Among the marine edible crustaceans, crabs occupy third position by virtue of its
delicacy, demand and price. the first two being shrimps and lobsters. Among the 990 species of
marine crabs, 34 species are growing to larger size and hence they fetch a higher price. Most of
the commercially important crabs belonged to the family Portunidae and they can be recognized
by the presence of flattened last pair of legs, which help them in swimming in the columnar
Haters. Species belonging to genera Scylla, Portunus and Chaq-bdis which grow.to 0.2 to 2.3 kg
are considered as commercially important portunid crabs as they are utilized for both local
consumption and export trade.