Malacostraca

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Wikipedia:How to read a taxobox
How to read a taxobox
Malacostraca
Eophreatoicus, a fresh water isopod from Australia.
Eophreatoicus, a fresh water isopod from Australia.
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Crustacea
Class: Malacostraca
Latreille, 1802
Subclasses

Eumalacostraca
Hoplocarida
Phyllocarida
See text for orders.

The Malacostraca (Greek: "soft shell") are the largest subgroup of crustaceans and include most of the animals that non-experts recognise as crustaceans, including decapods (such as crabs, lobsters and shrimp), stomatopods (mantis shrimp) and krill. They also include the amphipods and the only substantial group of land-based crustaceans, the isopods (woodlice and related species). With more than 22,000 members, this group represents two thirds of all crustacean species and contains all the larger forms. The first malacostracans appeared in the Cambrian.

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.

[edit] Morphology

General malacostracan Bauplan
General malacostracan Bauplan

Their characteristics include:

  • The head has 6 segments, with a pair of antennules and a pair of antennae, as well as mouthparts.
  • They have 5 pairs of walking legs, with the first often modified to form pincers.
  • There are 8 thoracic segments. The cephalothorax is covered by a carapace form via fusion of 3 of them, letting the 5 other uncovered.
  • The abdomen is behind and often used for swimming. There are 6 abdominal segments.
  • There are appendages near the mouthparts, these are called maxillipeds.
  • They have compound stalked or sessile eyes.
  • They have a two-chambered stomach.
  • They have a centralised nervous system.

[edit] Classification

Martin and Davis[1] present the following classification of living malacostracans into orders, to which extinct orders have been added, indicated by †.

Lysiosquilla maculata, a mantis shrimp
Lysiosquilla maculata, a mantis shrimp

Class Malacostraca Latreille, 1802

[edit] References

  1. ^ Joel W. Martin and George E. Davis (2001). An Updated Classification of the Recent Crustacea. Natural History Museum of Los Angeles County. 
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