The Ixodidae are the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

of hard ticks or scale ticks, one of the three families of

tick Ticks (order Ixodida) are parasitic arachnids that 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 ...

s, consisting of over 700 species. They are known as 'hard ticks' because they have a

scutum The ''scutum'' (; plural ''scuta'') was a type of shield used among Italic peoples in antiquity, most notably by the army of ancient Rome starting about the fourth century BC. The Romans adopted it when they switched from the military formatio ...

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 A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury. Diseases are often known to be medical conditions that a ...

Description

They are distinguished from the Argasidae by the presence of a scutum. In both the

nymph A nymph ( grc, νύμφη, nýmphē, el, script=Latn, nímfi, label=Modern Greek; , ) in ancient Greek folklore is a minor female nature deity. Different from Greek goddesses, nymphs are generally regarded as personifications of nature, are ...

and the adult, a prominent

gnathosoma The gnathosoma (from Greek , ' = "jaw" and , ' = "body") is the part of the body of the Acari ( mites and ticks) comprising the mouth and feeding parts. These are the hypostome, the chelicerae and the pedipalps. It is also called the capitulum (h ...

(or capitulum,

mouth In animal anatomy, the mouth, also known as the oral cavity, or in Latin cavum oris, is the opening through which many animals take in food and issue vocal sounds. It is also the cavity lying at the upper end of the alimentary canal, bounded on ...

and feeding parts) projects forward from the animal's body; in the Argasidae, conversely, the gnathosoma is concealed beneath the body. They differ, too, in their

lifecycle Life cycle, life-cycle, or lifecycle may refer to: Science and academia *Biological life cycle, the sequence of life stages that an organism undergoes from birth to reproduction ending with the production of the offspring *Life-cycle hypothesis, ...

; Ixodidae that attach to a host bite painlessly and are generally unnoticed, and they remain in place until they engorge and are ready to change their skin; this process may take days or weeks. Some species drop off the host to

moult In biology, moulting (British English), or molting (American English), also known as sloughing, shedding, or in many invertebrates, ecdysis, is the manner in which an animal routinely casts off a part of its body (often, but not always, an outer ...

in a safe place, whereas others remain on the same host and only drop off once they are ready to lay their eggs.

Classification

There are 702 species in 17 genera. The family contains these genera: * '' Africaniella'' – two species * '' Amblyomma'' – 130 species (includes some of ''Aponomma'') * '' Anomalohimalaya'' – three species * '' Archaeocroton'' – one species * '' Bothriocroton'' – seven species * '' Cosmiomma'' – one species * '' Cornupalpatum'' – one species * '' Compluriscutula'' – one species * '' Dermacentor'' – 34 species (includes ''Anocentor'') * '' Haemaphysalis'' – 166 species * '' Hyalomma'' – 27 species * '' Ixodes'' – 246 species * '' Margaropus'' – three species * '' Nosomma'' – two species * '' Rhipicentor'' – two species * '' Rhipicephalus'' – 82 species (includes ''Boophilus'') * '' Robertsicus'' – one species

Fossil genera

* †'' Compluriscutula'' Poinar and Buckley 2008

Burmese amber Burmese amber, also known as Burmite or Kachin amber, is amber from the Hukawng Valley in northern Myanmar. The amber is dated to around 100 million years ago, during the latest Albian to earliest Cenomanian ages of the mid-Cretaceous period. The ...

, Myanmar,

Cenomanian The Cenomanian is, in the ICS' geological timescale, the oldest or earliest age of the Late Cretaceous Epoch or the lowest stage of the Upper Cretaceous Series. An age is a unit of geochronology; it is a unit of time; the stage is a unit in ...

* †'' Cornupalpatum'' Poinar and Brown 2003 Burmese amber, Myanmar, Cenomanian

Medical importance

Many hard ticks are of considerable medical importance, acting as vectors of diseases caused by bacteria, protozoa, and viruses, such as ''

Rickettsia ''Rickettsia'' is a genus of nonmotile, gram-negative, nonspore-forming, highly pleomorphic bacteria that may occur in the forms of cocci (0.1 μm in diameter), bacilli (1–4 μm long), or threads (up to about 10 μm long). The term "ricke ...

'' and '' Borrelia''. The saliva of female ticks is toxic, causing ascending paralysis in animals and people, known as tick paralysis. Tick species that are commonly associated with tick paralysis are '' Dermacentor andersoni, Dermacentor occidentalis, Dermacentor variabilis,'' and '' Ixodes holocyclus''. Other tick-borne diseases include

Lyme disease Lyme disease, also known as Lyme borreliosis, is a vector-borne disease caused by the '' Borrelia'' bacterium, which is spread by ticks in the genus '' Ixodes''. The most common sign of infection is an expanding red rash, known as erythema ...

babesiosis Babesiosis or piroplasmosis is a malaria-like parasitic disease caused by infection with a eukaryotic parasite in the order Piroplasmida, typically a ''Babesia'' or ''Theileria'', in the phylum Apicomplexa. Human babesiosis transmission via tic ...

, ehrlichiosis, Rocky Mountain spotted fever,

anaplasmosis Anaplasmosis is a tick-borne disease affecting ruminants, dogs, and horses, and is caused by ''Anaplasma'' bacteria. Anaplasmosis is an infectious but not contagious disease. Anaplasmosis can be transmitted through mechanical and biological vector ...

, Southern tick-associated rash illness,

tick-borne relapsing fever Relapsing fever is a vector-borne disease caused by infection with certain bacteria in the genus ''Borrelia'', which is transmitted through the bites of lice or soft-bodied ticks (genus ''Ornithodoros''). Signs and symptoms Most people who are ...

, tularemia, Colorado tick fever, Powassan encephalitis, and Q fever.

References

External links