Malacostraca
Leptostraca
Stomatopoda
Bathynellacea
Thermosbaenacea
Mysidacea
Cumacea
Amphipoda
Isopoda
Tanaidacea
Euphausiacea
Amphionidacea
Decapoda
Peracarida
</table>
The
Malacostraca are the largest subgroup of
crustaceans, and include most of the animals that non-experts recognise as crustaceans, including the
decapods (such as
crabs,
mole crabs,
lobsters and true
shrimps), the stomatopods or
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
