What are the chief characters of the crustaceans ?

Explanation

1). This includes prawns, crabs, lobsters, cray fishes etc.
2) Mostly marine, a few are fresh water and some are adapted to terrestirial life.
3) In most species, head and thorax fuse to form cephalo - thorax.
4) Cephalic appendages are five pairs - first antennae Prawn (antennules) second antennae, mandibles, first maxillae and second maxillae.
5) Thoracic and abdominal appendages are typically biramous.
6) Respiration is by gi!ls.
7) Excretory organs are green glands or antennal glands.
8) Sense organs include statocysts, compound eyes and antennae.
9) .Gonopores are paired.
10) Development is direct or indirect involving several larval stages. Basic larva is nauplius.