Crustacea
They have two pairs of sensitive antennae, one pair of
mandibles, and two pairs of maxillae. Crustaceans lack a
backbone and arthropods (which also includes the
insects). A Class of animals that have
a firm exoskeleton, jointed legs, and a segmented body
that is equal.
Most crustaceans live in water, but some live on land.
Crustaceans are the most abundant animals in the oceans,
but some crustaceans live on fresh water. There are
about 30,500 known species of crustaceans around the
world.
Characteristics of
Crustaceans:
-
Have a hard exoskeleton composed of
calcium and no interior skeleton.
-
Two eyes, two pairs of antennae, and
three pairs of mouthparts.
-
A pair of green glands excretes wastes
near the base of antennae.
-
The tail is fan-shaped, and ends in
uropods and a telson.
-
The circulatory system is open; there
is no heart and the "blood" is pumped by vessels into
sinuses, and does not flow in a closed loop.
-
The nervous system consists of a
primitive ventral nerve cord and ganglia system
(similar to those of an earthworm).
Class:
Kingdom Animalia, Phylum
Arthropoda, Subphylum Crustacea, Classes:
-
Class Cephalocarida (primitive,
shrimp-like, discovered in 1955) - 9 species
-
Class Branchiopoda (with flattened
gill-carrying appendages)
-
Class Malacostraca
-
Class Maxillopoda (ostracods,
copepods, barnacles)
-
Class Remipedia (primitive crustaceans
discovered in submerged caves by Jill Yager in 1980)
