Decapod

Decapoda is an order of crustaceans in the class Malacostraca. Many familiar groups, such as crayfish, crabs, lobsters, prawns and shrimp are in this order. Many decapods are scavengers - they eat dead plants and animals. Crabs are mixed feeders, taking algae and shellfish such as molluscs. Lobsters eat mostly live prey.

Decapoda
"Decapoda" from Ernst Haeckel's Artforms of Nature, 1904
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Crustacea
Class:	Malacostraca
Superorder:	Eucarida
Order:	Decapoda Latreille, 1802
Suborders
Dendrobranchiata Pleocyemata

Anatomy

As their name suggests, all decapods have ten appendages.

The last five pairs of appendages on the front half of the body, the cephalothorax, are used for walking.^[1]

In many decapods, the front pair of appendages carry large pinching claws. The claws are called chelae, so these appendages may be called chelipeds.

The front three pairs of appendages on the thorax are used as jaws, and called maxillipeds.

On the abdomen are swimming appendages called pleopods, and the body ends in a tail fan.

Classification

Classification of the order Decapoda depends on the structure of the gills and legs, and the way in which the larvae develop. There are two suborders: Dendrobranchiata and Pleocyemata. Prawns (including many so-called "shrimp", such as the Atlantic white shrimp) make up the Dendrobranchiata. The other groups, including true shrimp, are the Pleocyemata.

The following classification follows Martin and Davis,^[2] with some changes based on more recent structural and molecular studies.^[3][4]x

Order Decapoda Latreille, 1802 (Selection, not everything is listed)

• Suborder Dendrobranchiata Bate, 1888 – prawns
• Suborder Pleocyemata Burkenroad, 1963
  • Infraorder Caridea Dana, 1852 – true shrimp
  • Infraorder Achelata Scholtz & Richter, 1995 – spiny lobsters, slipper lobsters, and furry lobsters
  • Infraorder Astacidea Latreille, 1802 – lobsters and crayfish
  • Infraorder Anomura MacLeay, 1838
    • Superfamily Galatheoidea Samouelle, 1819 – squat lobsters
    • Superfamily Paguroidea Latreille, 1802 – hermit crabs
  • Infraorder Brachyura Latreille, 1802 – crabs

• 
  Whiteleg shrimp, Litopenaeus vannamei (actually a prawn)
• 
  Spotted cleaner shrimp, Periclimenes yucatanicus
• 
  California spiny lobster, Panulirus interruptus
• 
  Blue crab, Callinectes sapidus
• 
  Lyreidus tridentatus, another crab