Phylum Arthropoda, Subphylum Crustacea

• The majority of marine arthropods are crustaceans (subphylum Crustacea)

• Crustaceans are distinguished from other Arthropods by their possession of a pair of biramous (two-parted) limbs, and by a nauplius larval stage– Includes barnacles, shrimp,

krill, crabs, lobsters, and copepods

http://www.earthlife.net/inverts/crustacea.html

Phylum Arthropoda, Subphylum Crustacea

• Crustaceans are specialized for life in the water– Most possess gills to obtain oxygen– Chitinous exoskeleton reinforced with CaCO3

– Two pairs of antennae

Barnacles are crustaceans!

The wonderful world of crustaceans!

Amphipods have a curved body that is flattened sideways

Isopods are dorsoventrally flattened

Shrimps, lobsters and crabs are decapods; all have ten legs made up of 5 pairs of appendages

12-5

Molting

• Arthropods must molt, or shed, their exoskeleton as they grow

• Most arthropods are small because the rigid exoskeleton puts limitations on their size

serc.si.eduhttp://movingspaceproductions.com/view.php?video=Daz8nkh-pWM&feature=youtube_gdata_player&title=Molting+horseshoe+crab

serc.si.eduafcd.gov.hk

Other Marine Arthropods

• Other than crustaceans, there are relatively few marine Arthropods

• Horseshoe crabs are not crustaceans, and belong to subphylum Chelicerata– Largely extinct; only five living species– Horseshoe-shaped carapace* that encloses a body

with six pairs of legs*shield-like structure that covers anterior portion of

Arthropods