Phylum Arthropoda - Class Crustracea Crabs & Shrimps
This is the largest animal phylum, primarily because it includes the insects. There are very few marine insects, however, and the great minority of the marine arthropods belong to the Class Crustacea. The crustaceans include the barnacles, copepods, amphipods, isopods, crabs, shrimp and lobsters. Barnacles are among the more ubiquitous invertebrates in the sea; they are found on jetties, pilings, boat hulls, shells, crabs, turtles, whales, driftwood and Sargassum. Copepods are one of the most important invertebrate taxa in the sea, forming a major food link between the microscopic plant life called phytoplankton and small fish. Isopods and amphipods may be found in damp crevices, among the seaweeds of the jetties, in edible beach drift and in sa;t marches. Various crabs may be found swimming in the bays, hiding among the boulders on the jetties, burrowing in the surf zone or living in old tin cans. Likewise, various species of shrimp live on the muddy bay bottom, crawl about on the jetty boulders, cling to submerged grasses or burrow into mud flat.
The phylum Arthropoda is made up of many classes. The following are some of the more important marine classes:
1) Class: Merostomata--horeshoe crabs
(2) Class: Pycnogonida--sea spiders
(3) Class: Crustacea--shrimp, crabs, etc
The following are some major subclasses of the class Crustacea:
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