All arthropods have several pairs of jointed legs and a hard outside covering or exoskeleton.
Ticks differ from insects in not having wings or antennae and in having four rather than three pairs of legs. About 800 types, or species, of ticks are known from throughout the world. All species are parasites in that they must locate, attach to and feed from an animal for their growth and reproduction. It is this life style, the feeding from animals, that makes ticks of importance to human health. The tick most commonly observed in New York State is the American Dog Tick.