The cephalothorax , also called prosoma in some groups, is a tagma of various arthropods , comprising the head and the thorax fused together, as distinct from the abdomen behind. (The terms prosoma and opisthosoma are equivalent to cephalothorax and abdomen in some groups. The terms prosoma and opisthosoma may be preferred by some researchers in cases such as arachnids, where there is neither fossil nor embryonic evidence animals in this class have ever had separate heads and thoraxes, and where the opisthosoma contains organs atypical of a true abdomen , such as a heart and respiratory organs. ) The word cephalothorax is derived from the Greek words for head ( κεφαλή , kephalé ) and thorax ( θώραξ , thórax ). This fusion of the head and thorax is seen in chelicerates and crustaceans ; in other groups, such as the Hexapoda (including insects ), the head remains free of the thorax. In horseshoe crabs and many crustaceans , a hard shell called the carapace covers the cephalothorax.
56-641: About 74–75 species, see text. 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 . Rhipicephalus ticks are commonly called 'the brown tick' as they are mostly brown in colour. Most adult ticks in this genus do not have colour patterns on their scutum (inornate). This makes the species difficult to distinguish from one another because most are quite similar, but individuals of one particular species can be quite variable. Ticks have traditionally been identified by examination of distinctive morphological features. Most of
112-730: A scutum or hard shield, which the Argasidae lack. The Argasidae contain about 200 species; the genera accepted as of 2010 are Antricola , Argas , Nothoaspis , Ornithodoros , and Otobius . They have no scutum, and the capitulum (mouth and feeding parts) is concealed beneath the body. The phylogeny of the Ixodida within the Acari is shown in the cladogram, based on a 2014 maximum parsimony study of amino acid sequences of 12 mitochondrial proteins. The Argasidae appear monophyletic in this study. Ticks, like mites , belong to
168-425: A blood meal and molting into the nymph stage. In the nymphal and adult stages, ticks have eight legs, each of which has seven segments and is tipped with a pair of claws. The legs are sometimes ornamented and usually bear sensory or tactile hairs. In addition to being used for locomotion , the tarsus of leg I contains a unique sensory structure, Haller's organ , which can detect odors and chemicals emanating from
224-668: A given microclimate – such as sandy soil, hardwood trees, rivers, and the presence of deer – were determined to be good predictors of dense tick populations. Mites and nematodes feed on ticks, which are also a minor nutritional resource for birds. More importantly, ticks act as a disease vector and behave as the primary hosts of many different pathogens such as spirochaetes . Ticks carry various debilitating diseases therefore, ticks may assist in controlling animal populations and preventing overgrazing. Ticks can transmit an array of infectious diseases that affect humans and other animals. Ticks that carry zoonotic pathogens often tend to have
280-402: A meal of blood each time. Often, egg laying and mating occurs detached from the host in a safe environment. The eggs hatch and the larvae feed on a nearby host for anywhere from a few hours to several days, this depends on the species of tick. After they feed the larvae drop and molt into their first nymphal instars, then the nymph seeks out and feeds on its second host, often this is the same as
336-586: A multihost life cycle. Because of their hematophagous (blood-ingesting) diets, ticks act as vectors of many serious diseases that affect humans and other animals. Ticks belong to the Parasitiformes , a distinctive group of mites that are separate from the main group of mites, the Acariformes . 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. Within
392-430: A single species, Nuttalliella namaqua , and as such is a monotypic taxon . Nuttalliella namaqua is found in southern Africa ranging from Tanzania to Namibia and South Africa . Relationships of living and extinct tick families, after Chitimia-Dobler et al. 2022: † Deinocrotonidae Nuttalliellidae Ixodidae Argasidae † Khimairidae The Ixodidae contain over 700 species of hard ticks with
448-413: A soft tick is pear-shaped or oval with a rounded anterior portion. The mouthparts cannot be seen from above, as they are on the ventral surface. A centrally positioned dorsal plate with ridges projecting slightly above the surrounding surface, but with no decoration are often present. Soft ticks possess a leathery cuticle as well. A pattern of small, circular depressions expose where muscles are attached to
504-411: A study of migratory birds passing through Egypt discovered more than half the bird species examined were carrying ticks. It was also observed the tick species varied depending on the season of migration, in this study it is spring and autumn migrations, this is thought to occur due to the seasonal periodicities of the different species. For an ecosystem to support ticks, it must satisfy two requirements;
560-444: A thousand eggs over the course of her lifetime. Both male and female adults feed on blood, and they mate off the host. During feeding, any excess fluid is excreted by the coxal glands, a process that is unique to argasid ticks. Nuttalliellidae is an elusive monotypic family of tick, that is, possesses a single species, Nuttalliella namaqua. There is little to nothing known about the life cycle and feeding habits of N. namaqua but it
616-408: A two-host tick often spans two years. During fall the pregnant female tick will drop off her second host and lay her eggs. The eggs hatch during winter, the following spring the larvae emerge and attach to their first host. Newly hatched larvae attach to a host in order to obtain a blood meal. They remain on the host then develop into nymphs. Once engorged, they drop off the host and find a safe area in
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#1732780124565672-567: A wide host range. The infective agents can be present not only in the adult tick, but also in the eggs produced plentifully by the females. Many tick species have extended their ranges as a result of the movements of people, domesticated pets, and livestock . With increasing participation in outdoor activities such as wilderness hikes , more people and their dogs may find themselves exposed to ticks. All three tick families ticks have four life cycle stages: egg, larva , nymph , and adult. Ixodidae ticks have three different life cycles. Depending on
728-406: Is a feeding structure with mouthparts adapted for piercing skin and sucking blood; it is the front of the head and contains neither the brain nor the eyes. Features of the gnathosoma include two palps , two chelicerae , and hypostome . The hypostome acts as stabilizer and helps to anchor the tick's mouthparts to the host. The chelicerae are specialized appendages used for cutting and piercing into
784-570: Is derived from the Greek word rhiphis , meaning "fan-like", and κεφαλή, kephalē , meaning "head". The two terms are related to the hexagonal basis capituli of Rhipicephalus . Rhipicephalus bursa is a carrier of babesiosis , theileriosis and anaplasmosis in domestic animals, of the Nairobi sheep disease , and an aggressive vector of the agents of the Crimean–Congo hemorrhagic fever and of
840-413: Is different from the typical Rhipicephalus species. Species familiar in the domestic environment include the brown dog tick ( R. sanguineus ). A number of Rhipicephalus spp. females produce phenol and p -cresol after being fed for six days. These compounds may act as sex pheromones since these compounds were shown to be the sex pheromone of Rhipicephalus appendiculatus . The name Rhipicephalus
896-455: Is restricted to a small, shield-like structure behind the capitulum in females and nymphs. When an ixodid attaches to a host the bite is typically painless and generally goes unnoticed. They remain in place until they engorge and are ready to molt ; this process may take days or weeks. Some species drop off the host to molt in a safe place, whereas others remain on the same host and only drop off once they are ready to lay their eggs. The body of
952-416: Is speculated this species of tick has multiple different hosts . Cephalothorax The fovea is the centre of the cephalothorax and is located behind the head (only in spiders). It is often important in identification. It can be transverse or procurved and can, in some tarantulas (e.g. Ceratogyrus darlingi ) have a "horn". The clypeus is the space between the anterior of the cephalothorax and
1008-408: Is they jump onto their host; however, they are incapable of jumping, although static electricity from their hosts has been shown to be capable of pulling the tick over distances several times their own body length. Many tick species, particularly Ixodidae, lie in wait in a position known as "questing". While questing, ticks cling to leaves and grasses by their third and fourth pairs of legs. They hold
1064-531: Is to remove leaf litter, brush, and weeds at the edge of the woods. Ticks like shady, moist leaf litter with an overstory of trees or shrubs and, in the spring, they deposit their eggs into such places allowing larvae to emerge in the fall and crawl into low-lying vegetation. The 3 meter boundary closest to the lawn's edge are a tick migration zone, where 82% of tick nymphs in lawns are found. In general, ticks are found wherever their host species occur. Migrating birds carry ticks with them on through their migrations;
1120-591: 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. Ticks belong to two major families, the Ixodidae or hard ticks, and the Argasidae , or soft ticks. Nuttalliella , a genus of tick from southern Africa, is the only member of the family Nuttalliellidae, and represents
1176-545: Is widely distributed among host taxa, including marsupial and placental mammals, birds, reptiles (snakes, iguanas, and lizards), and amphibians. Ticks of domestic animals cause considerable harm to livestock through pathogenic transmission, causing anemia through blood loss, and damaging wool and hides. The Tropical Bont tick wreaks havoc on livestock and wildlife in Africa, the Caribbean, and several other countries through
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#17327801245651232-409: The Q fever . Tick 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
1288-563: The Ixodidae that have no fixed dwelling place except on the host, they live in sand, in crevices near animal dens or nests, or in human dwellings, where they come out nightly to attack roosting birds or emerge when they detect carbon dioxide in the breath of their hosts. Ixodidae remain in place until they are completely engorged. Their weight may increase by 200 to 600 times compared to their prefeeding weight. To accommodate this expansion, cell division takes place to facilitate enlargement of
1344-523: 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 . Relationships among members of the Parasitiformes, after Klompen, 2010: Opilioacarida Mesostigmata Holothyrida Ixodida (ticks) Fossilized ticks have been discovered from
1400-673: The characteristics used to identify species pertain to male specimens. The immature and female specimens are sometimes simply impossible to identify due to the lack of differential morphological features. Many Rhipicephalus spp. are of economic, medical, and veterinary importance because of their blood feeding lifestyle. They are possible vectors of many pathogens in humans and animals. They can transmit pathogens that cause animal and human diseases, such as East Coast fever , anaplasmosis , babesiosis , rickettsiosis , Boutonneuse fever , Lyme disease , Q fever , Rocky Mountain spotted fever , and Crimean–Congo hemorrhagic fever . In addition to
1456-549: The cuticle. In the Argasidae, the tick's cuticle stretches to accommodate the fluid ingested, but does not grow new cells, with the weight of the tick increasing five- to tenfold over the unfed state. The tick then drops off the host and typically remains in the nest or burrow until its host returns to provide its next meal. Tick saliva contains about 1,500 to 3,000 proteins, depending on the tick species. The proteins with anti-inflammatory properties, called evasins , allow ticks to feed for eight to ten days without being perceived by
1512-571: The end of the Early Cretaceous onwards, most commonly in amber. 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 which does not belong to any living family of tick, the living genus Nuttalliella and the possible nuttalliellid genera Deinocroton and Legionaris , as well as
1568-1353: The essential vitamins that are lacking in blood meal. To overcome these nutritional deficiencies, ticks have evolved obligate interactions with nutritional endosymbionts . The first appearance of ticks and their later diversification were largely conditioned by this nutritional endosymbiosis lasting for millions of years. The most common of these nutritional endosymbionts belong to the Coxiella and Francisella bacterial genera. These intracellular symbiotic microorganisms are specifically associated with ticks and use transovarial transmission to ensure their persistence. Although Coxiella and Francisella endosymbionts are distantly related bacteria, they have converged towards an analogous B vitamin-based nutritional mutualism with ticks. Their experimental elimination typically results in decreased tick survival, molting, fecundity and egg viability, as well as in physical abnormalities, which all are fully restored with an oral supplement of B vitamins. The genome sequencing of Coxiella and Francisella endosymbionts confirmed that they consistently produce three B vitamin types, biotin (vitamin B 7 ), riboflavin (B 2 ) and folate (B 9 ). As they are required for tick life cycle, these obligate endosymbionts are present in all individuals of
1624-441: The fall, and lays thousands of eggs. The larvae hatch in the winter and emerge in the spring. When the larvae emerge, they attach and feed primarily on small mammals and birds. During the summer the larvae become engorged and drop off the first host to molt and become nymphs, this often occurs during the fall. The following spring the nymphs emerge and seek out another host, often a small rodent. The nymphs become engorged and drop off
1680-402: The first host, within an hour. This process occurs repeatedly and until the last nymphal instar occurs, thus allowing the tick to molt into an adult. Once an adult these ticks feed rapidly and periodically their entire life cycle. In some species an adult female may lay eggs after each feeding. Their life cycles range from months to years. The adult female argasid tick can lay a few hundred to over
1736-529: The first pair of legs outstretched, waiting to grasp and climb on to any passing host. Tick questing heights tend to be correlated with the size of the desired host; nymphs and small species tend to quest close to the ground, where they may encounter small mammalian or bird hosts; adults climb higher into the vegetation, where larger hosts may be encountered. Some species are hunters and lurk near places where hosts may rest. Upon receiving an olfactory stimulus or other environmental indication, they crawl or run across
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1792-579: The forest floor or absorb water from subsaturated air by secreting hygroscopic fluid produced by the salivary glands onto the external mouthparts and then reingesting the water-enriched fluid. Ticks can withstand temperatures just above −18 °C (0 °F) for more than two hours and can survive temperatures between −7 and −2 °C (20 and 29 °F) for at least two weeks. Ticks have even been found in Antarctica, where they feed on penguins. Most ticks are plain brown or reddish brown. However,
1848-471: The host animal. Researchers are studying these evasins with the goal of developing drugs to neutralise the chemokines that cause myocarditis , heart attack, and stroke. Ticks do not use any other food source than vertebrate blood and therefore ingest high levels of protein, iron and salt, but few carbohydrates, lipids or vitamins. Ticks’ genomes have evolved large repertoires of genes related to this nutritional challenge, but they themselves cannot synthesize
1904-505: The host in the fall to molt and become adults. The following spring the adult ticks emerge and seek out a larger host, often a large mammal such as cattle or even humans. Females will mate on their third host. Female adults then engorge on blood and prepare to drop off to lay her eggs on the ground, while males feed very little and remain on the host in order to continue mating with other females. Argasid ticks, unlike ixodid ticks, may go through up to seven nymphal stages (instars), requiring
1960-399: The host's skin while palps are leglike appendages that are sensory in function. The ventral side of the idiosoma bears sclerites , and the gonopore is located between the fourth pair of legs. In the absence of segmentation, the positioning of the eyes, limbs, and gonopore on the idiosoma provide the only locational guidance. Larval ticks hatch with six legs, acquiring the other two after
2016-702: The host, as well as sensing changes in temperature and air currents. Ticks can also use Haller's organs to perceive infrared light emanating from a host. When stationary, their legs remain tightly folded against the body. Ticks are extremely resilient animals. They can survive in a near vacuum for as long as half an hour. Their slow metabolism during their dormant periods enables them to go prolonged durations between meals. Even after 18 weeks of starvation, they can endure repeated two-day bouts of dehydration followed by rehydration, but their survivability against dehydration drops rapidly after 36 weeks of starvation. To keep from dehydrating, ticks hide in humid spots on
2072-471: The host. After engorging on the host's blood, the nymphs molt into sexually mature adults that remain on the host in order to feed and mate. Once a female is both fed and ready to lay eggs, only then does she leave the host in search of a suitable area to deposit her eggs. Ticks that follow this life cycle are called one-host ticks. The winter tick Dermacentor albipictus and the cattle tick Boophilus microplus are examples of one-host ticks. The life cycle of
2128-556: The infectious agents spread by ticks, tick bites can lead to allergic and toxic reactions. A toxic reaction occur when they inject a neurotoxin with their bite that leads to tick-caused paralysis . Boophilus was once considered a separate genus, but studies in the early 2000s resulted in Boophilus being made a subgenus of Rhipicephalus . Although Boophilus has been included in the Rhipicephalus genus, their morphology
2184-408: The interior of the integument . The eyes are on the sides of the body, the spiracles open between legs 3 and 4, and males and females only differ in the structure of the genital pore. Nuttalliellidae can be distinguished from both ixodid and argasid ticks by a combination of a projecting gnathosoma and a soft leathery skin. Other distinguishing characteristics include the position of the stigmata ,
2240-483: The intervening surface. Other ticks, mainly the Argasidae, are nidicolous , finding hosts in their nests, burrows, or caves. They use the same stimuli as non-nidicolous species to identify hosts, with body heat and odors often being the main factors. Many of them feed primarily on birds , though some Ornithodoros species, for example, feed on small mammals . Both groups of soft tick feed rapidly, typically biting painfully and drinking their fill within minutes. Unlike
2296-469: The lack of setae, the strongly corrugated integument, and the form of the fenestrated plates. Ticks are ectoparasites and consume blood to satisfy all of their nutritional requirements. They are obligate hematophages , and require blood to survive and move from one stage of life to another. Ticks can fast for long periods of time, but eventually die if unable to find a host. Hematophagy evolved independently at least six times in arthropods living during
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2352-470: The last common ancestor of all living ticks likely lived around 195 million years ago in the Southern Hemisphere, in what was then Gondwana. Ticks belong to three different families. The majority of tick species belong to the two families: Ixodidae (hard ticks) and Argasidae (soft ticks). The third living family is Nuttalliellidae , named for the bacteriologist George Nuttall . It comprises
2408-421: The late Cretaceous ; in ticks it is thought to have evolved 120 million years ago through adaptation to blood-feeding. This behavior evolved independently within the separate tick families as well, with differing host-tick interactions driving the evolutionary change. Some ticks attach to their host rapidly, while others wander around searching for thinner skin, such as that in the ears of mammals. Depending on
2464-540: The 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 . An undescribed juvenile tick is known from late Albian amber , dating to 105 million years ago. The younger Baltic and Dominican ambers have also yielded examples that can be placed in living genera. A phylogenetic analysis suggests that
2520-418: The most primitive living lineage of ticks. Adults have ovoid/pear-shaped bodies (idiosomas) which become engorged with blood when they feed, and eight legs. Their cephalothorax and abdomen are completely fused. 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
2576-625: The natural environment in which to molt into adults, this typically occurs during the winter. Both male and female adults seek out a host on which to attach, which may be the same body that served as host during their early development but is often a larger mammal. Once attached, they feed and mate. Gravid females drop from the host to oviposit in the environment. Ticks that complete their life cycle in this manner are called two-host ticks, like Hyalomma anatolicum excavatum. Most ixodid ticks require three hosts, and their life cycles typically span three years. The female tick drops off its host, often in
2632-434: The ocularium. It is found in most arachnids. It is connected to the labrum of the invertebrate, between the labrum and the face. The ocularium is a "turret" for the ocelli found in most arachnids. In harvestmen , it may have the ornament of spines. The trident is a small group of (usually three) spines found in harvestmen exclusively. It is located in front of the ocularium. It varies in size amongst species; in some it
2688-473: The population density of host species in the area must be great enough and it must be humid enough for ticks to remain hydrated. Due to their role in transmitting Lyme disease , Ixodid ticks, particularly the North American I. scapularis , have been studied using geographic information systems to develop predictive models for ideal tick habitats. According to these studies, certain features of
2744-413: The scuta of some species are decorated with white patterns. In nymphs and adults, the capitulum is prominent and projects forwards from the body. The eyes are close to the sides of the scutum and the large spiracles are located just behind the coxae of the fourth pair of legs. The hard protective scutellum , a characteristic of this family, covers nearly the whole dorsal surface in males, but
2800-544: The species and life stage, preparing to feed can take from ten minutes to two hours. On locating a suitable feeding spot, the tick grasps the host's skin and cuts into the surface. It extracts blood by cutting a hole in the host's epidermis , into which it inserts its hypostome and prevents the blood from clotting by excreting an anticoagulant or platelet aggregation inhibitor. Ticks find their hosts by detecting an animals' breath and body odors, sensing body heat, moisture, or vibrations. A common misconception about ticks
2856-401: The species, Ixodids can either possess a one-host life cycle, two-host life cycle, or three-host life cycle. In one-host ticks the tick remains on the host through the larval, nymphal, and adult stages, only to leave the host to lay eggs. Eggs laid in the environment hatch into larvae, which immediately seek out a host in which to attach and feed. Fed larvae molt into unfed nymphs that remain on
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#17327801245652912-411: The spread of disease, specifically heartwater disease. The spinose ear tick has a worldwide distribution, the young feed inside the ears of cattle and various wildlife. A habitat preferred by ticks is the interface where a lawn meets the forest, or more generally, the ecotone , which is unmaintained transitional edge habitat between woodlands and open areas. Therefore, one tick management strategy
2968-464: The subclass Acari that lack their primary somatic segmentation of the abdomen (or opisthosoma ), rather these parasitic arachnids present a subsequent fusion of the abdomen with the cephalothorax (or prosoma ). The tagmata typical of other Chelicerata have developed into the gnathosoma (head), which is retractable and contains the mouthparts, and idiosoma (body), which contains the legs, digestive tract, and reproductive organs. The gnathosoma
3024-431: The tick species they infect, at least at early stages of development since they may be secondarily lost in males during nymphal development. Since Coxiella and Francisella endosymbionts are closely related to pathogens, there is a substantial risk of misidentification between endosymbionts and pathogens, leading to an overestimation of infection risks associated with ticks. Tick species are widely distributed around
3080-460: The underside of their bodies. Ticks locate potential hosts by sensing odor, body heat, moisture, and/or vibrations in the environment. Ticks have four stages to their life cycle, namely egg, larva , nymph , and adult. Ticks belonging to the Ixodidae family undergo either a one-host, two-host, or three-host life cycle . Argasid ticks have up to seven nymphal stages ( instars ), each one requiring blood ingestion, and as such, Argasid ticks undergo
3136-423: The world. They tend to flourish more in warm, humid climates, because they require a certain amount of moisture in the air to undergo metamorphosis , and low temperatures inhibit their development of eggs to larvae. The occurrence of ticks and tick-borne illnesses in humans is increasing. Tick populations are spreading into new areas, due in part to the warming temperatures of climate change . Tick parasitism
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