The evolutionary ancestry of arthropods dates back to the Cambrian period. The group is generally regarded as monophyletic, and many analyses support the placement of arthropods with cycloneuralians (or their constituent clades) in a superphylum Ecdysozoa. Overall, however, the basal relationships of animals are not yet well resolved. Likewise, the relationships between various arthropod groups are still actively debated. Today, arthropods contribute to the human food supply both directly as food, and more importantly, indirectly as pollinators of crops. Some species are known to spread severe disease to humans, livestock, and crops. (Full article...)
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Cimex lectularius
The Cimicidae are a family of small parasiticbugs that feed exclusively on the blood of warm-blooded animals. They are called cimicids or, loosely, bed bugs, though the latter term properly refers to the most well-known member of the family, Cimex lectularius, the common bed bug and its tropical relation Cimex hemipterus. The family contains over 100 species. Cimicids appeared in the fossil record in the Cretaceous period. When bats evolved in the Eocene, Cimicids switched hosts and now feed mainly on bats or birds. Members of the group have colonised humans on three occasions.
Cimicids usually feed on their host's blood every three to seven days, crawling away from the host and hiding while they digest the blood, which may take several days. This means that they specialise in vertebrate hosts that return regularly to particular sites to nest, roost or sleep. Birds and bats suit these specific requirements, as do humans now that they live in dwellings, and these are the main hosts used by the bugs. Most cimicids are able to go for long periods without feeding, over a year in some instances.
Cimicids are typically small, oval, flattened, wingless insects. They are stimulated to appear from their hiding places by cues such as a slight rise in the temperature of their surroundings. Among the family's distinctive characteristics are traumatic insemination, in which the male fertilises the eggs by piercing the female's abdominal wall with his intromittent organ. They also have distinctive paired structures called mycetomes inside their bodies, in which they harbour bacterial symbionts: these may help them to obtain nutrients they cannot get from blood. Although the insects may acquire viruses and other pathogens while feeding, these do not normally replicate inside the insect, and the infections are not transmitted to new hosts. (Full article...)
Out of the four described species of Slimonia, three measured below or up to 20 centimetres (7.9 in) in length. Only S. acuminata was larger, with the largest specimens measuring 100 centimetres (39 in) in length. Though this is large for a predatory arthropod, Slimonia would be exceeded in length by later and more derived (more "advanced") members of the closely related pterygotid family of eurypterids, which would become the largest known arthropods to ever live. (Full article...)
It is a poorly-known genus whose carapace (dorsal plate of the prosoma, head) was semiovate bordered by a marginal rim, with eyeslaterally placed, a preabdomen and postabdomen (the two halves of the abdomen) with six segments each and a short spike-like telson (which was the posteriormost division of the body). It reached a total length of 7.5 centimetres (2.9 inches). These characteristics place Tylopterella in the familyOnychopterellidae together with Onychopterella and Alkenopterus.
Tylopterella is notable for its thick ornamentation and general body surface. Its paired tubercles or knobs in the top of its second to fifth segments differentiates it from many other eurypterids. This thickness that its body possessed is due to the highly saline conditions to which Tylopterella had to adapt in the Guelph Formation; other organisms with reinforced shells have also been found in the same place. (Full article...)
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Ammophila sabulosa taking nectar on a hemp agrimony flower head
Ammophila sabulosa, the red-banded sand wasp, is a species of the subfamily Ammophilinae of the solitary hunting wasp family Sphecidae, also called digger wasps. Found across Eurasia, the parasitoid wasp is notable for the mass provisioning behaviour of the females, hunting caterpillars mainly on sunny days, paralysing them with a sting, and burying them in a burrow with a single egg. The species is also remarkable for the extent to which females parasitise their own species, either stealing prey from nests of other females to provision their own nests, or in brood parasitism, removing the other female's egg and laying one of her own instead. (Full article...)
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Black-headed sugar ant worker from Strangways, Victoria
The black-headed sugar ant (Camponotus nigriceps), also known as the brown sugar ant, is a species of Formicinaeant endemic to Australia. Found throughout most states, the species is a member of the genus Camponotus, a cosmopolitan genus of ants commonly known as carpenter ants. It was formally described and named by British entomologist Frederick Smith in 1858. These ants are characterised by their black head, reddish-brown mesosoma and black gaster, which can change in colour.
The species is polymorphic: workers and soldiers measure 6 to 12 millimetres (0.24 to 0.47 in) and males are 12 millimetres (0.47 in). The queens are the largest members of the colony, measuring 16 millimetres (0.63 in). Colonies dwell in dry regions, including open areas or in dry sclerophyll woodland, where they nest in soil, large mounds or under stones. Nuptial flight occurs in summer and nests can hold several thousand individuals. Considered a household pest, black-headed sugar ants feed on sweet foods and insects and tend to butterfly larvae. Numerous birds and fish prey on these ants. (Full article...)
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Myrmecia inquilina is a species of ant endemic to Australia in the subfamily Myrmeciinae, first discovered in 1955 and described by Athol Douglas and William Brown Jr. in 1959. These ants are large, measuring 21.4 millimetres (0.84 in). During the time of its discovery, Douglas and Brown announced M. inquilina as the first social parasite among the primitive subfamilies, and today it is one of the two known Myrmecia species to have no worker caste. Two host species are known, Myrmecia nigriceps and Myrmecia vindex. Aggression between M. inquilina and its host species does not occur, and colonies may only produce M. inquilina brood months after the inquiline queens begin to lay their eggs. Queens eat the colony brood or trophic eggs, and other Myrmecia species may kill M. inquilina queens if they reject them. Due to its restricted distribution and threats to its habitat, the ant is "vulnerable" according to the IUCN Red List. (Full article...)
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Fossil of C. newlini, the telson is inaccurately reconstructed
Carcinosomatid eurypterids had unusual proportions and features compared to other eurypterids, with a broad abdomen, thin and long tail and spined and forward-facing walking appendages. They were not as streamlined as other groups but had considerably more robust and well developed walking appendages. In Carcinosoma, these spined walking appendages are thought to have been used to create a trap to capture prey in. The telson (the posteriormost division of the body) of Carcinosoma appears to have possessed distinct segmentation, Carcinosoma is the only known eurypterid to possess this feature.
At 2.2 meters (7.2 ft) in length, the species C. punctatum is the largest carcinosomatoid eurypterid by far and is among the largest eurypterids overall, rivalling the large pterygotid eurypterids (such as Jaekelopterus) in size. Other species of the genus were considerably smaller, with most ranging from 70 centimeters (2.3 ft) to 100 centimeters (3.3 ft) in length. (Full article...)
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Illustration of PWL2013/5224-LS, the type specimen of W. noctua
Wiedopterus is a genus of eurypterid, an extinct group of aquatic arthropods. The type and only species of Wiedopterus, W. noctua, is known from deposits of Early Devonian age in Germany. The generic name derives from the Wied river, which runs near the site of the initial discovery, and the species name, noctua, derives from Latinnoctua (owl) which refers to the superficial resemblance of the carapace (head plate) to an owl.
A small eurypterid, the type and only known specimen of Wiedopterus does not preserve the appendages or the underside of the body, making certain classification of the genus impossible. As such, it is formally classified as Eurypterinaincertae sedis (indicating uncertain placement within the Eurypterina suborder of eurypterids). Though not yet formally classified as such, Wiedopterus was suggested to probably belong to the Adelophthalmidae family on account of various features, including its general body outline, the position of its eyes, the first segment after its head being reduced in size as well as there being longitudinal ridges on the posterior segments of its body. (Full article...)
Wesołowska published her first work in 1981, which included the description of nine new species of spiders, the first in what would be a prolific career. She moved to the University of Wrocław to continue her studies, and completed her doctoral thesis that described 44 new species of the genus Heliophanus. She joined the faculty of the University of Wrocław in 1985, received a habilitation in 2000, and remained a tenured professor at the university until her retirement in 2020.
Her research has focused on the description, taxonomy and zoogeography of jumping spiders, and has included extensive work on African genera like Menemerus and Pachyballus. Wesołowska has identified more than 500 species, including half of all those from South Africa, and more than 20 species have been named after her. (Full article...)
With a body length of 54 cm (21 in), Megarachne was a medium-sized eurypterid. If the original identification as a spider had been correct, Megarachne would have been the largest known spider to have ever lived. Eurypterids such as Megarachne are often called "sea scorpions", but the strata in which Megarachne has been found indicates that it dwelled in freshwater and not in marine environments.
Megarachne was similar to other eurypterids within the Mycteropoidea, a rare group known primarily from South Africa and Scotland. The mycteropoids had evolved a specialized method of feeding referred to as sweep-feeding. This involved raking through the substrate of riverbeds in order to capture and eat smaller invertebrates. Despite only two specimens having been recovered, Megarachne represents the most complete eurypterid discovered in Carboniferous deposits in South America so far. Due to their fragmentary fossil record and similarities between the genera, some researchers have hypothesized that Megarachne and two other members of its family, Mycterops and Woodwardopterus, represent different developmental stages of a single genus. (Full article...)
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Psylliodes luridipennis, commonly known as the Lundy cabbage flea beetle or the bronze Lundy cabbage flea beetle, is a species of flea beetle endemic to the island of Lundy, where it lives and feeds upon the endemic Lundy cabbage (Coincya wrightii). Along with the true weevilCeutorhynchus contractus var. pallipes and an undescribed race of flea beetle Psylliodes napi, it is known only from the Lundy cabbage. The species was first recorded by Thomas Vernon Wollaston in the 1840s, and was named by the Austrian entomologist Franz Kutschera in 1864.
Adult Lundy cabbage flea beetle measure around 3 millimetres (0.12 in) in length. They have brassy-green heads and bodies, with reddish-brown elytra. The adults feed upon the leaves of the Lundy cabbage, while the larvae mine into the plants to feed. The species is threatened by fluctuating numbers of Lundy cabbages, particularly due to invasive common rhododendrons (Rhododendron ponticum). (Full article...)
A dragonfly is a flying insect belonging to the infraorderAnisoptera below the orderOdonata. About 3,000 extant species of dragonflies are known. Most are tropical, with fewer species in temperate regions. Loss of wetland habitat threatens dragonfly populations around the world. Adult dragonflies are characterised by a pair of large, multifaceted, compound eyes, two pairs of strong, transparent wings, sometimes with coloured patches, and an elongated body. Many dragonflies have brilliant iridescent or metallic colours produced by structural coloration, making them conspicuous in flight. An adult dragonfly's compound eyes have nearly 24,000 ommatidia each.
Dragonflies can be mistaken for the closely related damselflies, which make up the other odonatan infraorder (Zygoptera) and are similar in body plan, though usually lighter in build; however, the wings of most dragonflies are held flat and away from the body, while damselflies hold their wings folded at rest, along or above the abdomen. Dragonflies are agile fliers, while damselflies have a weaker, fluttery flight.
Dragonflies are predatory insects, both in their aquatic nymphal stage (also known as "naiads") and as adults. In some species, the nymphal stage lasts up to five years, and the adult stage may be as long as 10 weeks, but most species have an adult lifespan in the order of five weeks or less, and some survive for only a few days. They are fast, agile fliers capable of highly accurate aerial ambush, sometimes migrating across oceans, and often live near water. They have a uniquely complex mode of reproduction involving indirect insemination, delayed fertilisation, and sperm competition. During mating, the male grasps the female at the back of the head, and the female curls her abdomen under her body to pick up sperm from the male's secondary genitalia at the front of his abdomen, forming the "heart" or "wheel" posture. Dragonflies make use of motion camouflage when attacking prey or rivals. (Full article...)
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Avitomyrmex is an extinct genus of bulldog ants in the subfamily Myrmeciinae which contains three described species. The genus was described in 2006 from Ypresian stage (Early Eocene) deposits of British Columbia, Canada. Almost all the specimens collected are queens, with an exception of a single fossilised worker. These ants are large, and the eyes are also large and well-developed; a sting is present in one species. The behaviour of these ants may have been similar to extant Myrmeciinae ants, such as foraging solitarily for arthropod prey and never leaving pheromone trails to food sources. Avitomyrmex has not been assigned to any tribe, instead generally being regarded as incertae sedis within Myrmeciinae. However, its identity as an ant has been challenged, although it is undoubtedly a hymenopteran insect. (Full article...)
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Male Unicorn sikus, viewed from above (legs omitted).
Unicorn ("one horn", in Latin) is a genus of goblin spiders (family Oonopidae) from South America, containing seven species that occur predominantly in high elevation, semi-desert regions of Bolivia, Chile, and Argentina. Individuals are relatively large for goblin spiders, measuring up to 3.0 mm (0.12 in) in body length. The genus name refers to a characteristic pointed projection between the eyes and jaws of males. In at least one species, broken-off tips of the male pedipalps have been found within the genitalia of females, postulated as a means of sperm competition. Unicorn possesses several traits that suggest it is a relatively "primitive" member of the Oonopidae, and is classified with other similar, soft-bodied goblin spiders in the subfamily Sulsulinae. (Full article...)
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Varroa destructor, the Varroa mite, is an external parasiticmite that attacks and feeds on honey bees and is one of the most damaging honey bee pests in the world. A significant mite infestation leads to the death of a honey bee colony, usually in the late autumn through early spring. Without management for Varroa mite, honey bee colonies typically collapse within 2 to 3 years in temperate climates. These mites can infest Apis mellifera, the western honey bee, and Apis cerana, the Asian honey bee. Due to very similar physical characteristics, this species was thought to be the closely related Varroa jacobsoni prior to 2000, but they were found to be two separate species after DNA analysis.
Parasitism of bees by mites in the genus Varroa is called varroosis. The Varroa mite can reproduce only in a honey bee colony. It attaches to the body of the bee and weakens the bee. The species is a vector for at least five debilitating bee viruses, including RNA viruses such as the deformed wing virus (DWV). The Varroa mite is the parasite with possibly the most pronounced economic impact on the beekeeping industry and is one of multiple stress factors contributing to the higher levels of bee losses around the world. Varroa mite has also been implicated as one of the multiple causes of colony collapse disorder.
Management of this pest focuses on reducing mite numbers through monitoring to avoid significant hive losses or death. 3% of bees infested in a hive is considered an economic threshold where damage is high enough to warrant additional management. Miticides, are available, though some are difficult to time correctly while avoiding harm to the hive, and resistance has occurred for others. Screened bottom boards on hives can be used for both monitoring and mite removal, and drone comb that mites prefer can be used as a trap to remove mites from the hive. Honey bee lines in breeding programs also show partial resistance to Varroa mite through increased hygienic behavior that is being incorporated as an additional management strategy. (Full article...)
Image 3Some of the various hypotheses of myriapod phylogeny. Morphological studies (trees a and b) support a sister grouping of Diplopoda and Pauropoda, while studies of DNA or amino acid similarities suggest a variety of different relationships, including the relationship of Pauropoda and Symphyla in tree c. (from Myriapoda)
Image 11 This fully-grown robber crab has tough fabric forming its joints, delicate biomineralized cuticle over its sensory antennae, optic-quality over its eyes, and strong, calcite-reinforced chitin armouring its body and legs; its pincers can break into coconuts (from Arthropod exoskeleton)
Image 12In honeypot antrepletes, the abdomens of the workers that hold the sugar solution grow vastly, but only the unsclerotised cuticle can stretch, leaving the unstretched sclerites as dark islands on the clear abdomen (from Arthropod exoskeleton)
Image 15Ghost crab, showing a variety of integument types in its exoskeleton, with transparent biomineralization over the eyes, strong biomineralization over the pincers, and tough chitin fabric in the joints and the bristles on the legs (from Arthropod exoskeleton)
Image 16This Zoea-stage larva is hardly recognisable as a crab, but each time it sheds its cuticle it remodels itself, eventually taking on its final crab form (from Arthropod exoskeleton)
Image 18Decapods, from Ernst Haeckel's 1904 work Kunstformen der Natur (from Crustacean)
Image 19Formation of anterior segments across arthropod taxa based on gene expression and neuroanatomical observations, Note the chelicera(Ch) and chelifore(Chf) arose from somite 1 and thus correspond to the first antenna(An/An1) of other arthropods. (from Chelicerata)
Image 22The house centipedeScutigera coleoptrata has rigid sclerites on each body segment. Supple chitin holds the sclerites together and connects the segments flexibly. Similar chitin connects the joints in the legs. Sclerotised tubular leg segments house the leg muscles, their nerves and attachments, leaving room for the passage of blood to and from the hemocoel (from Arthropod exoskeleton)
Image 24Mature queen of a termite colony, showing how the unsclerotised cuticle stretches between the dark sclerites that failed to stretch as the abdomen grew to accommodate her ovaries (from Arthropod exoskeleton)
A European paper wasp (Polistes dominula) heating a bubble of regurgitated fluid in the sunlight. This is a common practice among many winged insects, and it is believed to be a way to facilitate digestion or to cool themselves off.
The orb-weaver spiders (family Araneidae) are the familiar builders of spiral wheel-shaped webs often found in gardens, fields and forests. The family is a large one, including over 2800 species in over 160 genera worldwide, making it the third largest known (behind Salticidae and Linyphiidae). The web has always been thought of as an engineering marvel.
Xylotrupes socrates (Siamese rhinoceros beetle, or "fighting beetle"), male, on a banana leaf. This scarab beetle is particularly known for its role in insect fighting in Northern Laos and Thailand.
The light blue soldier crab (Mictyris longicarpus) inhabits beaches in the Indo-Pacific region. Soldier crabs filter sand or mud for microorganisms. They congregate during the low tide, and bury themselves in a corkscrew pattern during high tide, or whenever they are threatened.
The Polyphemus Moth (Anthera polyphemus) is one the biggest moths, having a wingspan of up to 15 cm. Usually found in forests, moths are notable for apparently being attracted to light, the reason for this behaviour is not known.
The Globe Skimmer (Pantala flavescens) is the most widespread dragonfly species on the planet, found between about the 40th parallels of latitude, or where the annual mean temperature is above 20 °C (68 °F), except in Europe where there are only occasional sightings.
Attacus taprobanis is a species of moth in the family Saturniidae native to southern India and Sri Lanka. This adult male, photographed in Kadavoor, Kerala, developed from a larva feeding on a mahogany tree. When ready to pupate, the larva formed a papery cocoon 7.5 cm (3 in) long interwoven with a leaf; before doing this, the larva had attached the leaf to the stem with a silken thread and cut the leaf stalk. The colours of the dying leaf provided camouflage for the pupa, and the adult insect emerged some 24 days later.
Anthidium florentinum, a species of bee in the family Megachilidae. Bees are flying insects closely related to wasps and ants that are involved in pollination. There are nearly 20,000 known species of bees in seven recognized biological families. Bees are found on every continent except Antarctica, in every habitat on the planet that contains insect-pollinated flowering plants. Bees range in size from tiny stingless bee species whose workers are less than 2 millimetres (0.08 in) long, to Megachile pluto, whose females can attain a length of 39 millimetres (1.54 in).
The European paper wasp (Polistes dominula or Polistes dominulus) is one of the most common species of wasps in the genus Polistes. Originally described in 1791 by German naturalist Johann Ludwig Christ as Vespa dominula, it is native to southern Europe and North Africa, as well as temperate parts of Asia as far east as China. It has also been introduced to Australia, New Zealand, South Africa and the Americas. The species is common and cosmopolitan due to its exceptional survival features, such as a productive colony cycle, a short development time and a higher ability to endure predator attacks. It generally lives in temperate, terrestrial habitats, such as chaparral, forest and grassland biomes.
This picture shows a young European paper wasp queen guarding her nest and eggs.
Zonocerus variegatus, the variegated grasshopper, is a species of grasshopper in the family Pyrgomorphidae native to tropical western and central Africa. It feeds on a wide variety of plant foods and causes damage to crops, particularly cassava, groundnuts and vegetables, as well as transmitting diseases caused by mosaic viruses between plants. This Z. variegatus grasshopper was photographed in the Bobiri Forest in Ghana.
A male Roesel's bush-cricket (Metrioptera roeseli), a European bush-cricket named after August Johann Rösel von Rosenhof, a German entomologist. Its song is very similar to that of Savi's Warbler. Its body length as an adult insect is 15 to 18 mm. It is brown with a pale margin to the sides of the pronotum. Its forewings usually reach midway along its abdomen at rest. However there is a macropterous form of this insect (f. diluta), in which the wings reach beyond the tip of the abdomen. This form appears predominantly during hot summers and enables the species to extend its geographical range rapidly while conditions are suitable; such migrations may also be in response to local overpopulation.
A macro view of a Gonia capitatafly feeding on honey, showing its proboscis and pedipalps (the two appendages protruding from the proboscis), two types of insect mouthparts. The proboscis actually comprises the labium, a quadrupedal structure, and a sponge-like labellum at the end. Flies eat solid food by secreting saliva and dabbing it over the food item. As the saliva dissolves the food, the solution is then drawn up into the mouth as a liquid. The labellum's surface is covered by minute food channels which form a tube leading to the esophagus, and food is drawn up the channels by capillary action.
A Eusthenia species of stonefly. The order contains almost 3,500 known species, including the only known insects that are exclusively aquatic from birth to death. Stoneflies are believed to be one of the most primitive groups of Neoptera and are found worldwide, with the exception of Antarctica.
The Ozyptila praticola species of crab spider is found throughout Europe and the Middle East. They do not build webs to trap prey, but are active hunters. Crab spiders are so named because of their first two pairs of legs, which are held out to the side giving them a crab-like appearance. Also, like crabs, these spiders move sideways and backwards more easily than forwards.
A fishing spider with two of its legs missing. Most likely some predator (a bird, or given its habitat a large fish or frog) grasped the spider by the missing limbs which were jettisoned by the spider in response, a process known as autotomy.
Compound eyes on a blue bottle fly. Unlike simple eyes, which have a single concave photoreceptive surface, compound eyes consist of a number of individual lenses (called ommatidia) laid out on a convex surface; this means that they point in slightly different directions. Compound eyes provide a wide field of view and can detect fast movement, but have low resolution.
Two Eastern Lubber grasshoppers (Romalea guttata) mating. Native to the southeastern and south central portion of the United States, it is well known both for its size and its unique coloration. During reproduction, the male grasshopper introduces sperm into the ovipositor through its aedeagus (reproductive organ), and inserts its spermatophore, a package containing the sperm, into the female's ovipositor.
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