1)an invertebrate animal of the large phylum Arthropoda, such as an insect, spider, or crustacean.ny invertebrate of the phylum Arthropoda, having a segmented body, jointed limbs, and usually a chitinous shell that undergoes moltings, including the insects, spiders and other arachnids, crustaceans, and myriapodsThey are everywhere and are the largest animal phylum. About 85% of all known animals in the world are part of this classThey are spiders, insects, centipedes, mites, ticks, lobsters, crabs, shrimp, crayfish, krill, barnacles, scorpions and many, many others.
2)A complex rigid outside covering that gives the muscles something to pull against. Unlike a simple shell such as those of mollusks, an exoskeleton has many flexible joints, allowing a wide range of movement. So arthropods are very good as little animals, but have serious size limitations, which they make up for in numbers. Wherever you are, you are probably outnumbered by the arthropods in your immediate vicinity by hundreds, maybe thousands, to one.
3)CRUSTACEA : members display much variation in the tagmata and the appendages 30,000 species of Crustacea. One of the latter is the Isopoda.
ARACHNIDA : spiders, ticks, mites, scorpion are examples. Chelicerates have six pairs of appendages. First two pairs being mouthparts and the following four pairs being legs.
CHILOPODA : usually found in somewhat protected places like n leaf litter, in the soil, under bark, or in rotten logs. The larger centipedes can bite humans. But the bite is not serious and is no more painful that the sting of a bee or wasp.
DIPLOPODA : he first three trunk segments usually not cylindrical. Few attack living plants and are sometimes pests.
INSECTA : 1,000,000 species have been described and named
4) Most people will likely encounter only two orders, the Orders Decapoda and Isopoda. order decapoda: Lobsters, crayfish, crabs, shrimp! order Isopoda:Sowbugs, pillbugs, roly-polys. first pair of antennae is greatly reduced , seldom noticed. There are a few freshwater forms of isopoda. Those that can not form a ball are the sowbugs.
5) CRUSTACEA Name ->Tadpole Shrimp Class:Branchiopoda Order:Notostraca Family:Triopsidae Genus:Triops Species:Triops longicaudatus....Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles.