Malacostraca
Scientific classification
Kingdom:Animalia
Phylum:Arthropoda
Subphylum:Crustacea
Class :Malacostraca
Orders
not necessarily a complete list:
Leptostraca
Stomatopoda
Bathynellacea
Thermosbaenacea
Mysidacea
Cumacea
Amphipoda
Isopoda
Tanaidacea
Euphausiacea
Amphionidacea
Decapoda
Peracarida
The Malacostraca are the largest subgroup of crustaceans, and include most of the animals that non-experts recognise as crustaceans, including crabs, lobsters, shrimps, mantis shrimps and krill. They also include the huge group of amphipods, and the only substantial group of land-based crustaceans, the isopods (woodlice or sowbugs and related species).

The classification of crustaceans is currently being debated, and the Malacostraca are regarded by some authors as a class and by others as a subclass.

Their characteristics include:

  • Five pairs of walking legs
  • The first pair of legs are often modified to form pincers
  • Cephalothorax covered by a carapace
  • Abdomen behind, often used for swimming
  • Appendages near the mouth; these are called maxillipeds
  • Two-chambered stomach
  • Centralised nervous system