Body Anatomy
Crustaceans are the only arthropods that have two pairs of appendages on their head that serve as feelers. Each other body segment is generally a pair and at least some are branched, Most crustaceans have 16-20 segments, which are fused to any number of tagmata. The exoskeleton of aquatic crustaceans contain large amounts of calcium making them very hard. larger crustaceans respire with gills. Exist in a range of sizes, but are mostly small and respire via thin areas of the exoskeleton. The small crustaceans often fall into the plankton variety and make up a hefty percentage. Some crustaceans are even sessile and have resorted to covering themselves in calcium carbonate and using their six feet, cirri, to feed.
External structures of the crayfish include; The abdomen, cephelothorax, which is the fused head and thorax. Fusing the head and the thorax is a single tough covering called the carapace. The abdomen of Crayfish is divided into seven segments and is ended with the seventh segment called the telson. The telson is a strong fin like structure used for movement. The anterior end or the head of the crayfish have the antennae and antennules. They use these as feelers and have many uses as auxiliary sensory organs.
External structures of the crayfish include; The abdomen, cephelothorax, which is the fused head and thorax. Fusing the head and the thorax is a single tough covering called the carapace. The abdomen of Crayfish is divided into seven segments and is ended with the seventh segment called the telson. The telson is a strong fin like structure used for movement. The anterior end or the head of the crayfish have the antennae and antennules. They use these as feelers and have many uses as auxiliary sensory organs.
Habitat, Diet, Life Cycle
Crustaceans are the main type of arthropods to be aquatic. Other subphyla are mostly terrestrial, with exceptions, of course. Most crustaceans are also motile, moving independently. The exception being crustacean lice and barnacles. Crustaceans can have both spesific genders and also may be hermaphrodites. they molt like all other arthropods.
Examples
Crabs, lobsters, shrimp, krill, barnacles, copepods, brine shrimp.