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 by ...

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 formati ...

or hard shield, which the other major family of ticks, the 'soft ticks' (

Argasidae 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 ...

), lack. They are

ectoparasites Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson ha ...

of a wide range of host species, and some are

vector Vector most often refers to: *Euclidean vector, a quantity with a magnitude and a direction *Vector (epidemiology), an agent that carries and transmits an infectious pathogen into another living organism Vector may also refer to: Mathematic ...

s 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 pedipalp Pedipalps (commonly shortened to p ...

(or capitulum, mouth 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; 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 ''Amblyomma'' is a genus of hard ticks. Some are disease vectors, for example the Rocky Mountain spotted fever in Brazil or ehrlichiosis in the United States. This genus is the third largest in the family Ixodidae, with its species primarily o ...

'' – 130 species (includes some of ''Aponomma'') * '' Anomalohimalaya'' – three species * '' Archaeocroton'' – one species * '' Bothriocroton'' – seven species * ''

Cosmiomma ''Cosmiomma'' is a genus of ticks first discovered by Paul Schulze in 1919. Paul Schulze. 1919. Bestimmungstabelle für das Zeckengenus ''Hyalomma'', Koch. ''Sitzungsberichte der Gesellschaft Naturforschender Freunde zu Berlin'', 5:189–196, ht ...

'' – one species * '' Cornupalpatum'' – one species * '' Compluriscutula'' – one species * ''

Dermacentor ''Dermacentor'' is a genus of ticks in the family Ixodidae, the hard ticks. The genus has a cosmopolitan distribution, with native species on all continents except Australia. Most occur in the Nearctic realm. Hosts of ''Dermacentor'' ticks incl ...

'' – 34 species (includes ''Anocentor'') * ''

Haemaphysalis ''Haemaphysalis'' is a genus of ticks, containing these species: *'' Haemaphysalis aborensis'' Warburton, 1913 *'' Haemaphysalis aciculifer'' Warburton, 1913 *'' Haemaphysalis aculeata'' Lavarra, 1904 *'' Haemaphysalis adleri'' Feldman-Muhsam, 1 ...

'' – 166 species * ''

Hyalomma ''Hyalomma'' is a genus of hard-bodied ticks common in Asia, Europe, and North Africa. They are also found in Southern Africa. The name is derived from Greek: hyalos (ὕαλος) crystal, glass; and omma (oμμα) eye. The genus is believed to ...

'' – 27 species * ''

Ixodes ''Ixodes'' is a genus of hard-bodied ticks (family Ixodidae). It includes important disease vectors of animals and humans ( tick-borne disease), and some species (notably '' Ixodes holocyclus'') inject toxins that can cause paralysis. Som ...

'' – 246 species * ''

Margaropus ''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 na ...

'' – three species * '' Nosomma'' – two species * '' Rhipicentor'' – two species * ''

Rhipicephalus ''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.Olwoch, J. M., et al. (2007)Climate change and the genus ''Rhipicephalus'' (Acari: Ixodidae) in ...

'' – 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 * †'' 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 ''Borrelia'' is a genus of bacteria of the spirochete phylum. Several species cause Lyme disease, also called Lyme borreliosis, a zoonotic, vector-borne disease transmitted by ticks. Other species of ''Borrelia'' cause relapsing fever, and are t ...

''. 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 andersoni'', commonly known as the Rocky Mountain wood tick, is a hard tick, or member of the Ixodidae family, with three life stages including larvae, nymph, and finally adult, or, more entomologically, imago. This tick is genera ...

, Dermacentor occidentalis,

Dermacentor variabilis ''Dermacentor variabilis'', also known as the American dog tick or wood tick, is a species of tick that is known to carry bacteria responsible for several diseases in humans, including Rocky Mountain spotted fever and tularemia (''Francisella tul ...

,'' and ''

Ixodes holocyclus ''Ixodes holocyclus'', commonly known as the Australian paralysis tick, is one of about 75 species in the Australian tick fauna and is considered the most medically important. It can cause paralysis by injecting neurotoxins into its host. It is u ...

''. 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 migran ...

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 ...

ehrlichiosis Ehrlichiosis is a tick-borne bacterial infection, caused by bacteria of the family Anaplasmataceae, genera '' Ehrlichia'' and ''Anaplasma''. These obligate intracellular bacteria infect and kill white blood cells. The average reported annual in ...

Rocky Mountain spotted fever Rocky Mountain spotted fever (RMSF) is a bacterial disease spread by ticks. It typically begins with a fever and headache, which is followed a few days later with the development of a rash. The rash is generally made up of small spots of bleedin ...

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 Southern tick-associated rash illness (STARI) is an emerging infectious disease related to Lyme disease that occurs in southeastern and south-central United States. It is spread by tick bites and it was hypothesized that the illness was caused by ...

, tick-borne relapsing fever,

tularemia Tularemia, also known as rabbit fever, is an infectious disease caused by the bacterium ''Francisella tularensis''. Symptoms may include fever, skin ulcers, and enlarged lymph nodes. Occasionally, a form that results in pneumonia or a throat infe ...

Colorado tick fever Colorado tick fever (CTF) is a viral infection (Coltivirus) transmitted from the bite of an infected Rocky Mountain wood tick ('' Dermacentor andersoni''). It should not be confused with the bacterial tick-borne infection, Rocky Mountain spotted f ...

, Powassan encephalitis, and

Q fever Q fever or query fever is a disease caused by infection with ''Coxiella burnetii'', a bacterium that affects humans and other animals. This organism is uncommon, but may be found in cattle, sheep, goats, and other domestic mammals, including ...

References

External links