Shrimp

Females of the freshwater shrimp Caridina ensifera are capable of storing sperm from multiple partners, and thus can produce progeny with different paternities.[27] Reproductive success of sires was found to correlate inversely with their genetic relatedness to the mother.[27] This finding suggests that sperm competition and/or pre- and post-copulatory female choice occurs. Female choice may increase the fitness of progeny by reducing inbreeding depression that ordinarily results from the expression of homozygous deleterious recessive mutations.[28]

There is little agreement among taxonomists concerning the phylogeny of crustaceans.[29] Within the decapods "every study gives totally different results. Nor do even one of these studies match any of the rival morphology studies".[30] Some taxonomists identify shrimp with the infraorder Caridea and prawns with the suborder Dendrobranchiata.[31] While different experts give different answers, there is no disagreement that the caridean species are shrimp.[3] There are over 3000 caridean species.[32] Occasionally they are referred to as "true shrimp".[33]

Traditionally decapods were divided into two suborders: the Natantia (or swimmers), and the Reptantia (or walkers). The Natantia or swimmers included the shrimp. They were defined by their abdomen which, together with its appendages was well adapted for swimming. The Reptantia or walkers included the crabs and lobsters. These species have small abdominal appendages, but robust legs well adapted for walking. The Natantia was thought to be paraphyletic, that is, it was thought that originally all decapods were like shrimp.[34]

However, classifications are now based on clades, and the paraphyletic suborder Natantia has been discontinued. "On this basis, taxonomic classifications now divide the order Decapoda into the two suborders: Dendrobranchiata for the largest shrimp clade, and Pleocyemata for all other decapods. The Pleocyemata are in turn divided into half a dozen infra-orders"[34]

• The taxonomists De Grave and Fransen, 2011, recognise four major groups of shrimp: the suborder Dendrobranchiata and the infraorders Procarididea, Stenopodidea and Caridea".[35] This group is identical to the traditional Natantia group, and contains decapods only.
• All shrimp of commercial interest belong to the Natantia. The FAO determine the categories and terminology used in the reporting of global fisheries. They define a shrimp as a "decapod crustacean of the suborder Natantia".[36]
• According to the Codex Alimentarius Commission of the FAO and WHO: "The term shrimp (which includes the frequently used term prawn) refers to the species covered by the most recent edition of the FAO listing of shrimp, FAO Species Catalogue, Volume 1, Shrimps and prawns of the world, an annotated catalogue of species of interest to fisheries FAO Fisheries Synopsis No. 125."[37] In turn, the Species Catalogue says the highest category it deals with is "the suborder Natantia of the order Crustacea Decapoda to which all shrimps and prawns belong".[38]

Major shrimp groups of the Natantia
Order	Suborder	Infraorder	Image	Extant species [32]	Description
Decapoda	Dendrobranchiata			533	Penaeid shrimp A particularly significant family in this suborder is the Penaeidae, often referred to as penaeid shrimp or penaeid prawn. Most commercially important species are in this family. See below. The species in this suborder tend to be larger than the caridean shrimp species below, and many are commercially important. They are sometimes referred to as prawns. Dendrobranchiata, such as the giant tiger prawn pictured, typically have three pairs of claws, though their claws are less conspicuous than those of other shrimp. They do not brood eggs like the caridean, but shed them directly into the water. Their gills are branching, whereas the gills of caridean shrimp are lamellar. The segments on their abdomens are even-sized, and there is no pronounced bend in the abdomen.[3][6][13][39]
	Pleocyemata	Caridea		3438	The numerous species in this infraorder are known as caridean shrimp, though only a few are commercially important. They are usually small, nocturnal, difficult to find (they burrow in the sediment), and of interest mainly to marine biologists. Caridean shrimp, such as the pink shrimp pictured, typically have two pairs of claws. Female carideans attach eggs to their pleopods and brood them there. The second abdominal segment overlaps both the first and the third segment, and the abdomen shows a pronounced caridean bend.[3][9][39][40]
		Procarididea		6	A minor sister group to the Caridea (immediately above)
		Stenopodidea		71	Known as boxer shrimp, the members of this infraorder are often cleaner shrimp. Their third pair of walking legs (pereiopods) are greatly enlarged. The banded coral shrimp (pictured) is popular in aquariums. The Stenopodidea are a much smaller group than the Dendrobranchia and Caridea, and have no commercial importance.[41]

Other decapod crustaceans also called shrimp, are the ghost or mud shrimp belonging to the infra-order Thalassinidea. In Australia they are called yabbies.[42] The monophyly of the group is not certain; recent studies have suggested dividing the group into two infraorders, Gebiidea and Axiidea.[35]

A wide variety of non-decapod crustaceans are also commonly referred to as shrimp. This includes the brine shrimp, clam shrimp, fairy shrimp and tadpole shrimp belonging to the branchiopods, the lophogastridan shrimp, opossum shrimp and skeleton shrimp belonging the Malacostraca; and seed shrimp which are ostracods.[3] Many of these species look quite unlike the commercial decapod shrimp that are eaten as seafood. For example, skeleton shrimp have short legs and a slender tail like a scorpion tail, fairy shrimp swim upside down with swimming appendages that look like leaves, and the tiny seed shrimp have bivalved carapaces which they can open or close.[12] Krill resemble miniature shrimp, and are sometimes called "krill shrimp".[43][44]

Other species groups commonly known as shrimp
Class	Image	Group	Extant species	Description
Branchiopoda	Branchiopoda comes from the Greek branchia meaning gills, and pous meaning feet.[45] They have gills on their feet or mouthparts.[46]
		brine shrimp	8	Brine shrimp belong to the genus Artemia. They live in inland saltwater lakes in unusually high salinities, which protects them from most predators. They produce eggs, called cysts, which can be stored in a dormant state for long periods and then hatched on demand. This has led to the extensive use of brine shrimp as fish feed in aquaculture.[47] Brine shrimp are sold as novelty gifts under the marketing name Sea-Monkeys.
		clam shrimp	150	Clam shrimp belong to the group Conchostraca. These freshwater shrimp have a hinged bivalved carapace which can open and close.
		fairy shrimp	300	Fairy shrimp belong to the class Anostraca. These 1–10 cm long freshwater or brackish shrimp have no carapace. They swim upside down with their belly uppermost, with swimming appendages that look like leaves. Most fairy shrimp are herbivores, and eat only the algae in the plankton. Their eggs can survive drought and temperature extremes for years, reviving and hatching after the rain returns.[48]
		tadpole shrimp	20	Tadpole shrimp belong to the family Notostraca. These living fossils have not much changed since the Triassic. They are drought-resistant and can be found preying on fairy shrimp and small fish at the bottom of shallow lakes and temporary pools.[49] The longtail tadpole shrimp (pictured) has three eyes and up to 120 legs with gills on them.[50] It lives for 20–90 days. Different populations can be bisexual, unisexual or hermaphroditic.
Malacostraca	Malacostraca comes from the Greek malakós meaning soft and óstrakon meaning shell.[51] The name is misleading, since normally the shell is hard, and is soft only briefly after moulting.[52]
		Lophogastrida	56	These marine pelagic shrimp make up the order Lophogastrida. They mostly inhabit relatively deep pelagic waters throughout the world. Like the related opossum shrimp, females lophogastrida carry a brood pouch.[53]
		mantis shrimp	400	Mantis shrimp, so called because they resemble a praying mantis, make up the order Stomatopoda. They grow up to 38 cm (15 in) long, and can be vividly coloured. Some have powerful spiked claws which they punch into their prey, stunning, spearing and dismembering them. They have been called "thumb splitters" because of the severe gashes they can inflict if handled carelessly.[54]
		opossum shrimp	1,000	Opossum shrimp belong to the order Mysida. They are called opossum shrimp because the females carry a brood pouch. Usually less than 3 cm long, they are not closely related to caridean or penaeid shrimp. They are widespread in marine waters, and are also found in some brackish and freshwater habitats in the Northern hemisphere. Marine mysids can form large swarms and are an important source of food for many fish. Some freshwater mysids are found in groundwater and anchialine caves.[53][55]
		skeleton shrimp		Skeleton shrimp, sometimes known as ghost shrimp, are amphipods. Their threadlike slender bodies allow them to virtually disappear among fine filaments in seaweed. Males are usually much larger than females.[56][57] For a good account of a specific species, see Caprella mutica.
Ostracoda	Ostracod comes from the Greek óstrakon meaning shell. In this case, the shells are in two parts, like those of bivalves or clams.
		seed shrimp	13,000	Seed shrimp make up the class Ostracoda. This is a class of numerous small crustacean species which look like seeds, typically about one millimetre (0.04 in) in size. Their carapace looks like a clam shell, with two parts held together by a hinge to allow the shell to open and close. Some marine seed shrimp drift as pelagic plankton, but most live on the sea floor and burrow in the upper sediment layer. There are also freshwater and terrestrial species. The class includes carnivores, herbivores, filter feeders and scavengers.[58]

Some mantis shrimp are a foot long, and have bulging eyes, a flattened tail and formidable claws equipped with clubs or sharp spikes, which it can use to knock out its opponents.[12][54]

Examples of non-decapod "shrimp"

Some mantis shrimp knock prey out with powerful punches, and can crack a clam open.[12][54]

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Mantis Shrimp Destroys Clam – YouTube

Skeleton shrimp have threadlike slender bodies

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Skeleton shrimp – YouTube

Tadpole shrimp can have up to 120 swimming legs

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Triops – YouTube

Some branchiopods, like this brine shrimp, have eggs which survive prolonged drought conditions.

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Branchiopod shrimp – YouTube

The Shrimp Girl by William Hogarth, circa 1740–1745, balances on her head a large basket of shrimp and mussels, which she is selling on the streets of London

Commercial production of shrimps (and prawns) in million tonnes as reported by the FAO, 1950–2009[59]

In 1991, archeologists suggested that ancient raised paved areas near the coast in Chiapas, Mexico, were platforms used for drying shrimp in the sun, and that adjacent clay hearths were used to dry the shrimp when there was no sun.[60][61] The evidence was circumstantial, because the chitinous shells of shrimp are so thin they degrade rapidly, leaving no fossil remains. In 1985 Quitmyer and others found direct evidence dating back to 600 AD for shrimping off the southeastern coast of North America, by successfully identifying shrimp from the archaeological remains of their mandibles (jaws).[62][63][64] Clay vessels with shrimp decorations have been found in the ruins of Pompeii.[64] In the 3rd century AD, the Greek author Athenaeus wrote in his literary work, Deipnosophistae; "... of all fish the daintiest is a young shrimp in fig leaves."[65]

In North America, indigenous peoples of the Americas captured shrimp and other crustaceans in fishing weirs and traps made from branches and Spanish moss, or used nets woven with fibre beaten from plants. At the same time early European settlers, oblivious to the "protein-rich coasts" all about them, starved from lack of protein.[64] In 1735 beach seines were imported from France, and Cajun fishermen in Louisiana started catching white shrimp and drying them in the sun, as they still do today.[64] In the mid nineteenth century, Chinese immigrants arrived for the California Gold Rush, many from the Pearl River Delta where netting small shrimp had been a tradition for centuries. Some immigrants starting catching shrimp local to San Francisco Bay, particularly the small inch long Crangon franciscorum. These shrimp burrow into the sand to hide, and can be present in high numbers without appearing to be so. The catch was dried in the sun and was exported to China or sold to the Chinese community in the United States.[64] This was the beginning of the American shrimping industry. Overfishing and pollution from gold mine tailings resulted in the decline of the fishery. It was replaced by a penaeid white shrimp fishery on the South Atlantic and Gulf coasts. These shrimp were so abundant that beaches were piled with windrows from their moults. Modern industrial shrimping methods originated in this area.[64]

""For shrimp to develop into one of the world's most popular foods, it took the simultaneous development of the otter trawl... and the internal combustion engine."[64] Shrimp trawling can capture shrimp in huge volumes by dragging a net along the seafloor. Trawling was first recorded in England in 1376, when King Edward III received a request that he ban this new and destructive way of fishing.[66] In 1583, the Dutch banned shrimp trawling in estuaries.[67]

In the 1920s, diesel engine were adapted for use in shrimp boats. Power winches were connected to the engines, and only small crews were needed to rapidly lift heavy nets on board and empty them. Shrimp boats became larger, faster, and more capable. New fishing grounds could be explored, trawls could be deployed in deeper offshore waters, and shrimp could be tracked and caught round the year, instead of seasonally as in earlier times. Larger boats trawled offshore and smaller boats worked bays and estuaries. By the 1960s, steel and fibreglass hulls further strengthened shrimp boats, so they could trawl heavier nets, and steady advances in electronics, radar, sonar, and GPS resulted in more sophisticated and capable shrimp fleets.[64]

As shrimp fishing methods industrialised, parallel changes were happening in the way shrimp were processed. "In the 19th century, sun dried shrimp were largely replaced by canneries. In the 20th century, the canneries were replaced with freezers."[64]

In the 1970s, significant shrimp farming was initiated, particularly in China. The farming accelerated during the 1980s as the quantity of shrimp demand exceeded the quantity supplied, and as excessive bycatch and threats to endangered sea turtle became associated with trawling for wild shrimp.[64] In 2007, the production of farmed shrimp exceeded the capture of wild shrimp.[59]

Although there are thousands of species of shrimp worldwide, only about 20 of these species are commercially significant. The following table contains the principal commercial shrimp, the seven most harvested species. All of them are decapods; most of them belong to the Dendrobranchiata and four of them are penaeid shrimp.

Double-rigged shrimp trawler with one net up and the other being brought aboard

Traditional shrimper with a shrimp net

Global wild capture, 1950–2010, in million tonnes, as reported by the FAO [59]

Commercial techniques for catching wild shrimp include otter trawls, seines and shrimp baiting. A system of nets is used when trawling. Baited traps are common in parts of the Pacific Northwest.

Shrimp trawling can result in very high incidental catch rates of non-target species. In 1997, the FAO found discard rates up to 20 pounds for every pound of shrimp. The world average was 5.7 pounds for every pound of shrimp.[92] Trawl nets in general, and shrimp trawls in particular, have been identified as sources of mortality for species of finfish and cetaceans.[93] Bycatch is often discarded dead or dying by the time it is returned to the sea, and may alter the ecological balance in discarded regions.[94] Worldwide, shrimp trawl fisheries generate about 2% of the world's catch of fish in weight, but result in more than one third of the global bycatch total.

The most extensively fished species are the akiami paste shrimp, the northern prawn, the southern rough shrimp, and the giant tiger prawn. Together these four species account for nearly half of the total wild capture. In recent years, the global capture of wild shrimp has been overtaken by the harvest from farmed shrimp.[59]

Tanks in a shrimp hatchery

The whiteleg shrimp (juvenile shown) has become the preferred species for shrimp farming.

Global aquaculture production 1970–2009, in million tonnes, as reported by the FAO [59]

A shrimp farm is an aquaculture business for the cultivation of marine shrimp or prawns for human consumption. Commercial shrimp farming began in the 1970s, and production grew steeply, particularly to match the market demands of the United States, Japan and Western Europe. The total global production of farmed shrimp reached more than 1.6 million tonnes in 2003, representing a value of nearly 9 billion U.S. dollars. About 75% of farmed shrimp are produced in Asia, in particular in China, Thailand, Indonesia, India and Vietnam. The other 25% are produced mainly in Latin America, where Brazil is the largest producer. By 2016, the largest exporting nation is India, followed by Ecuador, Thailand, Indonesia and China.[95]

As can be seen from the global production chart on the left, significant aquaculture production started slowly in the 1970s and then rapidly expanded during the 1980s. After a lull in growth during the 1990s, due to pathogens, production took off again and by 2007 exceeded the capture from wild fisheries. By 2010, the aquaculture harvest was 3.9 million tonnes, compared to 3.1 million tonnes for the capture of wild shrimp.[59]

In the earlier years of marine shrimp farming the preferred species was the large giant tiger prawn. This species is reared in circular holding tanks where they think they are in the open ocean, and swim in "never ending migration" around the circumference of the tank.[96] In 2000, global production was 630,984 tonnes, compared to only 146,362 tonnes for whiteleg shrimp. Subsequently, these positions reversed, and by 2010 the production of giant tiger prawn increased modestly to 781,581 tonnes while whiteleg shrimp rocketed nearly twenty-fold to 2,720,929 tonnes.[59] The whiteleg shrimp is currently the dominant species in shrimp farming. It is a moderately large shrimp reaching a total length of 230 mm (9"), and is particularly suited to farming because it "breeds well in captivity, can be stocked at small sizes, grows fast and at uniform rates, has comparatively low protein requirements... and adapts well to variable environmental conditions."[97] In China, prawns are cultured along with sea cucumbers and some fish species, in integrated multi-trophic systems.

The major producer of farmed shrimp is China. Other significant producers are Thailand, Indonesia, India, Vietnam, Brazil, Ecuador and Bangladesh. Most farmed shrimp is exported to the United States, the European Union and Japan,[98] also other Asian markets, including South Korea, Hong Kong, Taiwan and Singapore.[95]

Investigations by The Guardian in 2014 and The Associated Press in 2015 found human rights abuses on fishing boats operated by Thailand. The boats are manned with slaves, and catch shrimp and fish (including fish for the production of fishmeal which is fed to farmed prawns).[99][100] Greenpeace has challenged the sustainability of tropical shrimp farming practices on the grounds that farming these species "has led to the destruction of vast areas of mangroves in several countries [and] over-fishing of juvenile shrimp from the wild to supply farms." Greenpeace has placed a number of the prominent tropical shrimp species that are farmed commercially on its seafood red list, including the whiteleg shrimp, Indian prawn and giant tiger shrimp.[101]

Shrimp tail ready for eating

Wikibooks Cookbook has a recipe/module on shrimp

Shrimp are marketed and commercialized with several issues in mind. Most shrimp are sold frozen and marketed based on their categorization of presentation, grading, colour, and uniformity.[102] Shrimp have high levels of omega-3 fatty acids and low levels of mercury.[103] Usually shrimp is sold whole, though sometimes only the meat of shrimp is marketed.

As with other seafood, shrimp is high in calcium, iodine and protein but low in food energy. A shrimp-based meal is also a significant source of cholesterol, from 122 mg to 251 mg per 100 g of shrimp, depending on the method of preparation.[104] Shrimp consumption, however, is considered healthy for the circulatory system because the lack of significant levels of saturated fat in shrimp means that the high cholesterol content in shrimp actually improves the ratio of LDL to HDL cholesterol and lowers triglycerides.[105]

Ebiko - shrimp roe, sometimes translated as "shrimp flakes" - is used as one of the ingredients in the preparation of sushi.[106]

Shrimp and other shellfish are among the most common food allergens.[107] They are not kosher and thus are forbidden in Jewish cuisine.

Several types of shrimp are kept in home aquaria. Some are purely ornamental, while others are useful in controlling algae and removing debris.[108] Freshwater shrimp commonly available for aquaria include the Bamboo shrimp, Japanese marsh shrimp (Caridina multidentata, also called "Amano shrimp," as their use in aquaria was pioneered by Takashi Amano), cherry shrimp (Neocaridina heteropoda), and ghost or glass shrimp (Palaemonetes spp.). Popular saltwater shrimp include the cleaner shrimp Lysmata amboinensis, the fire shrimp (Lysmata debelius) and the harlequin shrimp (Hymenocera picta).

Freshwater aquaria variant shrimp come in many colours

The Caridina cantonensis snow white shrimp is a white freshwater shrimp. The "Neocaridina heteropoda var. red" cherry shrimp is particularly easy to keep and breed. The "Neocaridina zhanghjiajiensis var. blue" pearl shrimp is closely related to the cherry shrimp. The Caridina cantonensis tiger shrimp is transparent with black stripes. The Caridina cantonensis red tiger shrimp is transparent with red stripes and is found in southern China. The popular Caridina cantonensis crystal red bee shrimp has broad red and white stripes.