Practice question

Malacostraca represents dominant and most diverse crustacean class incorporating familiar decapods like brachyuran crabs, lobsters, shrimps and prawns plus peracarids such as amphipods and isopods and euphausiaceans krill. Body plan consists of 8 thoracic segments forming thorax covered partially or fully by carapace, 6 abdominal segments plus telson, pleopods and gills. Branchiopoda includes fairy shrimp and cladocerans, Ostracoda bean-like bivalved forms, Copepoda tiny copepods dominating zooplankton. Malacostracan ecological success attributes to carapace protection, efficient gill respiration and versatile appendage specialization supporting benthic, pelagic and terrestrial niches.