Relationships of living and extinct tick families, after Chitimia-Dobler et al. Nuttalliella namaqua is found in southern Africa ranging from Tanzania to Namibia and South Africa. It comprises a single species, Nuttalliella namaqua, and as such is a monotypic taxon. The third living family is Nuttalliellidae, named for the bacteriologist George Nuttall. The majority of tick species belong to the two families: Ixodidae (hard ticks) and Argasidae (soft ticks). Ticks belong to three different families. A phylogenetic analysis suggests that the last common ancestor of all living ticks likely lived around 195 million years ago in the Southern Hemisphere, in what was then Gondwana. The younger Baltic and Dominican ambers have also yielded examples that can be placed in living genera. An undescribed juvenile tick is known from late Albian Spanish amber, dating to 105 million years ago. The oldest discovered tick fossils are an argasid bird tick from Late Cretaceous ( Turonian ~94-90 million years ago) aged New Jersey amber, and various ticks found in Burmese amber, including Khimaira and Deinocroton, which do not belong to any living family of tick, and members of the living ixodid genera Amblyomma, Ixodes, Haemaphysalis, Bothriocroton and Archaeocroton dating the earliest Cenomanian stage of the Late Cretaceous, around 99 million years ago. ![]() Relationships among members of the Parasitiformes, after Klompen, 2010: įossilized ticks have been discovered from the end of the Early Cretaceous onwards, most commonly in amber. Within the Parasitiformes, ticks are most closely related to the Holothyrida, a small group of free living scavengers with 32 described species confined to the landmasses that formed the supercontinent Gondwana. Whether the two groups are more closely related to each other than to other arachnids is uncertain, and studies often recover them as not closely related. Ticks belong to the Parasitiformes, a distinctive group of mites that are separate from the main group of mites, the Acariformes. Because of their hematophagous (blood-ingesting) diets, ticks act as vectors of many serious diseases that affect humans and other animals.īiology Taxonomy and phylogeny Fossilized tick in Dominican amber Argasid ticks have up to seven nymphal stages ( instars), each one requiring blood ingestion, and as such, Argasid ticks undergo a multihost life cycle. Ticks belonging to the Ixodidae family undergo either a one-host, two-host, or three-host life cycle. Ticks have four stages to their life cycle, namely egg, larva, nymph, and adult. Ticks locate potential hosts by sensing odor, body heat, moisture, and/or vibrations in the environment. In addition to having a hard shield on their dorsal surfaces, known as the scutum, hard ticks have a beak-like structure at the front containing the mouthparts, whereas soft ticks have their mouthparts on the underside of their bodies. Their cephalothorax and abdomen are completely fused. Adults have ovoid/pear-shaped bodies (idiosomas) which become engorged with blood when they feed, and eight legs. ![]() Nuttalliella, a genus of tick from southern Africa, is the only member of the family Nuttalliellidae, and represents the most primitive living lineage of ticks. Ticks belong to two major families, the Ixodidae or hard ticks, and the Argasidae, or soft ticks. Ticks are widely distributed around the world, especially in warm, humid climates. 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 external parasites, living by feeding on the blood of mammals, birds, and sometimes reptiles and amphibians. Adult ticks are approximately 3 to 5 mm in length depending on age, sex, species, and "fullness". Ticks (order Ixodida) are parasitic arachnids that are part of the mite superorder Parasitiformes.
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