Tick

Tick is a common name for a group of external bloodsucking parasitic arthropods of vertebrates (mainly of terrestrial mammals and birds). They belong to class ARACHNIDA, subclass Acari, order Parasitiformes, suborder Ixodida. About 800 species are known worldwide; the 40 species known in Canada are found in all areas south of the TREELINE.

Description

Among the largest of Acari, ticks are 1-5 mm long when unfed, up to 30 mm when fully gorged. Ticks are distinguished by their highly modified mouthparts, used in piercing and attaching to hosts, and by a specialized sensory structure (Haller's organ) near the tip of each first leg, used in locating hosts.

Relationship with Humans

In Canada, ticks are important pests of humans, livestock and game animals. Members of genus Dermacentor sometimes cause serious loss of cattle from tick paralysis, a condition the ticks cause by feeding on the cattle, not by transmitting disease.

Ticks harbour and spread an unusual variety of disease-causing pathogens to their hosts, including protozoa, rickettsia, bacteria and viruses. In Canada they may transmit Colorado tick, rickettsial Q and Rocky Mountain spotted fevers, bacterial tularemia, spirochaete Lyme disease and viral Powassan encephalitis. Although the disease strains in Canada are usually not of serious medical or veterinary importance, the recent spread of Lyme disease has assumed increasing medical attention and considerable public concern.

Author EVERT E. LINDQUIST

Links to Other Sites
Canadian Biodiversity Website
A great information source for all budding biologists. Learn about biodiversity theory, natural history, and conservation issues. From McGill’s Redpath Museum.

AboutKidsHealth
Check out the colourful AboutKidsHealth website for online articles on hundreds of childhood ailments, medications, behavioural issues, and medical procedures. Also offers an animated "How the Body Works" feature, and much more. From the Hospital for Sick Children (SickKids) in Toronto.

The Canadian National Collection of Insects, Arachnids and Nematodes
This website provides information about the scope and contents of the Canadian National Collection of Insects, Arachnids and Nematodes. Check the “Index” link for illustrated descriptions of various taxonomic groups.