Prawn or Shrimp: Confused?
Wednesday, March 14, 2012
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Freshwater Prawn And Shrimp Farming
Shrimp are swimming, decapods crustaceans widely distributed in both fresh as well as marine waters and are the members of the infraorder Caridea. The word shrimp comes from an Old English word. Adults are filter feeding benthic animals living close to the bottom. They prefer to live in schools and can swim even backwards. They form an important part of food of animals like fishes as well as whales. They can tolerate highly toxic waters and can also contribute to high toxin levels in the predators. Along with prawns they are highly caught and farmed on commercial basis. The class Malacostraca contains about half of the crustaceans. The members of this class bear primitive 5-8-7 body plan like that of a shrimp. They bear small carapace which protects the head and thorax underneath. Abdomen is muscular basically used for swimming. The exoskeleton is thin maintaining light weight of the body. These features are common in all members of this class.
They may be further classified into decapods which may be either dendrobranchaite or carideans. They have sequentially overlapping body segments, first two pairs of legs are chelate and the body resembles a larva. In prawns the first three pairs of legs are chelate. True shrimps can be isolated from the true prawns of the basis of their gill structures. The gill structure is lamellar in shrimps while it is branching in the prawns. The easiest method to differentiate a true shrimp and a true prawn is observing the second abdominal segment. The second segment overlaps the first and third segment in true shrimps while in prawns the second segments overlaps only the third segment. Although both resemble very closely they are kept in different suborders of order Decapoda.
In the United Kingdom prawn is more frequently consumed than shrimp while condition is reverse in North America. Shrimps are good sources of calcium, iodine and proteins but low food energy. A shrimp based meal also contains significant levels of cholesterol ranging from 122 mg-251 mg per 100 g of shrimp. Shrimp consumption is however considered healthy for the circulatory system as it lacks significant levels of saturated fats. It lowers the triglyceride levels. Shrimp and shellfish are most common food allergens. Otter trawls, cast nets, dip nets and shrimp baiting is chiefly employed for capturing them. Along the coasts of Pacific Northwest bait traps are frequently used for catching them. Shrimp are important constituents of aquaculture. The commercial production of shrimp by aquaculture started in the 1970s and increased rapidly to fulfill the demand of people of America, Japan and Western Europe. The global production of shrimp reached 1.6 million tonnes in 2003.
They are marketed in different ways like they may be frozen, graded and even coloured. They are prepared by removing the shell, tail, sand vein and head. The shell can be removed by holding the tail gently. The removal of vein is called as deveining although they lack true veins as they don't have a close circulatory system. Then they can be baked, fried, boiled or grilled. They are important constituents of cuisine of many nations. Most species tend to breed and attain maturity only in marine habitats although a small proportion of freshwater species is also known. The female lays about 50,000-1 million eggs that hatch within 24 hours into tiny nauplii. These nauplii feed on the yolk contents within their body and then metamorphose into zoeae. This stage feed on algae and then after few days gets converted into another larval stage called mysis. This stage resembles somewhat like that of the adult and feeds on algae and zoo plankton. After three to four they finally metamorphose into adults. The whole cycle takes about 12 days from hatching. Most common species are pink, brown and snapping shrimp. Depending on the species and environmental conditions they attain a length of 1.2-30 centimeters with an average lifespan of 6.5 years. The fossil record of only 57 species is known that belong to Lower Jurassic and Cretaceous Period. Some species are also kept in aquaria for removing algae and other debris.
Shrimp are swimming, decapods crustaceans widely distributed in both fresh as well as marine waters and are the members of the infraorder Caridea. The word shrimp comes from an Old English word. Adults are filter feeding benthic animals living close to the bottom. They prefer to live in schools and can swim even backwards. They form an important part of food of animals like fishes as well as whales. They can tolerate highly toxic waters and can also contribute to high toxin levels in the predators. Along with prawns they are highly caught and farmed on commercial basis. The class Malacostraca contains about half of the crustaceans. The members of this class bear primitive 5-8-7 body plan like that of a shrimp. They bear small carapace which protects the head and thorax underneath. Abdomen is muscular basically used for swimming. The exoskeleton is thin maintaining light weight of the body. These features are common in all members of this class.
They may be further classified into decapods which may be either dendrobranchaite or carideans. They have sequentially overlapping body segments, first two pairs of legs are chelate and the body resembles a larva. In prawns the first three pairs of legs are chelate. True shrimps can be isolated from the true prawns of the basis of their gill structures. The gill structure is lamellar in shrimps while it is branching in the prawns. The easiest method to differentiate a true shrimp and a true prawn is observing the second abdominal segment. The second segment overlaps the first and third segment in true shrimps while in prawns the second segments overlaps only the third segment. Although both resemble very closely they are kept in different suborders of order Decapoda.
In the United Kingdom prawn is more frequently consumed than shrimp while condition is reverse in North America. Shrimps are good sources of calcium, iodine and proteins but low food energy. A shrimp based meal also contains significant levels of cholesterol ranging from 122 mg-251 mg per 100 g of shrimp. Shrimp consumption is however considered healthy for the circulatory system as it lacks significant levels of saturated fats. It lowers the triglyceride levels. Shrimp and shellfish are most common food allergens. Otter trawls, cast nets, dip nets and shrimp baiting is chiefly employed for capturing them. Along the coasts of Pacific Northwest bait traps are frequently used for catching them. Shrimp are important constituents of aquaculture. The commercial production of shrimp by aquaculture started in the 1970s and increased rapidly to fulfill the demand of people of America, Japan and Western Europe. The global production of shrimp reached 1.6 million tonnes in 2003.
They are marketed in different ways like they may be frozen, graded and even coloured. They are prepared by removing the shell, tail, sand vein and head. The shell can be removed by holding the tail gently. The removal of vein is called as deveining although they lack true veins as they don't have a close circulatory system. Then they can be baked, fried, boiled or grilled. They are important constituents of cuisine of many nations. Most species tend to breed and attain maturity only in marine habitats although a small proportion of freshwater species is also known. The female lays about 50,000-1 million eggs that hatch within 24 hours into tiny nauplii. These nauplii feed on the yolk contents within their body and then metamorphose into zoeae. This stage feed on algae and then after few days gets converted into another larval stage called mysis. This stage resembles somewhat like that of the adult and feeds on algae and zoo plankton. After three to four they finally metamorphose into adults. The whole cycle takes about 12 days from hatching. Most common species are pink, brown and snapping shrimp. Depending on the species and environmental conditions they attain a length of 1.2-30 centimeters with an average lifespan of 6.5 years. The fossil record of only 57 species is known that belong to Lower Jurassic and Cretaceous Period. Some species are also kept in aquaria for removing algae and other debris.
Navodita Maurice