The Crustaceans breathe by means of gills, and their bodies consist of rings. They have two pairs of feelers and two pairs of jaws, to which are mostly joined one or more pairs of jaw feet. All the remaining rings of the body may have a pair of limbs each. The head bears two pairs of feelers. Crustaceans commonly hatch out as free-swimming larvæ, like the adult in form.

This large class of jointed-limbed animals includes lobsters, prawns, shrimps, crabs, and other familiar forms, the great bulk of which are aquatic, though the wood-lice have become adapted to a life on land.


1. Common Lobster. 2. Thornback Crab. 3. Land Crab. 4. Hermit Crab.
5. Barnacle. 6. Scorpion. 7. Antarctic Trilobite.