Tick is the common name for the small arachnids in superfamily Ixodoidea that, along with other mites, constitute the Acarina. Ticks are ectoparasites (external parasites), living by hematophagy on the blood of mammals, birds, and occasionally reptiles and amphibians. Ticks are vectors of a number of diseases, including Lyme disease, Q fever, Colorado tick fever, tularemia, tick-borne relapsing fever, babesiosis, ehrlichiosis and Tick-borne meningoencephalitis, as well as anaplasmosis in cattle and canine jaundice.
Young ticks have six legs, and mature ticks have eight legs. They vary in size and appearance depending on the species.
Habitats and behaviors
Ticks are blood-feeding parasites that are often found in tall grass and shrubs where they will wait to attach to a passing host. A tick will attach itself to its host by inserting its chelicerae (cutting mandibles) and hypostome (feeding tube) into the skin. The hypostome is covered with recurved teeth and serves as an anchor.
Physical contact is the only method of transportation for ticks. Ticks do not jump or fly, although they may drop from their perch and fall onto a host. Some species stalk the host from ground level, emerging from cracks or crevices located in the woods or even inside a home or kennel, where infestations of "seed ticks" (the six-legged stage of newborn ticks) can attack in numbers up to 3,000 at a time. Weak or elderly dogs and puppies are particularly endangered and can die from anemia from a sudden influx of seed ticks. Seed ticks also attack horses, cattle, moose, lions and other mammals, causing anemia, various diseases, paralysis and even death. Such infestations can be difficult to detect until thousands have attached themselves to an animal and eradication can be difficult.
Mature ticks are easier to see and can be removed with care. Frequent grooming and chemicals for control may control the spread of seed ticks and adults.
Changes in temperature and day length are some of the factors signalling a tick to seek a host. Ticks can detect heat emitted or carbon dioxide respired from a nearby host. They will generally drop off the animal when full, but this may take several days. In some cases ticks will live for some time on the blood of an animal. Ticks are more active outdoors in warm weather, but can attack a host at any time.
Ticks can be found in most wooded or forested regions throughout the world. They are especially common in areas where there are deer trails or human tracks. Ticks are especially abundant near water, where warm-blooded animals come to drink, and in meadows wherever shrubs and brush provide woody surfaces and cover.
Engorged deer tick attached to back of toddler`s head. Adult thumb shown for scale.