83-394: 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
166-1145: A 2011 study, that number was increased to fifty-one total specimens. They were collected in three locations in South Africa including two new sites: Springbok, Graaff-Reinet, and Heuningvleipan. In 2024, 5 fossil species of the genus were described from Burmese amber in Myanmar, dating to the mid- Cretaceous , around 100 million years ago. In this study, it was suggested that the extinct genera Deinocroton and Legionaris also known from Burmese amber should also be included in Nuttalliellidae. Nuttalliella namaqua has been observed in Tanzania, Namibia and South Africa. Localities of collection include coastal (west and south) and inland sites (north). The Namibia specimens were collected from museum mammal skins in Kuboes . The biomes represented by these locations are: mixed tree and shrub savannah, Nama Karoo and Succulent Karoo . N. namaqua
249-461: A bundle from a small chamber connected to the spiracle . This type of tracheal system has almost certainly evolved from the book lungs, and indicates that the tracheae of arachnids are not homologous with those of insects. Further adaptations to terrestrial life are appendages modified for more efficient locomotion on land, internal fertilisation, special sensory organs, and water conservation enhanced by efficient excretory structures as well as
332-444: A clade called Arachnopulmonata was also well supported. Pseudoscorpiones may also belong here, as all six orders share the same ancient whole genome duplication , and analyses support pseudoscorpions as the sister group of scorpions. Genetic analysis has not yet been done for Ricinulei, Palpigradi, or Solifugae, but horseshoe crabs have gone through two whole genome duplications, which gives them five Hox clusters with 34 Hox genes ,
415-470: A fourth pair usually appears when they moult into nymphs . However, mites are variable: as well as eight, there are adult mites with six or, like in Eriophyoidea , even four legs. While the adult males in some members of Podapolipidae have six legs, the adult females have only a single pair. Arachnids are further distinguished from insects by the fact they do not have antennae or wings . Their body
498-665: 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
581-544: 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
664-400: 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
747-572: 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
830-413: 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
913-410: 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;
SECTION 10
#1733094426999996-413: A thin membrane. Inside the pit, a small hair touches the underside of the membrane, and detects its motion. Slit sense organs are believed to be involved in proprioception , and possibly also hearing. Arachnids may have one or two gonads , which are located in the abdomen. The genital opening is usually located on the underside of the second abdominal segment. In most species, the male transfers sperm to
1079-443: 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
1162-427: A transverse fold of the ectoderm . The ancestors of modern arachnids probably had both types, but modern ones often lack one type or the other. The cornea of the eye also acts as a lens, and is continuous with the cuticle of the body. Beneath this is a transparent vitreous body, and then the retina and, if present, the tapetum. In most arachnids, the retina probably does not have enough light sensitive cells to allow
1245-407: 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
1328-435: A waxy layer covering the cuticle. The excretory glands of arachnids include up to four pairs of coxal glands along the side of the prosoma, and one or two pairs of Malpighian tubules , emptying into the gut. Many arachnids have only one or the other type of excretory gland, although several do have both. The primary nitrogenous waste product in arachnids is guanine . Arachnid blood is variable in composition, depending on
1411-565: 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
1494-404: 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 a scutum or hard shield, which
1577-404: 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
1660-505: Is derived from the Greek word ἀράχνη ( aráchnē , 'spider'), from the myth of the hubristic human weaver Arachne , who was turned into a spider. Almost all adult arachnids have eight legs, unlike adult insects which all have six legs. However, arachnids also have two further pairs of appendages that have become adapted for feeding, defense, and sensory perception. The first pair, the chelicerae , serve in feeding and defense. The next pair,
1743-442: Is genus of tick . It contains a single living species, Nuttalliella namaqua found in southern Africa , having been reported from Tanzania , Namibia and South Africa . The genus is placed in its own family, Nuttalliellidae . It can be distinguished from ixodid ticks and argasid ticks by a combination of characteristics including the position of the stigmata , lack of setae , strongly corrugated integument , and form of
SECTION 20
#17330944269991826-403: Is organized into two tagmata , called the prosoma and opisthosoma , also referred to as the cephalothorax and abdomen . However, there are questions about the validity of the latter terms. While the term cephalothorax implies a fused cephalon (head) and thorax , there is currently neither fossil nor embryological evidence that arachnids ever had a separate thorax-like division. Likewise,
1909-453: 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
1992-422: Is speculated this species of tick has multiple different hosts . Arachnid Arachnids are arthropods in the class Arachnida ( / ə ˈ r æ k n ɪ d ə / ) of the subphylum Chelicerata . Arachnida includes, among others, spiders , scorpions , ticks , mites , pseudoscorpions , harvestmen , camel spiders , whip spiders and vinegaroons . Adult arachnids have eight legs attached to
2075-407: 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
2158-529: 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;
2241-534: 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
2324-507: The cephalothorax . In some species the frontmost pair of legs has converted to a sensory function, while in others, different appendages can grow large enough to take on the appearance of extra pairs of legs. Almost all extant arachnids are terrestrial , living mainly on land. However, some inhabit freshwater environments and, with the exception of the pelagic zone , marine environments as well. They comprise over 110,000 named species , of which 51,000 are species of spiders. The term
2407-509: The cladogram below. Including fossil taxa does not fundamentally alter this view, although it introduces some additional basal groups. Chelicerata (sea spiders, horseshoe crabs and arachnids ) [REDACTED] [REDACTED] [REDACTED] Myriapoda (centipedes, millipedes, and allies) [REDACTED] [REDACTED] Pancrustacea (crustaceans and hexapods) [REDACTED] [REDACTED] The extant chelicerates comprise two marine groups: Sea spiders and horseshoe crabs, and
2490-668: The fenestrated plates. It is the most basal lineage of living ticks. The first description by G.A.H. Bedford in 1931 was based upon a single female collected under a stone at Kamieskroon, in Little Namaqualand , by Dr R.F. Lawrence in October 1930. The genus and family were named for the bacteriologist George Nuttall , a specialist in diseases transmitted by ticks. The species was recognised as distinctive enough to warrant its own family in two publications in 1935 and 1936. As of 1980, only eighteen specimens had been collected. In
2573-424: The house dust mite , are also the only arachnids able to ingest solid food, which exposes them to internal parasites, although it is not unusual for spiders to eat their own silk. And one species of spider is mostly herbivorous. Scorpions, spiders and pseudoscorpions secrete venom from specialized glands to kill prey or defend themselves. Their venom also contains pre-digestive enzymes that helps breaking down
Tick - Misplaced Pages Continue
2656-453: The pedipalps , have been adapted for feeding, locomotion, and/or reproductive functions. In scorpions, pseudoscorpions, and ricinuleids the pedipalps end in a pair of pinchers, while in whip scorpions, Schizomida , Amblypygi , and most harvestmen, they are raptorial and used for prey capture. In Solifugae , the palps are quite leg-like, so that these animals appear to have ten legs. The larvae of mites and Ricinulei have only six legs;
2739-453: The 'abdomen' of many arachnids contains organs atypical of an abdomen, such as a heart and respiratory organs. The cephalothorax is usually covered by a single, unsegmented carapace. The abdomen is segmented in the more primitive forms, but varying degrees of fusion between the segments occur in many groups. It is typically divided into a preabdomen and postabdomen, although this is only clearly visible in scorpions, and in some orders, such as
2822-679: 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
2905-545: 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
2988-557: 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
3071-519: 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 the end of
3154-436: The abdomen has no appendages. Like all arthropods, arachnids have an exoskeleton , and they also have an internal structure of cartilage -like tissue, called the endosternite , to which certain muscle groups are attached. The endosternite is even calcified in some Opiliones . Most arachnids lack extensor muscles in the distal joints of their appendages. Spiders and whip scorpions extend their limbs hydraulically using
3237-409: The arachnids has proven difficult as of March 2016 , with successive studies producing different results. A study in 2014, based on the largest set of molecular data to date, concluded that there were systematic conflicts in the phylogenetic information, particularly affecting the orders Acariformes , Parasitiformes and Pseudoscorpiones , which have had much faster evolutionary rates. Analyses of
3320-547: 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
3403-920: The data using sets of genes with different evolutionary rates produced mutually incompatible phylogenetic trees . The authors favoured relationships shown by more slowly evolving genes, which demonstrated the monophyly of Chelicerata, Euchelicerata and Arachnida, as well as of some clades within the arachnids. The diagram below summarizes their conclusions, based largely on the 200 most slowly evolving genes; dashed lines represent uncertain placements. Acariformes [REDACTED] Opiliones [REDACTED] Ricinulei [REDACTED] Solifugae [REDACTED] Parasitiformes [REDACTED] Pseudoscorpiones [REDACTED] Scorpiones [REDACTED] Araneae [REDACTED] Amblypygi [REDACTED] Uropygi (Thelyphonida s.s. ) [REDACTED] Tetrapulmonata , here consisting of Araneae , Amblypygi and Uropygi (Thelyphonida s.s. ) ( Schizomida
Tick - Misplaced Pages Continue
3486-1335: 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
3569-419: The eyes to form a proper image. In addition to the eyes, almost all arachnids have two other types of sensory organs. The most important to most arachnids are the fine sensory hairs that cover the body and give the animal its sense of touch. These can be relatively simple, but many arachnids also possess more complex structures, called trichobothria . Finally, slit sense organs are slit-like pits covered with
3652-440: 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
3735-554: The female in a package, or spermatophore . The males in harvestmen and some mites have a penis. Complex courtship rituals have evolved in many arachnids to ensure the safe delivery of the sperm to the female. Members of many orders exhibit sexual dimorphism. Arachnids usually lay yolky eggs , which hatch into immatures that resemble adults. Scorpions, however, are either ovoviviparous or viviparous , depending on species, and bear live young. Also some mites are ovoviviparous and viviparous, even if most lay eggs. In most arachnids only
3818-640: The females provide parental care, with harvestmen being one of the few exceptions. The phylogenetic relationships among the main subdivisions of arthropods have been the subject of considerable research and dispute for many years. A consensus emerged from about 2010 onwards, based on both morphological and molecular evidence; extant (living) arthropods are a monophyletic group and are divided into three main clades: chelicerates (including arachnids), pancrustaceans (the paraphyletic crustaceans plus insects and their allies), and myriapods (centipedes, millipedes and allies). The three groups are related as shown in
3901-402: 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
3984-529: 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
4067-489: The food. It extends through most of the body, and connects to a short sclerotised intestine and anus in the hind part of the abdomen. Arachnids have two kinds of eyes: the lateral and median ocelli . The lateral ocelli evolved from compound eyes and may have a tapetum , which enhances the ability to collect light. With the exception of scorpions, which can have up to five pairs of lateral ocelli, there are never more than three pairs present. The median ocelli develop from
4150-570: 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,
4233-557: The highest number found in any invertebrate, yet it is not clear if the oldest genome duplication is related to the one in Arachnopulmonata. Onychophora [REDACTED] Mandibulata [REDACTED] [REDACTED] [REDACTED] Pycnogonida [REDACTED] † Chasmataspidida [REDACTED] † Eurypterida [REDACTED] Parasitiformes [REDACTED] Acariformes [REDACTED] Pseudoscorpiones [REDACTED] Nuttalliellidae Nuttalliella
SECTION 50
#17330944269994316-469: 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
4399-503: 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
4482-430: 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 a blood meal and molting into
4565-470: 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
4648-406: 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 ,
4731-481: 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
4814-466: 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
4897-514: 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 a single species, Nuttalliella namaqua , and as such
4980-418: 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
5063-527: 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
SECTION 60
#17330944269995146-475: The mites, the abdominal sections are completely fused. A telson is present in scorpions, where it has been modified to a stinger, and into a flagellum in the Palpigradi , Schizomida (very short) and whip scorpions . At the base of the flagellum in the two latter groups there are glands which produce acetic acid as a chemical defense. Except for a pair of pectines in scorpions, and the spinnerets in spiders,
5229-486: The mode of respiration. Arachnids with an efficient tracheal system do not need to transport oxygen in the blood, and may have a reduced circulatory system. In scorpions and some spiders, however, the blood contains haemocyanin , a copper-based pigment with a similar function to haemoglobin in vertebrates. The heart is located in the forward part of the abdomen, and may or may not be segmented. Some mites have no heart at all. Arachnids are mostly carnivorous , feeding on
5312-418: 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
5395-416: The mouth. Behind the mouth is a muscular, sclerotised pharynx , which acts as a pump, sucking the food through the mouth and on into the oesophagus and stomach . In some arachnids, the oesophagus also acts as an additional pump. The stomach is tubular in shape, with multiple diverticula extending throughout the body. The stomach and its diverticula both produce digestive enzymes and absorb nutrients from
5478-624: 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
5561-540: 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 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
5644-554: 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
5727-465: 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
5810-457: The pre-digested bodies of insects and other small animals. But ticks, and many mites, are parasites, some of which are carriers of disease. The diet of mites also include tiny animals, fungi, plant juices and decomposing matter. Almost as varied is the diet of harvestmen , where we will find predators, decomposers and omnivores feeding on decaying plant and animal matter, droppings, animals and mushrooms. The harvestmen and some mites, such as
5893-460: The pressure of their hemolymph . Solifuges and some harvestmen extend their knees by the use of highly elastic thickenings in the joint cuticle. Scorpions, pseudoscorpions and some harvestmen have evolved muscles that extend two leg joints (the femur-patella and patella-tibia joints) at once. The equivalent joints of the pedipalps of scorpions though, are extended by elastic recoil. There are characteristics that are particularly important for
5976-407: The prey. The saliva of ticks contains anticoagulants and anticomplements, and several species produce a neurotoxin . Arachnids produce digestive enzymes in their stomachs, and use their pedipalps and chelicerae to pour them over their dead prey. The digestive juices rapidly turn the prey into a broth of nutrients, which the arachnid sucks into a pre-buccal cavity located immediately in front of
6059-411: 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
6142-540: 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
6225-401: 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
6308-408: 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
6391-462: 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
6474-487: The terrestrial arachnids. These have been thought to be related as shown below. (Pycnogonida (sea spiders) may be excluded from the chelicerates, which are then identified as the group labelled "Euchelicerata". ) A 2019 analysis nests Xiphosura deeply within Arachnida. Pycnogonida (sea spiders) [REDACTED] Xiphosura (horseshoe crabs) [REDACTED] Arachnida [REDACTED] Discovering relationships within
6557-432: The terrestrial lifestyle of arachnids, such as internal respiratory surfaces in the form of tracheae , or modification of the book gill into a book lung , an internal series of vascular lamellae used for gas exchange with the air. While the tracheae are often individual systems of tubes, similar to those in insects, ricinuleids, pseudoscorpions, and some spiders possess sieve tracheae, in which several tubes arise in
6640-426: 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
6723-458: 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
6806-418: 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
6889-498: Was not included in the study), received strong support. Somewhat unexpectedly, there was support for a clade comprising Opiliones , Ricinulei and Solifugae , a combination not found in most other studies. In early 2019, a molecular phylogenetic analysis placed the horseshoe crabs, Xiphosura , as the sister group to Ricinulei. It also grouped pseudoscorpions with mites and ticks, which the authors considered may be due to long branch attraction . The addition of Scorpiones to produce
#998001