Page 174 - Ultimate Visual Dictionary (DK)

ANIMALS
Crustaceans

1st swimmeret
THE SUBPHYLUM CRUSTACEA is one of the largest groups (1st pleopod)
in the phylum Arthropoda. The subphylum is divided
into several classes, the most important of which
are Malacostraca and Cirripedia. The class
Malacostraca includes crayfish, crabs,
lobsters, and shrimps. Typical features of
malacostracans include a body divided
2nd swimmeret
into two sections (a combined head (2nd pleopod)
and thorax called a cephalothorax, 3rd swimmeret (3rd pleopod)
and an abdomen); an exoskeleton 4th swimmeret (4th pleopod)
(external skeleton) with a large 5th swimmeret (5th pleopod)
plate (carapace) covering the
Telson Abdomen
cephalothorax; stalked,
compound eyes; and two
pairs of antennae. The class
Cirripedia includes barnacles,
which, unlike other
crustaceans, spend their
adult lives attached to a Endopod
Uropod
surface, such as a rock. Other Exopod
Abdominal
characteristics of cirripedes segment
include an exoskeleton of
3rd leg
overlapping calcareous plates;
(3rd pereopod)
a body consisting almost entirely
of thorax (the abdomen and head
are minute); and six pairs of thoracic
appendages (cirri) used for filter feeding.
5th leg (5th 2nd leg (2nd
EXTERNAL FEATURES Propodus pereopod) pereopod)
OF A CRAB
Dactylus 4th leg (4th
Carpus
pereopod)
Compound eye
Antenna
EXTERNAL FEATURES OF A SHRIMP
Cheliped (chela;
claw; 1st leg; Cephalothorax
1st pereopod) Compound eye
Abdomen
Carapace (shell)

Merus Antenna
Leg Swimmeret
Abdomen 2nd leg (pereopod) (pleopod)
(2nd pereopod)
Exopod
Uropod
Endopod
5th leg (5th pereopod) 3rd leg (3rd pereopod)
Telson
4th leg (4th pereopod)
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