, lek-like, and promiscuous mating systems.[20] Group spawning and pair spawning occur within mating systems. The type of spawning that occurs depends on male body size.[19] Labroids typically exhibit broadcast spawning, releasing high amounts of planktonic eggs, which are broadcast by tidal currents; adult wrasses have no interaction with offspring.[21] Wrasse of a particular subgroup of the Labridae family Labrini do not exhibit broadcast spawning.

text: Less commonly hermaphrodites can be synchronous, meaning they simultaneously possess both ovaries and testicles and can function as either sex at any one time. Black hamlets "take turns releasing sperm and eggs during spawning. Because such egg trading is advantageous to both individuals, hamlets are typically monogamous for short periods of time–an unusual situation in fishes."[22] The sex of many fishes is not fixed, but can change with physical and social changes to the environment where the fish lives.[23]

text: Particularly among fishes, hermaphroditism can pay off in situations where one sex is more likely to survive and reproduce, perhaps because it is larger.[24] Anemone fishes are sequential hermaphrodites which are born as males, and become females only when they are mature. Anemone fishes live together monogamously in an anemone, protected by the anemone stings. The males do not have to compete with other males, and female anemone fish are typically larger. When a female dies a juvenile (male) anemone fish moves in, and "the resident male then turns into a female and reproductive advantages of the large female–small male combination continue".[25] In other fishes sex changes are reversible. For example, if some gobies are grouped by sex (male or female), some will switch sex.[4]:164[24]

text: Unisexuality[edit]

text: Unisexuality occurs when a species is all-male or all-female. Unisexuality occurs in some fish species, and can take complex forms. Squalius alburnoides, a minnow found in several river basins in Portugal and Spain, appears to be an all-male species. The existence of this species illustrates the potential complexity of mating systems in fish. The species originated as a hybrid between two species, and is diploid, but not hermaphroditic. It can have triploid and tetraploid forms, including all-female forms that reproduce mainly through hybridogenesis.[26]

text: It is rare to find true parthenogenesis in fishes, where females produce female offspring with no input from males. All-female species include the Texas silverside, Menidia clarkhubbsi[27] as well as a complex of Mexican mollies.[4]:162 Parthenogenesis has been recently observed in hammerhead sharks[28] and blacktip sharks.[29] It is also known to occur in crayfish[30][31] and amphibians.[32][33]

text: Spawning strategies[edit]

text: This section is patterned after a classification of the spawning behaviours of fish by Balon (1975, 1984) into reproductive guilds. This classification is based on how the eggs are fertilized (internal or external spawners), where the eggs are deposited (pelagic or benthic spawners), and whether and how the parents look after the eggs after spawning (bearers, guarders and nonguarders).[34]

text: Nonguarders[edit]

text: Nonguarders do not protect their eggs and offspring after spawning

text: Open substrate spawners[edit]

text:
Nonguarders: Open substrate spawners[34]

Pelagic spawners
Benthic spawners

Spawners on coarse bottoms

Pelagic free embryo and larvae
Benthic free embryo and larvae

Spawners on plants

Obligatory
Nonobligatory

Spawners on fine substrates

Terrestrial spawners

Pike usually spawn on vegetation flooded by high water. Their eggs adhere to the stems of plants.

tag: div

text:
Nonguarders: Brood hiders[34]

Benthic spawners
Crevice spawners
Spawners on invertebrates
Beach spawners

Bitterlings transfer responsibility for the care of their young to mussels. This male bitterling is exhibiting spawning colours

text: Open substrate spawners scatter their eggs in the environment. They usually spawn in shoals without complex courtship rituals, and males outnumber females.

text: Broadcast spawners: release their gametes (sperm and eggs) into open water for external fertilisation. There is no subsequent parental care.[35] About 75% of coral species are broadcasters, the majority of which are hermatypic, or reef-building corals.[36]

text:
Pelagic spawners: a type of broadcast spawners, spawn in the open sea, mostly near the surface. They are usually pelagic fish such as tuna and sardines. Some demersal fish leave the bottom to spawn pelagically, particularly coral reef fish such as parrotfish and wrasses. Pelagic spawning means water currents widely disperse the young. The eggs, embryos and larvae of pelagic spawners contain oil globules or have a high water content. As a result, they are buoyant and are widely dispersed by currents. The downside is that mortality is high, because they can be eaten so easily by pelagic predators or they can drift into unsuitable areas. Females compensate by spawning large numbers of eggs and extending their spawning periods. Pelagic spawners that live in or around coral reefs can spawn a small number of eggs almost daily over a period of months. These fishes have complex breeding behaviours including sex changes, harems, leks and territoriality.[4]:143 See also: Coral reef fish.
Benthic spawners: deposit their spawn on or near the bottom of the sea (or lake). They are usually demersal fish such as cod and flatfish. These species typically spawn without ceremony; they do not engage in elaborate courtship rituals. Each female is usually followed by several males who fertilize the eggs as they are released. Various strategies ensure the eggs and embryos remain in place, and do not drift with the current. The eggs can adhere to other eggs or to whatever they are deposited on, or the eggs can be laid in long strings which are wrapped around plants or rocks. Some eggs take on water after they are released, so they can be dropped into cracks where they swell and wedge themselves in place.

Egg scatterers: scatter adhesive or non-adhesive eggs to fall to the substrate, into plants, or float to the surface. These species do not look after their brood and even eat their own eggs. These are often schooling fish which spawn in groups or pairs, often laying a large number of small eggs. The fry hatch quickly.
Egg depositers: deposit eggs on a substrate (tank glass, wood, rocks, plants). Egg depositors usually lay fewer eggs than egg-scatterers, although the eggs are larger. Egg depositors fall into two groups: those that care for their eggs, and those that do not. Among egg depositors that care for their eggs are cichlids and some catfish. Egg depositors that care for their young can be divided into two groups: cavity spawners and open spawners.
Cavity spawners: lay eggs in a cave or cavity. These fish form pairs and have advanced brood care where the eggs are defended and cleaned. The eggs take a few days to hatch, and the fry are often guarded by the parents. Various catfish, Cyprinidae, and killifish make up the majority. Cavity spawners can be contrasted with open (shelter) spawners, which lay their eggs on an open surface.

text: Brood hiders[edit]

text: Brood hiders hide their eggs but do not give parental care after they have hidden them. Brood hiders are mostly benthic spawners that bury the fertilized eggs. For example, among salmon and trout the female digs a nest with her tail in gravel. These nests are called redds. The female then lays her eggs while the male fertilizes them, while both fish defend the redd if necessary from other members of the same species. Then the female buries the nest, and the nest site is abandoned. In North America, some minnows build nests out of piles of stones rather than dig holes. The minnow males have tubercles on their head and body which they use to help them defend the nest site.[4]:145

text: Egg buriers - can inhabit waters that dry up at some time of the year. An example are annual killifish which lay their eggs in mud. The parents mature quickly and lay their eggs before dying when the water dries up. The eggs remain in a dormant stage until rains stimulate hatching.

text: Bitterlings have a remarkable reproduction strategy where parents transfer responsibility for the care of their young to mussels. The female extends her ovipositor into the mantle cavity of the mussel and deposits her eggs between the gill filaments. The male then ejects his sperm into the mussel's inhalant water current and fertilization takes place within the gills of the host. The same female may use a number of mussels, and she deposits only one or two yellow, oval eggs into each. Early developmental stages are protected from predation within the body of the mussel. After 3 to 4 weeks larvae swim away from the host to continue life on their own.

text: Guarders[edit]

text:
Guarders: Substrate spawners[34]

Rock tenders
Plant tenders
Terrestrial tenders
Pelagic tenders

Damselfish are substrate spawners. This one keeps her spawn in a gastropod shell

text:
Guarders: Nest spawners[34]

Rock and gravel nesters
Sand nesters
Plant-material nesters

Gluemakers
Nongluemakers

Bubble nesters
Hole nesters
Misc-materials nesters
Anemone nesters

The stickleback glues plant material to make its nest

text: Guarders protect their eggs and offspring after spawning by practicing parental care (also called brood care). Parental care is an "investment by parents in offspring that increases the offsprings' chances of surviving (and hence reproducing). In fish, parental care can take a variety of forms including guarding, nest building, fanning, splashing, removal of dead eggs, retrieval of straying fry, external egg carrying, egg burying, moving eggs or young, ectodermal feeding, oral brooding, internal gestation, brood-pouch egg carrying, etc."[37]

text: Territorial behaviour is generally necessary for guarders, and the embryos are almost always guarded by males (apart from cichlids). There is a need to be territorial because looking after embryos usually includes defending the site where they are being looked after. It also often means there is competition for the best egg-laying sites. Elaborate courtship behaviour is usual among guarders.[4]:145

text: Guarding males keep the embryos safe from predators, keep oxygen levels high by fanning water currents, and keep the area free from dead embryos and debris. They protect the embryos until they hatch, and often look after the larval stages as well. The time spent guarding can range from a few days to several months.[4]:145

text: Substrate spawners[edit]

text: Some guarders build nests (nest spawners) and some do not (substrate spawners), though the difference between the two groups can be small.[4]:142 Substrate spawners clean off a suitable area of surface suitable for egg laying, and look after the area, but they do not actively build a nest.

text:
Baby paradise fish just hatched, gathered under the surface of a bubble nest

Anemone fish nest in an anemone. Here a male is protecting spawn produced by his partner.

text: Bearers[edit]

text:
Bearers: External[34]

Transfer brooders
Auxiliary brooders
Mouth brooders
Gill-chamber brooders
Pouch brooders

Male seahorsees are pouch brooders

A female cichlid mouthbrooding fry which can be seen looking out her mouth

External video

 Mouthbrooding tilapia — YouTube

 Mouthbrooding cichlid — YouTube

text: Bearers are fish that carry their embryos (and sometimes their young) around with them, either externally or internally.

text: External bearers[edit]

text: Mouth brooders - carry eggs or larvae in their mouth. Mouth brooders can be ovophiles or larvophiles. Ovophile or egg-loving mouth-brooders lay their eggs in a pit, which are sucked up into the mouth of the female. The small number of large eggs hatch in the mother's mouth, and the fry remain there for a period of time. Fertilization often occurs with the help of egg-spots, which are colorful spots on the anal fin of the male. When the female sees these spots, she tries to pick up the egg-spots, but instead gets a mouthful of sperm, fertilizing the eggs in her mouth. Many cichlids and some labyrinth fish are ovophile mouthbrooders. Larvophile or larvae-loving mouth-brooders lay their eggs on a substrate and guard them until the eggs hatch. After hatching, the female picks up the fry and keeps them in her mouth. When the fry can fend for themselves, they are released. Some eartheaters are larvophile mouthbrooders.

text: Internal bearers[edit]

text: Facultative internal bearers[edit]

text: The beginning of the evolutionary process of livebearing starts with facultative (optional) internal bearing. The process occurs in several species of oviparous (egg-laying) killifishes which spawn in the normal way on the substrate, but in the process accidentally fertilize eggs which the female retains and does not spawn. These eggs are spawned later, usually without allowing much time for embryonic development.[4]:147

text:
Bearers: Internal[34]

Facultative internal bearers
Obligate internal bearers
Livebearers

Guppies are livebearers. This one has been pregnant for about 26 days.

text: Obligate internal bearers[edit]

text: The next step in the evolution of livebearing is obligate (by necessity) internal bearing, where the female retains all the embryos. "The only source of nutrition for these embryos, however, is the egg yolk, as in externally spawned eggs. This situation, also referred to as ovoviviparity, is characteristic of marine rock fishes and the Lake Baikal sculpins. This strategy allows these fish to have fecundities approaching those of pelagic fish with external fertilization, but it also enables them to protect the young during their most vulnerable stage of development. By contrast, sharks and rays using this strategy produce a relatively small number of embryos and retain them for a few weeks to 16 months or longer. The shorter times spans are characteristic of species that eventually deposit their embryos in the environment, surrounded by a horny capsule; whereas the longer periods are characteristic of sharks that retain the embryos until they are ready to emerge as actively swimming young."[4]:147[38]

text: Viviparous fish[edit]

text: However, some fish do not fit these categories. The livebearing largespring gambusia (Gambusia geiseri) was thought to be ovoviviparous until it was shown in 2001 that the embryos received nutrients from the mother.[39]

text: Spawning grounds[edit]

text: Spawning grounds are the areas of water where aquatic animals spawn, or produce their eggs. After spawning, the spawn may or may not drift to new grounds which become their nursery grounds. Many species undertake migrations each year, and sometimes great migrations, to reach their spawning grounds. For example, lakes and river watersheds can be major spawning grounds for anadromous fish such as salmon. These days, it is often necessary to construct fish ladders and other bypass systems so salmon can navigate their way past hydroelectric dams or other obstructions such as weirs on their way to spawning grounds.[40][41] Coastal fish often use mangroves and estuaries as spawning grounds, while reef fish can find adjacent seagrass meadows that make good spawning grounds. Short-finned eels can travel anything up to three or four thousand kilometres to their spawning ground in deep water somewhere in the Coral Sea.

text: Forage fish often make great migrations between their spawning, feeding and nursery grounds. Schools of a particular stock usually travel in a triangle between these grounds. For example, one stock of herrings have their spawning ground in southern Norway, their feeding ground in Iceland, and their nursery ground in northern Norway. Wide triangular journeys such as these may be important because forage fish, when feeding, cannot distinguish their own offspring.[42]

text: Capelin are a forage fish of the smelt family found in the Atlantic and Arctic oceans. In summer, they graze on dense swarms of plankton at the edge of the ice shelf. Larger capelin also eat krill and other crustaceans. The capelin move inshore in large schools to spawn and migrate in spring and summer to feed in plankton rich areas between Iceland, Greenland, and Jan Mayen. The migration is affected by ocean currents. Around Iceland maturing capelin make large northward feeding migrations in spring and summer. The return migration takes place in September to November. The spawning migration starts north of Iceland in December or January.[43]

text: The diagram on the right shows the main spawning grounds and larval drift routes. Capelin on the way to feeding grounds is coloured green, capelin on the way back is blue, and the breeding grounds are red.[43] In a paper published in 2009, researchers from Iceland recount their application of an interacting particle model to the capelin stock around Iceland, successfully predicting the spawning migration route for 2008.[44]

text: Referred to as "the greatest shoal on earth", the sardine run occurs when millions of sardines migrate from their spawning grounds south of the southern tip of Africa northward along the Eastern Cape coastline. Chinook salmon make the longest freshwater migration of any salmon, over 3,000 kilometres (1,900 mi) up the Yukon River to spawning grounds upstream of Whitehorse, Yukon. Some green sea turtles swim more than 2,600 kilometres (1,600 mi) to reach their spawning grounds.

text: Examples[edit]

text: Fish[edit]

text: Goldfish[edit]

text: Goldfish, like all cyprinids, are egg-layers. They usually start breeding after a significant temperature change, often in spring. Males chase females, prompting them to release their eggs by bumping and nudging them. As the female goldfish spawns her eggs, the male goldfish stays close behind fertilizing them. Their eggs are adhesive and attach to aquatic vegetation. The eggs hatch within 48 to 72 hours. Within a week or so, the fry begins to assume its final shape, although a year may pass before they develop a mature goldfish colour; until then they are a metallic brown like their wild ancestors. In their first weeks of life, the fry grow quickly—an adaptation born of the high risk of getting devoured by the adult goldfish.

text: Carp[edit]

text: A member of the Cyprinidae family, carp spawn in times between April and August, largely dependent upon the climate and conditions they live in. Oxygen levels of the water, availability of food, size of each fish, age, number of times the fish has spawned before and water temperature are all factors known to effect when and how many eggs each carp will spawn at any one time.[45]

text: Siamese fighting fish[edit]

text: Prior to spawning, male Siamese fighting fish build bubble nests of varying sizes at the surface of the water. When a male becomes interested in a female, he will flare his gills, twist his body, and spread his fins. The female darkens in colour and curves her body back and forth. The act of spawning takes place in a "nuptial embrace" where the male wraps his body around the female, each embrace resulting in the release of 10-40 eggs until the female is exhausted of eggs. The male, from his side, releases milt into the water and fertilization takes place externally. During and after spawning, the male uses his mouth to retrieve sinking eggs and deposit them in the bubble nest (during mating the female sometimes assists her partner, but more often she will simply devour all the eggs that she manages to catch). Once the female has released all of her eggs, she is chased away from the male's territory, as it is likely that she'll eat the eggs due to hunger.[46] The eggs then remain in the male's care. He keeps them in the bubble nest, making sure none fall to the bottom and repairing the nest as needed. Incubation lasts for 24–36 hours, and the newly hatched larvae remain in the nest for the next 2–3 days, until their yolk sacs are fully absorbed. Afterwards the fry leave the nest and the free-swimming stage begins.[47]

text:
Siamese fighting fish build bubble nests of varying sizes.

A pair of Siamese fighting fish spawning under their bubble nest.

One-day-old Siamese fighting fish larvae in a bubble nest - their yolk sacs have not yet been absorbed

A 15-day-old free-swimming fry of a Siamese fighting fish

text: Crustaceans[edit]

text:
External video

 Lobster migration train
(from The Trials of Life)

text: Copepods[edit]

text: Copepods are tiny crustaceans which usually reproduce either by broadcast spawning or by sac spawning. Broadcasting copepods scatter their eggs into the water, but sac spawners lay their eggs into an ovigerous sac. Sac spawners spawn few but relatively large eggs that develop slowly. By contrast, broadcast spawners spawn numerous small eggs that develop rapidly.[48] However, the shorter hatch times that result from broadcasting are not short enough to compensate for the higher mortality compared to sac spawners. To produce a given number of hatched eggs, broadcasters must spawn more eggs than sac spawners.[49]

text: Spiny lobsters[edit]

text: After mating, the fertilized eggs of the California spiny lobster are carried on the female's pleopods until they hatch, with between 120,000 and 680,000 carried by a single female.[50] The eggs begin coral red, but darken as they develop to a deep maroon.[51] When she is carrying the eggs, the female is said to be "berried". The eggs are ready to hatch after 10 weeks,[50] and spawning takes place from May to August.[52] The larvae that hatch (called phyllosoma larvae) do not resemble the adults. Instead, they are flat, transparent animals around 14 mm (0.55 in) long, but as thin as a sheet of paper.[53] The larvae feed on plankton,[51] and grow through ten molts into ten further larval stages, the last of which is around 30–32 mm (1.2–1.3 in) long.[53] The full series of larval molts takes around 7 months, and when the last stage molts, it metamorphoses into the puerulus state, which is a juvenile form of the adult, though still transparent.[53] The puerulus larvae settle to the sea floor when the water is near its maximum temperature, which in Baja California is in the fall.[54]

text: Egg-bearing female lobsters migrate inshore from deeper waters to hatch their eggs, though they do not have specific spawning grounds.[55][56] These lobster migrations can occur in close single-file formation "lobster trains".

text: Molluscs[edit]

text: Pacific oysters[edit]

text: Oysters are broadcast spawners, that is, eggs and sperm are released into open water where fertilisation occurs. They are protandric; during their first year they spawn as males by releasing sperm into the water. As they grow over the next two or three years and develop greater energy reserves, they spawn as females by releasing eggs. Bay oysters usually spawn by the end of June. An increase in water temperature prompts a few oysters to spawn. This triggers spawning in the rest, clouding the water with millions of eggs and sperm. A single female oyster can produce up to 100 million eggs annually. The eggs become fertilized in the water and develop rapidly into planktonic larvae. which eventually find suitable sites, such as another oyster's shell, on which to settle. Attached oyster larvae are called spat. Spat are oysters less than 25 millimetres (0.98 in) long.

text: The Pacific oyster usually has separate sexes. Their sex can be determined by examining the gonads, and it can change from year to year, normally during the winter months. In certain environmental conditions, one sex is favoured over the other. Protandry is favoured in areas of high food abundance and protogyny occurs in areas of low food abundance. In habitats with a high food supply, the sex ratio in the adult population tends to favour females, and areas with low food abundances tend to have a larger proportion of male adults. Spawning in the Pacific oyster occurs at 20 °C (68 °F). This species is very fecund, with females releasing about 50–200 million eggs in regular intervals (at a rate of 5–10 times a minute) in a single spawning. Once released from the gonads, the eggs move through the suprabranchial chambers (gills), are then pushed through the gill ostia into the mantle chamber, and are finally released in the water, forming a small cloud. In males, the sperm is released at the opposite end of the oyster, along with the normal exhalent stream of water.[57] A rise in water temperature is thought to be the main cue in the initiation of spawning, as the onset of higher water temperatures in the summer results in earlier spawning in the Pacific oyster.[58]

text: The larvae of the Pacific oyster are planktotrophic, and are about 70 µm at the prodissoconch 1 stage. The larvae move through the water column via the use of a larval foot to find suitable settlement locations. They can spend several weeks at this phase, which is dependent on water temperature, salinity and food supply. Over these weeks, larvae can disperse great distances by water currents before they metamorphose and settle as small spat. Similar to other oyster species, once the Pacific oyster larvae find a suitable habitat, they attach to it permanently using cement secreted from a gland in their foot. After settlement, the larvae metamorphose into juvenile spat. The growth rate is very rapid in optimum environmental conditions, and market size can be achieved in 18 to 30 months.[59]

text:
External video

 Squid spawning

text: Cephalopods[edit]

text: Cephalopods, such as squid and octopuses, have prominent heads and a set of arms (tentacles) modified from the primitive foot of molluscs. All cephalopods are sexually dimorphic. However, they lack external sexual characteristics, so they use colour communication. A courting male approaches a likely looking mate flashing his brightest colours, often in rippling displays. If the other cephalopod is female and receptive, her skin will change colour to become pale, and mating will occur. If the other cephalopod remains brightly coloured, it is taken as a warning.[60]

text: All cephalopods reproduce by spawning eggs. Most cephalopods use semi-internal fertilization where the male places his gametes inside the female's mantle cavity to fertilize the ova in the female's single ovary.[61] The "penis" in most male cephalopods is a long and muscular end of the gonoduct used to transfer spermatophores to a modified sperm-carrying arm called a hectocotylus. That in turn is used to transfer the spermatophores to the female. In species where the hectocotylus is missing, the "penis" is long and able to extend beyond the mantle cavity and transfers the spermatophores directly to the female. In many cephalopods, mating occurs head to head and the male may simply transfer sperm to the female. Others may detach the sperm-carrying arm and leave it attached to the female. Deep water squid have the greatest known penis length relative to body size of all mobile animals, second in the entire animal kingdom only to certain sessile barnacles. Penis elongation in the greater hooked squid may result in a penis that is as long as the mantle, head and arms combined.[62][63]

text: Some species brood their fertilized eggs: female paper nautilus construct shelters for the young, while Gonatiid squid carry a larva-laden membrane from the hooks on their arms.[64] Other cephalopods deposit their young under rocks and aerate them with their tentacles hatching. Mostly the eggs are left to their own devices; many squid lay sausage-like bunches of eggs in crevices or occasionally on the sea floor. Cuttlefish lay eggs separately in cases and attach them to coral or algal fronds.[65] Like Pacific salmon, cephalopods are mostly semelparous, spawning many small eggs in one batch and then dying. Cephalopods usually live fast and die young. Most of the energy extracted from their food is used for growing, and they mature rapidly to their adult size. Some gain as much as 12% of their body mass each day. Most live for one to two years, reproducing and then dying shortly thereafter.[66][67]

text: Echinoderms[edit]

text:
External video

 Sea urchin spawning

text: Echinoderms are marine animals, widespread in all oceans, but not found in fresh water. Just below their skin is an endoskeleton composed of calcareous plates or ossicles.

text: Sea urchins[edit]

text: Sea urchins are spiky echinoderms with spherical bodies which usually contain five gonads. They move slowly, feed mostly on seaweed, and are important for the diet of sea otters. Sea urchins are dioecious, having separate male and female sexes, although there is generally no easy way to distinguish the two. The gonads are lined with muscles underneath the peritoneum, and these allow the animal to squeeze its gametes through the duct and into the surrounding sea water, where fertilization takes place.[68] Their roe (male and female gonads) is soft and melting, with a colour ranging from orange to pale yellow, and is sought after as a human delicacy in many parts of the world.

text: Sea cucumbers[edit]

text: Sea cucumbers are leathery echinoderms with elongated bodies which contain a single, branched gonad. They are found on the sea floor worldwide, and occur in great numbers on the deep sea floor where they often make up the majority of the animal biomass.[69] They feed on plankton and decaying organic debris found at the sea bottom, catching food that flows by with their open tentacles or sifting through bottom sediments. Like sea urchins, most sea cucumbers reproduce by releasing sperm and ova into the ocean water. Depending on conditions, one organism can produce thousands of gametes.

text: Sea cucumbers are typically dioecious, with separate male and female individuals. The reproductive system consists of a single gonad, consisting of a cluster of tubules emptying into a single duct that opens on the upper surface of the animal, close to the tentacles.[68] Many species fertilise their eggs internally. The fertilised egg develops in a pouch on the adult's body and eventually hatches as a juvenile sea cucumber.[70] A few species brood their young inside the body cavity, giving birth through a small rupture in the body wall close to the anus. The remaining species develop their eggs into a free-swimming larva, usually after about three days of development. This larva swims by means of a long band of cilia wrapped around its body. As the larva grows it transforms into a barrel-shaped body with three to five separate rings of cilia. The tentacles are usually the first adult features to appear, before the regular tube feet.[68]

text: Amphibious animals[edit]

text:
Amphibians have successfully solved most of the problems associated with exposure to air. But their reproductive system was and is linked to water, and it remains very fishlike. Almost all amphibians spawn in water and lay a great number of small eggs that hatch quickly into swimming larvae. The eggs do not need any complex protection against drying, because if the environment dries, the larvae are doomed as well as the eggs. Thus selection has acted to encourage the selection of suitable sites for laying eggs, rather than suitable devices for protecting eggs. Both fishes and amphibians may migrate long distances for spawning, and favoured sites are often disputed vigorously.

Richard Cowen[71]:117–8

text: Amphibians are found in and around fresh water lakes and ponds, but not in marine environments. Examples are frogs and toads, salamanders, newts and caecilians (which resemble snakes). They are cold-blooded animals that metamorphose from a juvenile water-breathing form, usually to an adult air-breathing form, though mudpuppies retain juvenile gills in adulthood.

text: Frogs and toads[edit]

text: Female frogs and toads usually spawn gelatinous egg masses containing thousands of eggs in water. Different species lay eggs in distinctive and identifiable ways. For example, the American toad lays long strings of eggs. The eggs are highly vulnerable to predation, so frogs have evolved many techniques to ensure the survival of the next generation. In colder areas the embryo is black to absorb more heat from the sun, which speeds up development. Most commonly, this involves synchronous reproduction. Many individuals will breed at the same time, overwhelming the actions of predators; the majority of the offspring will still die due to predation, but there is a greater chance some will survive. Another way in which some species avoid predators and the pathogens eggs are exposed to in ponds is to lay eggs on leaves above the pond, with a gelatinous coating designed to retain moisture. In these species the tadpoles drop into the water upon hatching. The eggs of some species laid out of water can detect vibrations of nearby predatory wasps or snakes, and will hatch early to avoid being eaten.[72]

text: While the length of the egg stage depends on the species and environmental conditions, aquatic eggs generally hatch within one week. Unlike salamanders and newts, frogs and toads never become sexually mature while still in their larval stage. The hatched eggs continue life as tadpoles, which typically have oval bodies and long, vertically flattened tails. As a general rule, free living larvae are fully aquatic. They lack eyelids and have a cartilaginous skeleton, a lateral line system, gills for respiration (external gills at first, internal gills later) and tails with dorsal and ventral folds of skin for swimming.[73] They quickly develop a gill pouch that covers the gills and the front legs; the lungs are also developed at an early stage as an accessory breathing organ. Some species which go through the metamorphosis inside the egg and hatch to small frogs never develop gills; instead there are specialised areas of skin that take care of respiration. Tadpoles also lack true teeth, but the jaws in most species usually have two elongate, parallel rows of small keratinized structures called keradonts in the upper jaw while the lower jaw has three rows of keradonts, surrounded by a horny beak, but the number of rows can be lower (sometimes zero), or much higher.[74] Tadpoles feed on algae, including diatoms filtered from the water through the gills. Some species are carnivorous at the tadpole stage, eating insects, smaller tadpoles, and fish. Cannibalism has been observed among tadpoles. Early developers who gain legs may be eaten by the others, so the late bloomers survive longer.[75]

text: Sea turtles[edit]

text:
External video

 Spawning sea turtle

text: Sea turtles are amphibious reptiles, but they are not amphibians. Reptiles belong to the class Reptilia while amphibians belong to the class Amphibia. These are two distinct taxonomic groups. Reptiles have scales and leathery skins, while the skins of amphibians are smooth and porous. Unlike frogs, sea turtle eggs have tough, leathery shells which allow them to survive on land without drying out.

text: Some sea turtles migrate long distances between feeding and spawning grounds. Green turtles have feeding grounds along the Brazilian coast. Each year, thousands of these turtles migrate about 2,300 kilometres (1,400 mi) to their spawning ground, Ascension Island in the Atlantic, an island only 11 kilometres (6.8 mi) across. Each year the returning turtles dig between 6,000 and 15,000 nests, often returning to the same beach from where they hatched. Females usually mate every two to four years. Males on the other hand visit the breeding areas every year, attempting to mate.[76] Green sea turtles' mating is similar to other marine turtles. Female turtles control the process. A few populations practice polyandry, although this does not seem to benefit hatchlings.[77] After mating in the water, the female moves above the beach's high tide line where she digs a hole with her hind flippers and deposits her eggs. Litter size depends on the age of the female and species, but green turtle clutches range between 100 and 200. She then covers the nest with sand and returns to the sea.[78]

text: At around 45 to 75 days, the eggs hatch during the night and the hatchlings instinctively head directly into the water. This is the most dangerous time in a turtle's life. As they walk, predators such as gulls and crabs grab them. A significant percentage never make it to the ocean. Little is known of the initial life history of newly hatched sea turtles.[79] Juveniles spend three to five years in the open ocean before they settle as still-immature juveniles into their permanent shallow-water lifestyle.[80][81] It is speculated that they take twenty to fifty years to reach sexual maturity. Individuals live up to eighty years in the wild.[78] They are among the larger sea turtles, many more than a meter long and weighing up to 300 kilograms (660 lb).[82]

text: Aquatic insects[edit]

text: Aquatic insects also spawn. Mayflies "are famed for their short adult life. Some species have under an hour to mate and lay their eggs before they die. Their pre-adult stage, known as the subimago, may be even shorter - perhaps lasting just a few minutes before they moult into their adult form. Therefore a mayfly spends most of its life as a nymph, hidden from view under the water."[83]

text: Corals[edit]

text: Corals can be both gonochoristic (unisexual) and hermaphroditic, each of which can reproduce sexually and asexually. Reproduction also allows corals to settle new areas.

text: Corals predominantly reproduce sexually. 25% of hermatypic corals (stony corals) form single sex (gonochoristic) colonies, while the rest are hermaphroditic.[36] About 75% of all hermatypic corals "broadcast spawn" by releasing gametes—eggs and sperm—into the water to spread offspring. The gametes fuse during fertilization to form a microscopic larva called a planula, typically pink and elliptical in shape. A typical coral colony form several thousand larvae per year to overcome the odds against formation of a new colony.[84]

text: Planulae exhibit positive phototaxis, swimming towards light to reach surface waters where they drift and grow before descending to seek a hard surface to which they can attach and establish a new colony. They also exhibit positive sonotaxis, moving towards sounds that emanate from the reef and away from open water.[85] High failure rates afflict many stages of this process, and even though millions of gametes are released by each colony very few new colonies form. The time from spawning to settling is usually 2–3 days, but can be up to 2 months.[86] The larva grows into a polyp and eventually becomes a coral head by asexual budding and growth.

text: Synchronous spawning is very typical on the coral reef and often, even when multiple species are present, all corals spawn on the same night. This synchrony is essential so that male and female gametes can meet. Corals must rely on environmental cues, varying from species to species, to determine the proper time to release gametes into the water. The cues involve lunar changes, sunset time, and possibly chemical signalling.[36] Synchronous spawning may form hybrids and is perhaps involved in coral speciation.[87] In some places the spawn can be visually dramatic, clouding the usually clear water with gametes, typically at night.

text: Corals use two methods for sexual reproduction, which differ in whether the female gametes are released:

text:
Broadcasters, the majority of which mass spawn, rely heavily on environmental cues, because they release both sperm and eggs into the water. The corals use long-term cues such as day length, water temperature, and/or rate of temperature change. The short-term cue is most often the lunar cycle, with sunset cuing the release.[36] About 75% of coral species are broadcasters, the majority of which are hermatypic, or reef-building corals.[36] The positively buoyant gametes float towards the surface where fertilization produces planula larvae. The larvae swim towards the surface light to enter into currents, where they usually remain for two days, but sometimes up to three weeks, and in one known case two months,[86] after which they settle and metamorphose into polyps and form colonies.
Brooders are most often ahermatypic (non-reef building) in areas of high current or wave action. Brooders release only sperm, which is negatively buoyant, and can harbor unfertilized eggs for weeks, lowering the need for mass synchronous spawning events, which do sometimes occur.[36] After fertilization the corals release planula larvae which are ready to settle.[88]

text: Fungi[edit]

text: Fungi are not plants, and require different conditions for optimal growth. Plants develop through photosynthesis, a process that converts atmospheric carbon dioxide into carbohydrates, especially cellulose. While sunlight provides an energy source for plants, mushrooms derive all of their energy and growth materials from their growth medium, through biochemical decomposition processes. This does not mean that light is an unnecessary requirement, since some fungi use light as a signal to induce fruiting. However, all the materials for growth must already be present in the growth medium. Instead of seeds, mushrooms reproduce sexually during underground growth, and asexually through spores. Either of these can be contaminated with airborne microorganisms, which will interfere with mushroom growth and prevent a healthy crop. Mycelium, or actively growing mushroom culture, is placed on growth substrate to seed or introduce mushrooms to grow on a substrate. This is also known as inoculation, spawning or adding spawn. Its main advantages are to reduce chances of contamination while giving mushrooms a firm beginning.[89][90]

text: Gallery[edit]

text:
Spawning brittle star

Head of female krill with her brood sac

Spawning sockeye salmon

Dead salmon after spawning

These lagoons, connected to the River Tees, provide a quiet backwater for fish to spawn and to take refuge in times of high water levels

In the middle of this weir is a fish ladder, which allows trout and salmon to pass the weir to go upriver to spawn.


document_title: Escape the Night

question_text: how did roi die in escape the night

question_tokens: how did roi die in escape the night

root

text: Escape the Night

text: Premise

text: The series follows The Savant (Joey Graceffa) as he finds himself in an estate in a past era, where he invites a number of guests to a party which requires them to act and dress as various personas from that era. Once there, they’re cut off from the outside world, challenged to survive the night and escape the estate. To do this, the guests team up with him to participate in challenges and escape room puzzles, competing with each other to escape from the historical era by solving and completing them. At the end of each episode, two guests are voted into a challenge to compete against each other, where the losing guest is eliminated via a fictional death until one or more guests ultimately win and are sent back to the modern world.

tag: p

text: Cast and characters

text: Season 1 (1920s)

text: Guests

text:
Name
Role
Eliminated

MyLifeAsEva
The Journalist
Escaped

Oli White
The Big Game Hunter

Lele Pons
The Hustler
Episode 9

Timothy DeLaGhetto
The Mobster
Episode 8

Nadeshot
The Professor
Episode 7

Sierra Furtado
The Heiress
Episode 6

GloZell Green
The Jazz Singer
Episode 4

iJustine
The Gambler
Episode 3

Andrea Brooks
The Fixer
Episode 2

Shane Dawson
The Renegade
Episode 1

tag: table

text: Recurring

text:
Paul Chirico as Arthur, head of staff.
Katia Hayes as Sarah, the maid.
David Hutchison as Marvin, the groundskeeper.

tag: ul

text: Season 2 (The Victorian Era)

text: Guests

text:
Name
Role
Eliminated

Andrea Russett
The Mystic
Escaped

Tyler Oakley
The Thespian

Alex Wassabi
The Novelist
Episode 9

The Gabbie Show
The Vaudevillian
Episode 7

Tana Mongeau
The Saloon Girl
Episode 6

Liza Koshy
The Explorer
Episode 5

DeStorm Power
The Railroad Tycoon
Episode 4

Jesse Wellens
The Outlaw
Episode 3

LaurDIY
The Engineer
Episode 2

text: Recurring

text:
Lindsay Elston as Alison.
Eva Augustina Sinnotte as the Sorceress.

text: Season 3 (October 13th, 1978)

text: Guests

text:
Name
Role
Eliminated

MatPat
The Detective

Escaped

Nikita Dragun
The Troublemaker

Manny MUA
The Record Producer

Episode 9

Rosanna Pansino
The Jet Setter

Episode 8

Safiya Nygaard
The Investigative Reporter

Episode 7

Colleen Ballinger
The Disco Dancer

Episode 6

Teala Dunn
The Super Spy
Episode 4

Guava Juice
The Daredevil
Episode 3

JC Caylen
The Hippie
Episode 2

text: Recurring

text:
Shontae Saldana as Calliope.
Jack O'Conner as Mortimer.
Micah Fitzgerald as the Carnival Master.

text: Episodes

text: SeasonEpisodesOriginally airedFirst airedLast aired110June 22, 2016 (2016-06-22)August 17, 2016 (2016-08-17)210June 22, 2017 (2017-06-22)August 16, 2017 (2017-08-16)310June 21, 2018 (2018-06-21)August 15, 2018 (2018-08-15)Specials4August 24, 2016 (2016-08-24)August 30, 2017 (2017-08-30)

text: Season 1 (2016)

text:
No.overallNo. inseasonTitleOriginal air date11"An Invitation"June 22, 2016 (2016-06-22)
22"The Ungodly Machine"June 22, 2016 (2016-06-22)
33"Buried Alive"June 29, 2016 (2016-06-29)
44"Mannequins"July 6, 2016 (2016-07-06)
55"Freak Show"July 13, 2016 (2016-07-13)
66"Did Someone Call For An Exorcist?"July 20, 2016 (2016-07-20)
77"Mermaid Tails"July 27, 2016 (2016-07-27)
88"All Out War"August 3, 2016 (2016-08-03)
99"Wicked Hallucinations"August 10, 2016 (2016-08-10)
1010"Betrayal At The House On The Hill"August 17, 2016 (2016-08-17)

text: Season 2 (2017)

text:
No.overallNo. inseasonTitleOriginal air date111"The Masquerade Part 1"June 22, 2017 (2017-06-22)
122"The Masquerade Part 2"June 22, 2017 (2017-06-22)
133"Tangled Web"June 28, 2017 (2017-06-28)
144"A Nation Divided"July 5, 2017 (2017-07-05)
155"The Gingerbread Woman"July 12, 2017 (2017-07-12)
166"Endless Winter Night"July 19, 2017 (2017-07-19)
177"Automaton Love Story"July 26, 2017 (2017-07-26)
188"Full Moon Slaughter"August 2, 2017 (2017-08-02)
199"The Dark Dimension"August 9, 2017 (2017-08-09)
2010"The Sorceress"August 16, 2017 (2017-08-16)

text: Season 3 (2018)

text:
No.overallNo. inseasonTitleOriginal air date211"The Clowns Here Kill Part 1"June 21, 2018 (2018-06-21)
222"The Clowns Here Kill Part 2"June 21, 2018 (2018-06-21)
233"Venomous Affections"June 27, 2018 (2018-06-27)
244"The Man With No Name"July 4, 2018 (2018-07-04)
255"Strong Like A Demon"July 11, 2018 (2018-07-11)
266"Twin Dolls"July 18, 2018 (2018-07-18)
277"Funhouse"July 25, 2018 (2018-07-25)
288"Wicked Witches"August 1, 2018 (2018-08-01)
299"Control Issues"August 8, 2018 (2018-08-08)
3010"TBA"August 15, 2018 (2018-08-15)

text: Specials (2016-17)

text:
No.TitleOriginal air date1"How to Kill a YouTuber"August 24, 2016 (2016-08-24)
2"BTS Documentary: The Making of 'Escape the Night'"August 24, 2016 (2016-08-24)
3"Monster's Ball"August 23, 2017 (2017-08-23)
4"Behind the Scenes with Joey Graceffa"August 30, 2017 (2017-08-30)

text: Production

text: Development

text: In October 2015, YouTube announced YouTube Red, a paid subscription service that would allow streaming videos ad-free, downloading videos for offline usage, and present new exclusive original series for YouTube Red subscribers.[4][5] At the time of announcement, ten various series were announced for 2016, including the Untitled Joey Graceffa project,[6][7] which was set to be produced by Brian Graden Media.[3] The series began filming near Valencia, California.[8]

text: On June 15, 2016, Graceffa released the trailer for his original series entitled Escape the Night,[9] which was set and released on June 22, 2016 with two episodes going live.[10] When interviewed after production, Graceffa commented that the idea behind Escape the Night was inspired by an episode themed around murder mystery appearing on television show Lizzie McGuire,[11] and closely related to the 1985 film Clue.[8] Furthermore, Graceffa shared his experience with filming the series, expressing "It was a really fun concept to put together," additionally mentioning, "And it was an idea that started small and ended up into something much bigger."[3]

text: On October 17, 2016, it was announced by Susanne Daniels, global head of content for YouTube, at MIPCOM that Escape the Night would be renewed for a second season.[12] Later on October 31, 2016, Joey Graceffa via Twitter announced the cast of the second season and scheduled its debut to be on June 22, 2017.[13][14]

text: On May 24, 2018, Joey Graceffa announced the third season via Twitter.[15] On May 28, 2018 through June 1, 2018, Joey Graceffa confirmed via Twitter[16] he would be releasing the cast of season three periodically. The third season debuted on June 21, 2018.

text: Reception

text: Common Sense Media's critical consensus reads, "Web celebs star in mediocre pseudo-reality horror series", while giving the show a rating of 2/5.[17]

text: Game charts

text: Progress chart (season 1)

text:
Progress Chart

Guest

1
2
3
4
5
6
7
8
9
10
Cause of Death

Joey

Safe

Safe

Safe

Safe

Safe

Safe

Safe

Safe

Safe

Safe

Escaped

Eva

Safe

Safe

Safe

Safe

Safe

Safe

Safe

Safe

Safe

Safe

Oli

Safe

Safe

Safe

Safe

Safe

Safe

Safe

Safe

Safe

Safe

Lele

Safe

Safe

Safe

Safe

Safe

Safe

Safe

Safe

Dead

Electrocuted

Timothy

Safe

Safe

Safe

Safe

Safe

Safe

Safe

Dead

Gunshot to the head

Matthew

Safe

Safe

Safe

Safe

Safe

Safe

Dead

Poisoned

Sierra

Safe

Safe

Safe

Safe

Safe

Dead

Killed during an exorcism

GloZell

Safe

Safe

Safe

Dead²

Choked on blood

Justine

Safe

Safe

Dead

Buried alive

Andrea

Safe

Dead

Asphyxiated by poison gas

Shane

Dead¹

Poisoned

text:
¹ Shane knew about the evil of the house and informed Sarah the maid that he knew what she was doing. As a result, the evil saw Shane as a threat and poisoned him. In order to save him, the other guests had to complete a puzzle task within a time limit. They failed, resulting in his death.
² Joey and Lele were voted into a challenge, and they had to choose a guest to die. They chose to betray GloZell.

text: Progress chart (season 2)

text:
Progress Chart

Guest
1
2
3
4
5
6
7
8
9
10
Cause of Death

Andrea

Safe

Safe

Safe

Safe

Safe

Safe

Safe

Safe²

Safe

Escaped

Survived

Tyler

Safe

Safe

Safe

Safe

Safe

Safe

Safe

Safe

Safe

Joey

Safe

Safe

Safe

Safe

Safe

Safe

Safe

Safe

Safe

Dead

Stabbed by Sorceress, later resurrected

Alex

Safe

Safe

Safe

Safe

Safe

Safe

Safe

Safe

Dead

Stabbed in the chest

Gabbie

Safe

Safe

Safe

Safe

Safe

Safe

Dead

Heart ripped out

Tana

Safe

Safe

Safe

Safe

Safe

Dead¹

Stomach slashed

Liza

Safe

Safe

Safe

Safe

Dead

Throat slit

DeStorm

Safe

Safe

Safe

Dead

Shot with a glowing arrow

Jesse

Safe

Safe

Dead

Eaten by Jorogumo

Lauren

Safe

Dead

Eaten by vampires

text:
¹ Joey and Andrea were voted into a challenge, and they had to choose a guest to die. They chose to betray Tana.
² Everyone had to compete in this challenge, with whoever finished last being the one to die. Andrea ended up finishing last, but Alison (their assistant) sacrificed herself so that she could live.

text: Progress chart (season 3)

text:
Guest
1
2
3
4
5
6
7
8
9
10
Cause of Death

Joey

Safe1

Safe

Safe

Safe

Safe

Safe

Safe

Safe

Safe

TBA

TBA

Matthew

Safe

Safe

Safe

Safe

Dead

Safe2

Safe

Safe

TBA

TBA

Nikita

Safe

Safe

Safe

Safe

Safe

Safe

Safe

Safe

Safe

TBA

TBA

Manny

Safe

Safe

Safe

Safe

Safe

Safe

Safe

Safe

Dead

Shot to death by Nikita

Rosanna

Safe

Safe

Safe

Safe

Safe

Safe

Safe

Dead

Stabbed in a ritual sacrifice

Safiya

Safe

Safe

Safe

Safe

Safe

Safe

Dead3

Fishhooked

Colleen

Safe

Safe

Safe

Safe

Safe

Dead

Impaled by the Iron Maiden

Teala

Safe

Safe

Safe

Dead

Strangled

Roi

Safe

Safe

Dead

Bitten by the Snake Woman

JC

Safe

Dead

Stabbed in the gut

text:
1 Joey is resurrected temporarily, and in order to save his life, his friends must die
2 Matthew was beaten to death in Episode 5, but was revived by the Harp of Lazarus in Episode 7.
3 Safiya and Rosanna had to vote two into the challenge. Safiya voted for Nikita, while Rosanna voted for Manny. In a shocking turn of events, the person that voted for the winner of the challenge ended up being killed. Nikita won, and Safiya was fishhooked.


document_title: Blue Bloods (season 8)

question_text: who is playing the new mayor on blue bloods

text: Blue Bloods (season 8)

text: Cast[edit]

text: Donnie Wahlberg (Danny Reagan), Bridget Moynahan (Erin Reagan), Will Estes (Jamie Reagan), and Len Cariou (Henry Reagan) are first credited. Then Sami Gayle (Nicky Reagan-Boyle) is credited next, marking the fourth season she has been included in the opening credits. Tom Selleck (Frank Reagan) receives an "and" billing at the close of the main title sequence. Amy Carlson (Linda Reagan) left between Seasons 7 and 8.

text: Marisa Ramirez, as Danny's partner Detective Maria Baez, and Vanessa Ray, as Jamie's partner Eddie Janko, continue to receive "also starring" billing for season 8. Appearing regularly and receiving "special guest star" billing are Gregory Jbara as Deputy Commissioner of Public Information Garrett Moore, Robert Clohessy as Lt. Sidney Gormley, and Abigail Hawk as Detective Abigail Baker, Frank's primary aide.

text: Episodes[edit]

text:
No.
overall
No. in
season
Title
Directed by
Written by
Original air date
Prod.
code
U.S. viewers
(millions)

156
1
"Cutting Losses"
David M. Barrett
Siobhan Byrne O'Connor
September 29, 2017 (2017-09-29)
801
10.04[3]

Erin pleads with Danny, who has been contemplating retirement since Linda's death in a rescue helicopter crash, to help her with a case involving her ex-husband, Jack (Peter Hermann) who's been attacked in his office. Jamie and Eddie go undercover as a couple to bust a shady drug dealer; new mayor Margaret Dutton (Lorraine Bracco) butts heads with Frank.

157
2
"Ghosts of the Past"
John Behring
Kevin Riley
October 6, 2017 (2017-10-06)
803
9.49[4]

Frank receives an order from the mayor to attend the annual West Indies parade, which this year is honoring a man who served time for conspiring in an attack against the police. Meanwhile, Danny and Maria investigate the return of Selena Moore (Caroline Pluta), who suspiciously disappeared as a teen 13 years ago. Also, Jamie and Eddie try to help a young woman they believe is being exploited by Congressman Richard Walters (Richard Thomas).

158
3
"The Enemy of My Enemy"
Robert Harmon
Ian Biederman
October 13, 2017 (2017-10-13)
802
8.98[5]

Erin's case against human trafficker Chao Lin (Tia Carrere) faces difficulty when the presiding judge falls off a roof to his death. Danny and Baez investigate, while also trying to protect a key witness for the prosecution. Elsewhere, Frank's enhanced public safety initiative is opposed by Mayor Dutton, but gains a surprising ally, City Council Speaker Regina Thomas (Whoopi Goldberg).

159
4
"Out of the Blue"
David M. Barrett
Brian Burns
October 20, 2017 (2017-10-20)
804
9.08[6]

Danny and Baez work the case of a detective who was gunned down prior to testifying against a career criminal. Also, Frank personally investigates when Garrett is attacked by a SWAT team outside his home, and Erin brings in a confidential informant against Anthony's wishes.

160
5
"The Forgotten"
Ralph Hemecker
Allie Solomon
October 27, 2017 (2017-10-27)
805
8.29[7]

Danny and Baez investigate the murder of a single mother whose ex-husband has a documented history of violence. Also, Frank deals with the fallout when Mayor Dutton eliminates solitary confinement in prisons, while Jamie's effort to save a young woman who overdosed on heroin has unexpected consequences.

161
6
"Brushed Off"
Eric Laneuville
Daniel Truly
November 3, 2017 (2017-11-03)
806
9.27[8]

When a famous basketball player is found dead of an apparent drug overdose, Danny and Maria look into his possible ties to a local drug gang. Also, Erin revisits the case of a man she may have wrongfully convicted nine years ago, and Frank is approached by Archbishop Kearns (Stacey Keach) regarding an eviction matter Jamie and Eddie are working on.

162
7
"Common Ground"
David M. Barrett
Siobhan Byrne O'Connor
November 10, 2017 (2017-11-10)
807
9.94[9]

A case turns personal for Danny when he works to protect a nurse, Faith Madson (Jessie Mueller), from her violent ex-boyfriend. Meanwhile, Shelly Wayne (Cassandra Freeman), an acquaintance of Frank's, comes to him with a theory regarding the death of an inmate. Also, Jamie and Eddie help deliver a baby, only to learn that the mother and her family are undocumented immigrants living in deplorable conditions.

163
8
"Pick Your Poison"
Heather Cappiello
Kevin Wade
November 17, 2017 (2017-11-17)
808
9.25[10]

Eddie makes a questionable arrest of a man revealed to be a college acquaintance who once humiliated her in a frat house. Frank learns one of his best lieutenants tested positive for marijuana after a trip to Colorado, and gets caught between department regulations and Mayor Dutton's stance on making pot legal. Meanwhile, Danny and Baez investigate a murder linked to a white supremacist group.

164
9
"Pain Killers"
John Behring
Ian Biederman
December 1, 2017 (2017-12-01)
809
8.84[11]

As Danny and Baez join a narcotics task force to track down a drug supplier at a prep school, Baez comes into contact with fentanyl and is soon fighting for her life from an accidental overdose. Also, Jamie and Eddie work to protect a rehabilitated sex offender whose neighbors are angry he lives in their apartment building, and Frank forms an unlikely alliance with Mayor Dutton when the Governor refuses to involve the NYPD during a major state trooper initiative.

165
10
"Heavy Is the Head"
David M. Barrett
Brian Burns
December 8, 2017 (2017-12-08)
810
9.40[12]

Erin is conflicted when Jamie and Eddie ask her to help drop old charges against a man, Parker Mack (Spencer House), who just bravely rescued a woman from a local hostage situation. Meanwhile, Danny and Baez work a case involving car thieves and discover the leader is Victor Lugo (Nick Cordero), a mobster they've dealt with before. Also, Baker receives a job offer which Frank learns may have strings attached.

166
11
"Second Chances"
Deran Sarafian
Kevin Riley
January 5, 2018 (2018-01-05)
811
9.98[13]

When a journalist disappears while working on an exposé about an innocent man serving time for murder, Danny and Baez hope that reexamining the original case will help find her. Also, Frank reluctantly speaks out against an initiative led by Erin's office to consider drug abuse as a disease first, and a crime second.

167
12
"The Brave"
Tom Moore
Siobhan Byrne O'Connor
January 12, 2018 (2018-01-12)
812
10.17[14]

Anthony is shot while interviewing a witness for an upcoming murder trial. Despite their differences, Danny takes up the case to find out who was responsible, telling Erin that Anthony is still "one of us". Also, Jamie and Eddie get in the middle of a standoff between a police lieutenant and a developmentally disabled man posing as an officer, and Nicky prepares to take the police exam over her mom's objections.

168
13
"Erasing History"
Jane Raab
Daniel Truly
January 19, 2018 (2018-01-19)
813
9.45[15]

When Henry is the key witness on Danny and Baez's case, his meddling pushes Danny's buttons until he leads them to valuable information. Also, Nicky shocks her family by siding with her activist friend, Christie (Naian Gonzalez Norvind), who defaced the NYPD flag at One Police Plaza, and Jamie and Eddie learn a parole officer is taking advantage of his power over parolees.

169
14
"School of Hard Knocks"[16]
Alex Zakrzewski
Ian Biederman
February 2, 2018 (2018-02-02)
814
TBD

text: Ratings[edit]

text:
No.
Title
Air date
Rating/share
(18–49)
Viewers
(millions)
DVR
(18–49)
DVR viewers
(millions)
Total
(18–49)
Total viewers
(millions)

1
"Cutting Losses"
September 29, 2017
1.1/5
10.04[3]
0.7
4.57
1.8
14.60[17]

2
"Ghosts of the Past"
October 6, 2017
1.0/4
9.49[4]
0.7
4.18
1.7
13.67[18]

3
"The Enemy of My Enemy"
October 13, 2017
0.9/4
8.98[5]
0.6
4.13
1.5
13.11[19]

4
"Out of the Blue"
October 20, 2017
0.9/4
9.08[6]
0.7
4.12
1.6
13.20[20]

5
"The Forgotten"
October 27, 2017
0.9/4
8.29[7]
N/A
4.14
N/A
12.43[21]

6
"Brushed Off"
November 3, 2017
0.9/4
9.27[8]
N/A
3.97
N/A
13.24[22]

7
"Common Ground"
November 10, 2017
1.0/5
9.94[9]
0.7
3.84
1.7
13.78[23]

8
"Pick Your Poison"
November 17, 2017
0.9/4
9.25[10]
N/A
4.14
N/A
13.40[24]

9
"Pain Killers"
December 1, 2017
0.8/4
8.84[11]
0.7
4.54
1.5
13.41[25]

10
"Heavy is the Head"
December 8, 2017
0.9/4
9.40[12]
0.7
4.07
1.6
13.47[26]

11
"Second Chances"
January 5, 2018
1.0/4
9.98[13]
TBD
TBD
TBD
TBD

12
"The Brave"
January 12, 2018
1.0/4
10.17[14]
TBD
TBD
TBD
TBD

13
"Erasing History"
January 19, 2018
TBD
TBD
TBD
TBD
TBD
TBD

14
"School of Hard Knocks"
February 2, 2018
TBD
TBD
TBD
TBD
TBD
TBD


document_title: Ultraviolet–visible spectroscopy

question_text: if a solution is blue what color will it show the most response in terms of absorption

text: Ultraviolet–visible spectroscopy

text: Principle of ultraviolet-visible absorption[edit]

text: Molecules containing π-electrons or non-bonding electrons (n-electrons) can absorb the energy in the form of ultraviolet or visible light to excite these electrons to higher anti-bonding molecular orbitals.[2] The more easily excited the electrons (i.e. lower energy gap between the HOMO and the LUMO), the longer the wavelength of light it can absorb. There are four possible types of transitions (π-π*, n-π*, σ-σ*, and n-σ*), and they can be ordered as follows: σ-σ* > n-σ* > π-π* > n-π*.[citation needed]

text: Applications[edit]

text: UV/Vis spectroscopy is routinely used in analytical chemistry for the quantitative determination of different analytes, such as transition metal ions, highly conjugated organic compounds, and biological macromolecules. Spectroscopic analysis is commonly carried out in solutions but solids and gases may also be studied.

text:
Solutions of transition metal ions can be colored (i.e., absorb visible light) because d electrons within the metal atoms can be excited from one electronic state to another. The colour of metal ion solutions is strongly affected by the presence of other species, such as certain anions or ligands. For instance, the colour of a dilute solution of copper sulfate is a very light blue; adding ammonia intensifies the colour and changes the wavelength of maximum absorption (λmax).
Organic compounds, especially those with a high degree of conjugation, also absorb light in the UV or visible regions of the electromagnetic spectrum. The solvents for these determinations are often water for water-soluble compounds, or ethanol for organic-soluble compounds. (Organic solvents may have significant UV absorption; not all solvents are suitable for use in UV spectroscopy. Ethanol absorbs very weakly at most wavelengths.) Solvent polarity and pH can affect the absorption spectrum of an organic compound. Tyrosine, for example, increases in absorption maxima and molar extinction coefficient when pH increases from 6 to 13 or when solvent polarity decreases.
While charge transfer complexes also give rise to colours, the colours are often too intense to be used for quantitative measurement.

text: The Beer-Lambert law states that the absorbance of a solution is directly proportional to the concentration of the absorbing species in the solution and the path length.[3] Thus, for a fixed path length, UV/Vis spectroscopy can be used to determine the concentration of the absorber in a solution. It is necessary to know how quickly the absorbance changes with concentration. This can be taken from references (tables of molar extinction coefficients), or more accurately, determined from a calibration curve.

text: A UV/Vis spectrophotometer may be used as a detector for HPLC. The presence of an analyte gives a response assumed to be proportional to the concentration. For accurate results, the instrument's response to the analyte in the unknown should be compared with the response to a standard; this is very similar to the use of calibration curves. The response (e.g., peak height) for a particular concentration is known as the response factor.

text: The wavelengths of absorption peaks can be correlated with the types of bonds in a given molecule and are valuable in determining the functional groups within a molecule. The Woodward-Fieser rules, for instance, are a set of empirical observations used to predict λmax, the wavelength of the most intense UV/Vis absorption, for conjugated organic compounds such as dienes and ketones. The spectrum alone is not, however, a specific test for any given sample. The nature of the solvent, the pH of the solution, temperature, high electrolyte concentrations, and the presence of interfering substances can influence the absorption spectrum. Experimental variations such as the slit width (effective bandwidth) of the spectrophotometer will also alter the spectrum. To apply UV/Vis spectroscopy to analysis, these variables must be controlled or accounted for in order to identify the substances present.[4]

text: The method is most often used in a quantitative way to determine concentrations of an absorbing species in solution, using the Beer-Lambert law:

text:
where A is the measured absorbance (in Absorbance Units (AU)),

I

0

{\displaystyle I_{0}}

 is the intensity of the incident light at a given wavelength,

I

{\displaystyle I}

 is the transmitted intensity, L the path length through the sample, and c the concentration of the absorbing species. For each species and wavelength, ε is a constant known as the molar absorptivity or extinction coefficient. This constant is a fundamental molecular property in a given solvent, at a particular temperature and pressure, and has units of

1

/

M
∗
c
m

{\displaystyle 1/M*cm}

.

text: The absorbance and extinction ε are sometimes defined in terms of the natural logarithm instead of the base-10 logarithm.

text: The Beer-Lambert Law is useful for characterizing many compounds but does not hold as a universal relationship for the concentration and absorption of all substances. A 2nd order polynomial relationship between absorption and concentration is sometimes encountered for very large, complex molecules such as organic dyes (Xylenol Orange or Neutral Red, for example).[citation needed]

text: UV-Vis spectroscopy is also used in the semiconductor industry to measure the thickness and optical properties of thin films on a wafer. UV-Vis spectrometers are used to measure the reflectance of light, and can be analyzed via the Forouhi-Bloomer dispersion equations to determine the Index of Refraction (n) and the Extinction Coefficient (k) of a given film across the measured spectral range.[citation needed]

text: Practical considerations[edit]

text: The Beer-Lambert law has implicit assumptions that must be met experimentally for it to apply; otherwise there is a possibility of deviations from the law.[5] For instance, the chemical makeup and physical environment of the sample can alter its extinction coefficient. The chemical and physical conditions of a test sample therefore must match reference measurements for conclusions to be valid.

text: Spectral bandwidth[edit]

text: It is important to have a monochromatic source of radiation for the light incident on the sample cell.[5] Monochromaticity is measured as the width of the "triangle" formed by the intensity spike, at one half of the peak intensity. A given spectrometer has a spectral bandwidth that characterizes how monochromatic the incident light is.[clarification needed]If this bandwidth is comparable to (or more than) the width of the absorption line, then the measured extinction coefficient will be mistaken. In reference measurements, the instrument bandwidth (bandwidth of the incident light) is kept below the width of the spectral lines. When a test material is being measured, the bandwidth of the incident light should also be sufficiently narrow. Reducing the spectral bandwidth reduces the energy passed to the detector and will, therefore, require a longer measurement time to achieve the same signal to noise ratio.

text: Wavelength error[edit]

text: In liquids, the extinction coefficient usually changes slowly with wavelength. A peak of the absorbance curve (a wavelength where the absorbance reaches a maximum) is where the rate of change in absorbance with wavelength is smallest.[5] Measurements are usually made at a peak to minimize errors produced by errors in wavelength in the instrument, that is errors due to having a different extinction coefficient than assumed.

text: Stray light[edit]

text: Another important factor is the purity of the light used. The most important factor affecting this is the stray light level of the monochromator.[5]

text: The detector used is broadband; it responds to all the light that reaches it. If a significant amount of the light passed through the sample contains wavelengths that have much lower extinction coefficients than the nominal one, the instrument will report an incorrectly low absorbance. Any instrument will reach a point where an increase in sample concentration will not result in an increase in the reported absorbance, because the detector is simply responding to the stray light. In practice the concentration of the sample or the optical path length must be adjusted to place the unknown absorbance within a range that is valid for the instrument. Sometimes an empirical calibration function is developed, using known concentrations of the sample, to allow measurements into the region where the instrument is becoming non-linear.

text: As a rough guide, an instrument with a single monochromator would typically have a stray light level corresponding to about 3 Absorbance Units (AU), which would make measurements above about 2 AU problematic. A more complex instrument with a double monochromator would have a stray light level corresponding to about 6 AU, which would therefore allow measuring a much wider absorbance range.

text: Deviations from the Beer–Lambert law[edit]

text: At sufficiently high concentrations, the absorption bands will saturate and show absorption flattening. The absorption peak appears to flatten because close to 100% of the light is already being absorbed. The concentration at which this occurs depends on the particular compound being measured. One test that can be used to test for this effect is to vary the path length of the measurement. In the Beer-Lambert law, varying concentration and path length has an equivalent effect—diluting a solution by a factor of 10 has the same effect as shortening the path length by a factor of 10. If cells of different path lengths are available, testing if this relationship holds true is one way to judge if absorption flattening is occurring.

text: Solutions that are not homogeneous can show deviations from the Beer-Lambert law because of the phenomenon of absorption flattening. This can happen, for instance, where the absorbing substance is located within suspended particles (see "Beer's law revisited", Berberan-Santos, J. Chem. Educ. 67 (1990) 757, and "Absorption flattening in the optical spectra of liposome-entrapped substances", Wittung, Kajanus, Kubista, Malmström, FEBS Lett 352 (1994) 37). The deviations will be most noticeable under conditions of low concentration and high absorbance. The last reference describes a way to correct for this deviation.

text: Some solutions, like copper(II)chloride in water, change colour at a certain concentration because of changed conditions around the coloured ion (the divalent copper ion). For copper(II)chloride it means a shift from blue to green,[6] which would mean that monochromatic measurements would deviate from the Beer-Lambert law.

text: Measurement uncertainty sources[edit]

text: The above factors contribute to the measurement uncertainty of the results obtained with UV/Vis spectrophotometry. If UV/Vis spectrophotometry is used in quantitative chemical analysis then the results are additionally affected by uncertainty sources arising from the nature of the compounds and/or solutions that are measured. These include spectral interferences caused by absorption band overlap, fading of the color of the absorbing species (caused by decomposition or reaction) and possible composition mismatch between the sample and the calibration solution.[7]

text: Ultraviolet-visible spectrophotometer[edit]

text:
The instrument used in ultraviolet-visible spectroscopy is called a UV/Vis spectrophotometer. It measures the intensity of light passing through a sample (

I

{\displaystyle I}

), and compares it to the intensity of light before it passes through the sample (

I

o

{\displaystyle I_{o}}

). The ratio

I

/

I

o

{\displaystyle I/I_{o}}

 is called the transmittance, and is usually expressed as a percentage (%T). The absorbance,

A

{\displaystyle A}

, is based on the transmittance:

text:
The UV-visible spectrophotometer can also be configured to measure reflectance. In this case, the spectrophotometer measures the intensity of light reflected from a sample (

I

{\displaystyle I}

), and compares it to the intensity of light reflected from a reference material (

I

o

{\displaystyle I_{o}}

) (such as a white tile). The ratio

I

/

I

o

{\displaystyle I/I_{o}}

 is called the reflectance, and is usually expressed as a percentage (%R).

text: The basic parts of a spectrophotometer are a light source, a holder for the sample, a diffraction grating in a monochromator or a prism to separate the different wavelengths of light, and a detector. The radiation source is often a Tungsten filament (300-2500 nm), a deuterium arc lamp, which is continuous over the ultraviolet region (190-400 nm), Xenon arc lamp, which is continuous from 160-2,000 nm; or more recently, light emitting diodes (LED)[1] for the visible wavelengths. The detector is typically a photomultiplier tube, a photodiode, a photodiode array or a charge-coupled device (CCD). Single photodiode detectors and photomultiplier tubes are used with scanning monochromators, which filter the light so that only light of a single wavelength reaches the detector at one time. The scanning monochromator moves the diffraction grating to "step-through" each wavelength so that its intensity may be measured as a function of wavelength. Fixed monochromators are used with CCDs and photodiode arrays. As both of these devices consist of many detectors grouped into one or two dimensional arrays, they are able to collect light of different wavelengths on different pixels or groups of pixels simultaneously.

text:
A spectrophotometer can be either single beam or double beam. In a single beam instrument (such as the Spectronic 20), all of the light passes through the sample cell.

I

o

{\displaystyle I_{o}}

 must be measured by removing the sample. This was the earliest design and is still in common use in both teaching and industrial labs.

text: In a double-beam instrument, the light is split into two beams before it reaches the sample. One beam is used as the reference; the other beam passes through the sample. The reference beam intensity is taken as 100% Transmission (or 0 Absorbance), and the measurement displayed is the ratio of the two beam intensities. Some double-beam instruments have two detectors (photodiodes), and the sample and reference beam are measured at the same time. In other instruments, the two beams pass through a beam chopper, which blocks one beam at a time. The detector alternates between measuring the sample beam and the reference beam in synchronism with the chopper. There may also be one or more dark intervals in the chopper cycle. In this case, the measured beam intensities may be corrected by subtracting the intensity measured in the dark interval before the ratio is taken.

text:
Samples for UV/Vis spectrophotometry are most often liquids, although the absorbance of gases and even of solids can also be measured. Samples are typically placed in a transparent cell, known as a cuvette. Cuvettes are typically rectangular in shape, commonly with an internal width of 1 cm. (This width becomes the path length,

L

{\displaystyle L}

, in the Beer-Lambert law.) Test tubes can also be used as cuvettes in some instruments. The type of sample container used must allow radiation to pass over the spectral region of interest. The most widely applicable cuvettes are made of high quality fused silica or quartz glass because these are transparent throughout the UV, visible and near infrared regions. Glass and plastic cuvettes are also common, although glass and most plastics absorb in the UV, which limits their usefulness to visible wavelengths.[1]

text: Specialized instruments have also been made. These include attaching spectrophotometers to telescopes to measure the spectra of astronomical features. UV-visible microspectrophotometers consist of a UV-visible microscope integrated with a UV-visible spectrophotometer.

text: A complete spectrum of the absorption at all wavelengths of interest can often be produced directly by a more sophisticated spectrophotometer. In simpler instruments the absorption is determined one wavelength at a time and then compiled into a spectrum by the operator. By removing the concentration dependence, the extinction coefficient (ε) can be determined as a function of wavelength.

text: Microspectrophotometry[edit]

text: UV-visible spectroscopy of microscopic samples is done by integrating an optical microscope with UV-visible optics, white light sources, a monochromator, and a sensitive detector such as a charge-coupled device (CCD) or photomultiplier tube (PMT). As only a single optical path is available, these are single beam instruments. Modern instruments are capable of measuring UV-visible spectra in both reflectance and transmission of micron-scale sampling areas. The advantages of using such instruments is that they are able to measure microscopic samples but are also able to measure the spectra of larger samples with high spatial resolution. As such, they are used in the forensic laboratory to analyze the dyes and pigments in individual textile fibers,[8] microscopic paint chips [9] and the color of glass fragments. They are also used in materials science and biological research and for determining the energy content of coal and petroleum source rock by measuring the vitrinite reflectance. Microspectrophotometers are used in the semiconductor and micro-optics industries for monitoring the thickness of thin films after they have been deposited. In the semiconductor industry, they are used because the critical dimensions of circuitry is microscopic. A typical test of a semiconductor wafer would entail the acquisition of spectra from many points on a patterned or unpatterned wafer. The thickness of the deposited films may be calculated from the interference pattern of the spectra. In addition, ultraviolet-visible spectrophotometry can be used to determine the thickness, along with the refractive index and extinction coefficient of thin films as described in Refractive index and extinction coefficient of thin film materials. A map of the film thickness across the entire wafer can then be generated and used for quality control purposes.[10]

text: Additional applications[edit]

text: UV/Vis can be applied to determine the kinetics or rate constant of a chemical reaction. The reaction, occurring in solution, must present color or brightness shifts from reactants to products in order to use UV/Vis for this application.[2] For example, the molecule mercury dithizonate is a yellow-orange color in diluted solution (1*10^-5 M), and turns blue when subjected with particular wavelengths of visible light (and UV) via a conformational change, but this reaction is reversible back into the yellow "ground state".[11]

text: The rate constant of a particular reaction can be determined by measuring the UV/Vis absorbance spectrum at specific time intervals. Using mercury dithizonate again as an example, one can shine light on the sample to turn the solution blue, then run a UV/Vis test every 10 seconds (variable) to see the levels of absorbed and reflected wavelengths change over time in accordance with the solution turning back to yellow from the excited blue energy state. From these measurements, the concentration of the two species can be calculated.[12] The mercury dithizonate reaction from one conformation to another is first order and would have the integral first order rate law : ln[A](time t)=−kt+ln[A](initial). Therefore, graphing the natural log (ln) of the concentration [A] versus time will graph a line with slope -k, or negative the rate constant. Different rate orders have different integrated rate laws depending on the mechanism of the reaction.

text: An equilibrium constant can also be calculated with UV/Vis spectroscopy. After determining optimal wavelengths for all species involved in equilibria, a reaction can be run to equilibrium, and the concentration of species determined from spectroscopy at various known wavelengths. The equilibrium constant can be calculated as K(eq) = [Products] / [Reactants].