Arthropods are part of the largest and most diverse phylum in the animal kingdom. The phylum which I am speaking of is called Arthropoda, which is Latin for "jointed feet." Arthropods are arranged of more than one million invertebrate species within four subphyla. The four subphyla consist of five classes of Uniramia including insects, three classes of Chelicerata including horseshoe crabs and arachnids, Trilobita (which are extinct), and Crustacea. When you break down an arthropod you will find that every single one of them are bilaterally symmetrical and have a segmented body that is protected by an exterior shell which contains chitin. Chitin serves two purposes fo the arthropod. It first serves as armor to protect the arthropod from predators, weather, and whatever else it may encounter. The second purpose it serves is to be a surface for the muscles to attach to. Each body segment the arthropod has bears a pair of jointed arms or legs. Insects are arthropods with six legs and they are the only arthropods that are able to fly. Arachnids are also arthropods. The most well known arachnids are probably spiders, but scorpions, mites, and ticks are also Arachnids. As you can guess, Arachnids are arthropods with eight legs. Most Arachnids live on land, but there are few who live in freshwater. Another arthropod species is crustaceans. Crustaceans have ten or more legs and most of them are aquatic. The most widely known crustaceans consist of shrimp, lobsters, and crabs. There are a few crustaceans, like woodlice, live on land rather than in the water.
Being the largest phylum in the animal kingdom, arthropods are very critical to the animal world. An example of this can be seen by their contribution to the food chain. As we know food is a very major source of energy and without energy it is very hard to carry on your necessary activities. All animal groups including arthropods feed on arthropods. Birds, fish, reptiles, plants, and even humans feed on arthropods....
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