This article is about the parasitic arachnid. For the fictional superhero, see The Tick. For the v-shaped mark denoting that something has been noted, completed, is correct, etc., see check. A clock tick is, especially in computing, the smallest unit of time of a system. See also: Jiffy.

Ticks
Scientific classification
Kingdom: Animalia Phylum: Arthropoda Class: Arachnida Order: Acarina
Families
Ixodidae - Hard ticks Argasidae - Soft ticks

Tick is the common name for the small wingless arachnids that, along with mites, comprise the order Acarina. Ticks are external parasites, living off the blood of mammals, birds, and occasionally reptiles and amphibians.

The major families of tick include the Ixodidae or hard ticks, which have thick outer shells made of chitin, and Argasidae or soft ticks, which have a membraneous outer surface. Soft ticks typically live in crevices and emerge briefly to feed, while hard ticks will embed themselves beneath the skin of a host for long periods of time.

Adult deer tick.

Ticks can transmit human diseases such as relapsing fever, Lyme disease, Rocky Mountain spotted fever, tularemia, equine encephalitis and several forms of ehrlichiosis. Additionally, they are responsible for transmitting livestock diseases, including babesiosis and anaplasmosis. Generally, tick-borne diseases correspond to a specific tick-host combination, and are limited in their geographical extent.

Ticks are often found in tall grass, where they will rest themselves at the tip of a blade so as to attach themselves to a passing animal or human. They will generally drop off of the animal when full, but this may take several days. Ticks contain a structure in their mouth area that allows them to anchor themselves firmly in place while sucking blood. Pulling a tick out forcefully out from under the skin often leaves the head behind. See also Tick removal.

Dermacentor variabilis, the American dog tick, is perhaps the most well-known of the North American hard ticks. Ixodes dammini, the deer tick, is common to the eastern part of North America and is known for spreading Lyme disease. A close cousin of I. dammini, Ixodes pacificus lives in the western part of the continent and is responsible for spreading Lyme disease and the more deadly Rocky Mountain spotted fever. I. pacificus tends to prefer livestock as its adult host.

Life cycle

Each species of tick requires three different hosts to complete its life cycle. Generally, the larval stage feeds on small reptiles, birds, or mammals, and the adult will parasitize larger mammals.

External links

• Comparison of tick removal methods (http://www.biosci.ohio-state.edu/~acarolog/tickgone.htm)