Ticks are parasitic arachnids of the order Ixodida. They are part of the mite superorder Parasitiformes. Adult ticks are approximately 3 to 5 mm in length depending on age, sex, species, and "fullness". Ticks are external parasites, living by feeding on the blood of mammals, birds, and sometimes reptiles and amphibians. The timing of the origin of ticks is uncertain, though the oldest known tick fossils are from the Cretaceous period, around 100 million years old. Ticks are widely distributed around the world, especially in warm, humid climates.
The Ixodidae are the family of hard ticks or scale ticks, one of the three families of ticks, consisting of over 700 species. They are known as 'hard ticks' because they have a scutum or hard shield, which the other major family of ticks, the 'soft ticks' (Argasidae), lack. They are ectoparasites of a wide range of host species, and some are vectors of pathogens that can cause human disease.
The Argasidae are the family of soft ticks, one of the three families of ticks. The family contains 193 species, although the composition of the genera is less certain, and more study is needed before the genera can become stable. The currently accepted genera are Antricola, Argas, Nothoaspis, Ornithodoros, and Otobius. The Argasidae are very common in South Asia, along with 96 other species of ticks, making South Asia the region with the highest biodiversity of ticks worldwide. Soft ticks are resistant to desiccation and can live for several years in arid conditions.
Parasitiformes are a superorder of Arachnids, constituting one of the two major groups of mites, alongside Acariformes. Parasitiformes has, at times, been classified at the rank of order or suborder.
George Henry Falkiner Nuttall FRS was an American-British bacteriologist who contributed much to the knowledge of parasites and of insect carriers of diseases. He made significant innovative discoveries in immunology, about life under aseptic conditions, in blood chemistry, and about diseases transmitted by arthropods, especially ticks. He carried out investigations into the distribution of Anopheline mosquitoes in England in relation to the previous prevalence of malaria there. With William Welch he identified the organism responsible for causing gas gangrene.
Ixodes is a genus of hard-bodied ticks. It includes important disease vectors of animals and humans, and some species inject toxins that can cause paralysis. Some ticks in this genus may transmit the pathogenic bacterium Borrelia burgdorferi responsible for causing Lyme disease. Additional organisms that may be transmitted by Ixodes are parasites from the genus Babesia, which cause babesiosis, and bacteria from the related genus Anaplasma, which cause anaplasmosis.
The hypostome is a calcified harpoon-like structure near the mouth area of certain parasitic arthropods including ticks, that allows them to anchor themselves firmly in place on a host vertebrate while sucking blood. The hypostome being present in almost all tick families suggests that hematophagy is the ancestral condition, as is the fact that life stages that do not feed on blood lack the organ.
Rhipicephalus is a genus of ticks in the family Ixodidae, the hard ticks, consisting of about 74 or 75 species. Most are native to tropical Africa.
Ornithodoros is a genus in the soft-bodied tick family, Argasidae.
Haemaphysalis is a genus of ticks, containing these species:
Jane Brotherton Walker was a Kenyan-South African scholar in the field of tick taxonomy, particularly in Africa.
Makram Nasri Kaiser (1930–1996) was a medical and veterinary acarologist who was the world's leading authority on ticks of the genus Hyalomma.
Gerald Augustus Harold Bedford was a British entomologist of the 20th century who specialised in ticks from South Africa.
Haemaphysalis hystricis, the East Asian mountain haemaphysalid, is a hard-bodied tick of the genus Haemaphysalis. It is found in India, Sri Lanka, Vietnam, Myanmar, China, Japan, India, Indonesia, Laos, Taiwan and Thailand. It is an obligate ectoparasite of mammals. It is a potential vector of Kyasanur Forest disease virus, Coxiella sp., Ehrlichia sp., and Rickettsia japonica. In 2007, an unknown trypanosoma species known as Trypanosoma KG1 isolate was isolated from naturally infected H. hystricis ticks.
Dermacentor reticulatus, also known as the ornate cow tick, ornate dog tick, meadow tick, and marsh tick, is a species of tick from the family Ixodidae. It is the type species for the genus Dermacentor. D. reticulatus is an ornate tick. The female varies in size from 3.8–4.2 mm (unfed) to 10 mm when engorged after feeding. The unfed male is 4.2–4.8 mm long. D. reticulatus is found in Europe and Western Asia, generally in wooded areas.
The zebra tick or yellow back tick is a species of hard tick. It is common in the Horn of Africa, with a habitat of the Rift Valley and eastward. It feeds upon a wide variety of species, including livestock, wild mammals, and humans, and can be a vector for various pathogens. The adult male has a distinctive black and ivory ornamentation on its scutum.
Maria Vladimirovna Pospelova-Shtrom (1902–1991) was a 20th century parasitologist best known for her work delineating the biology and public health importance of ticks in western Asia and eastern Europe, contributing to the reduction of the incidence of tick-borne diseases, especially tick-borne relapsing fever.
Margaropus is a genus of ticks, characterized as inornate, having eyes, lacking festoons, and with the legs of the male increasing in size from pair I to IV with the segments enlarged, giving them a beaded appearance, from which the genus name was taken, margaritopus signifying beady-legged; the species name memorialized naturalist and entomologist Wilhelm von Winthem.
Margaropus reidi, the Sudanese beady-legged tick, is an ixodid tick that is parasitic on the Northern giraffe It is one of only three species in the genus Margaropus. The type specimens were collected in Liednhom on the south bank of the Jur River, and at Guar, in the Gual-Nyang Forest, Bahr el Ghazal, South Sudan.
