Portal:Arthropods

Maevia inclemens or the dimorphic jumping spider is a relatively common and colorful jumping spider of North America. In the males there are two forms, a very rare phenomenon in zoology. These use different courting displays, and differ in appearance: the "tufted" morph has a black body and pedipalps ("palps"), three black tufts across its "head", and pale legs; and the "gray" morph has black and white stripes all over its body and legs, orange palps, and no tufts. However, each form accounts for 50% of the adult males, and they are equally successful in mating. A female of Maevia inclemens is 6.5 to 8.0 millimetres (0.26 to 0.31 in) long, while males are 4.75 to 6.50 millimetres (0.187 to 0.256 in) long.

Like all jumping spiders, M. inclemens has excellent vision. The main eyes, in the front-and-center position, are large, and are more acute than those of a cat and about 10 times as acute as a dragonfly's. The remaining three pairs of eyes are along the sides of the head, and work as motion detectors. The eyes are used for hunting, for avoiding threats and for finding mates.

Maevia inclemens is one of the eight species in genus Maevia. The species was first called Attus inclemens, and other names have been used. The two male forms look and behave so differently that they were originally considered two distinct species. In 1955 Robert Barnes chose M. inclemens, and this has become the standard name. (Full article...)

Lictor mirabilis is a species of jumping spider in the genus Lictor that lives in the forests of Nigeria. The species was first described in 2011 by Wanda Wesołowska and Russell-Smith. Initially allocated to the genus Thiratoscirtus, the species was moved to its current genus in 2023. The spider is small, with an ovoid cephalothorax that is between 3.3 and 4.1 mm (0.13 and 0.16 in) long and a longer, thinner abdomen that is between 2.9 and 5.1 mm (0.11 and 0.20 in) long. The spider's carapace, the hard upper part of the cephalothorax, has a clear depression, or fovea, in the middle. The male has generally brown legs while the female's legs are brownish yellow. It can be distinguished from other species in the genus by its unusual copulatory organs. The male has an anvil-shaped protrusion, or apophysis, on its palpal tibia. The female has large translucent cup-like features near the front of its large epigyne and long insemination ducts. The unusual nature of its copulatory organs is recalled in its species name, which is a Latin word that can be translated as "strange". (Full article...)

The California spiny lobster (Panulirus interruptus) is a species of spiny lobster found in the eastern Pacific Ocean from Monterey Bay, California, to the Gulf of Tehuantepec, Mexico. It typically grows to a length of 30 cm (12 in) and is a reddish-brown color with stripes along the legs, and has a pair of enlarged antennae but no claws. The interrupted grooves across the tail are characteristic for the species.

Females can carry up to 680,000 eggs, which hatch after 10 weeks into flat phyllosoma larvae. These feed on plankton before the metamorphosis into the juvenile state. Adults are nocturnal and migratory, living among rocks at depths of up to 65 m (213 ft), and feeding on sea urchins, clams, mussels and worms. The spiny lobster is eaten by various fish, octopuses and sea otters, but can defend itself with a loud noise produced by its antennae. The California spiny lobster is the subject of both commercial and recreational fishery in both Mexico and the United States, with sport fishermen using hoop nets and commercial fishermen using lobster traps. (Full article...)

The deathwatch beetle (Xestobium rufovillosum) is a species of woodboring beetle that sometimes infests the structural timbers of old buildings. The adult beetle is brown and measures on average 7 mm (0.3 in) long. Eggs are laid in dark crevices in old wood inside buildings, trees, and inside tunnels left behind by previous larvae. The larvae bore into the timber, feeding for up to ten years before pupating, and later emerging from the wood as adult beetles. Timber that has been damp and is affected by fungal decay is soft enough for the larvae to chew through. They obtain nourishment by using enzymes present in their gut to digest the cellulose and hemicellulose in the wood.

The larvae of deathwatch beetles weaken the structural timbers of a building by tunneling through them. Treatment with insecticides to kill the larvae is largely ineffective, and killing the adult beetles when they emerge in spring and early summer may be a better option. However, infestation by these beetles is often limited to historic buildings, because modern buildings tend to use softwoods for joists and rafters instead of aged oak timbers, which the beetles prefer.

To attract mates, the adult insects create a tapping or ticking sound that can sometimes be heard in the rafters of old buildings on summer nights; therefore, the deathwatch beetle is associated with quiet, sleepless nights and is named for the vigil (watch) being kept beside the dying or dead. By extension, there exists a superstition that these sounds are an omen of impending death. (Full article...)

The jack jumper ant (Myrmecia pilosula), also known as the jack jumper, jumping jack, hopper ant, or jumper ant, is a species of venomous ant native to Australia. Most frequently found in Tasmania and southeast mainland Australia, it is a member of the genus Myrmecia, subfamily Myrmeciinae, and was formally described and named by British entomologist Frederick Smith in 1858. This species is known for its ability to jump long distances. These ants are large; workers and males are about the same size: 12 to 14 mm (0.47 to 0.55 in) for workers, and 11 to 12 mm (0.43 to 0.47 in) for males. The queen measures roughly 14 to 16 mm (0.55 to 0.63 in) long and is similar in appearance to workers, whereas males are identifiable by their perceptibly smaller mandibles.

Jack jumper ants are primarily active during the day and live in open habitats, nesting in bushland, woodlands, and dry open forests, surrounded by gravel and sandy soil, which can be found in rural areas and are less common in urban areas. They prey on small insects and use their barbless stingers to kill other insects by injecting venom. Other ants and predatory invertebrates prey on the jack jumper ant. The average worker has a life expectancy of over one year. Workers are gamergates, allowing them to reproduce with drones, whether or not a queen is present in the colony. The ant is a part of the Myrmecia pilosula species complex; this ant and other members of the complex are known to have a single pair of chromosomes.

Their sting generally only causes a mild local reaction in humans; however, it is one of the few ant species that can be dangerous to humans, along with other ants in the genus Myrmecia. The ant venom is particularly immunogenic for an insect venom; the venom causes about 90% of Australian ant allergies. In endemic areas, up to 3% of the human population has developed an allergy to the venom and about half of these allergic people can suffer from anaphylactic reactions (increased heart rate, falling blood pressure, and other symptoms), which can lead to death on rare occasions. Between 1980 and 2000, four deaths were due to anaphylaxis from jack jumper stings, all of them in Tasmania. Individuals prone to severe allergic reactions caused by the ant's sting can be treated with allergen immunotherapy (desensitisation). (Full article...)

Slimonidae (the name deriving from the type genus Slimonia, which is named in honor of Welsh fossil collector and surgeon Robert Slimon) is a family of eurypterids, an extinct group of aquatic arthropods. Slimonids were members of the superfamily Pterygotioidea and the family most closely related to the derived pterygotid eurypterids, which are famous for their cheliceral claws and great size. Many characteristics of the Slimonidae, such as their flattened and expanded telsons (the posteriormost division of their bodies), support a close relationship between the two groups.

Slimonids are defined as pterygotioid eurypterids with swimming legs similar to those of the type genus, Slimonia, and the second to fifth pair of appendages being non-spiniferous. The family contains only two genera, the almost completely known Slimonia and Salteropterus, which is known only from the telson and the metastoma (a large plate part of the abdomen).

Both slimonid genera preserve flattened and expanded telsons that end in elongated telson spikes. The discovery of several articulated specimens of Slimonia with the tail segments preserved in tight curves, suggesting that the tail segments were considerably more flexible than previously thought and would have been capable of considerable side-to-side movement. Unlike the related pterygotids, the slimonids did not possess robust and powerful cheliceral claws and as such, these telson spikes may have been the primary weaponry used by Slimonia, although this theory is considered unlikely by contemporary researchers. The telson spike of Salteropterus was likely not used as a weapon and was highly distinct and different from that of any other eurypterid. (Full article...)

Drosophila subobscura is a species of fruit fly in the family Drosophilidae. Originally found around the Mediterranean, it has spread to most of Europe and the Near East. It has been introduced into the west coasts of Canada, the United States, and Chile. Its closest relative is Drosophila madeirensis, found in the Madeira Islands, followed by D. guanche, found in the Canary Islands. These three species form the D. subobscura species subgroup. When they mate, males and females perform an elaborate courtship dance, in which the female can either turn away to end the mating ritual, or stick out her proboscis in response to the male's, allowing copulation to proceed. D. subobscura has been regarded as a model organism for its use in evolutionary-biological studies. (Full article...)

Phengaris rebeli (formerly Maculinea rebeli), common name mountain Alcon blue, is a species of butterfly in the family Lycaenidae. It was first found and described in Styria, Austria, on Mount Hochschwab around 1700. Although it was initially classified as a subspecies of P. alcon, a European researcher, Lucien A. Berger, designated it as a separate species in 1946. Genetic similarities between P. rebeli and P. alcon have led many researchers to argue that the two are the same species and differences are due to intraspecific variation.

Although P. rebeli is found across the Palearctic (see subspecies), it is difficult to determine the species' precise range due to confusion with P. alcon.

Behavioral ecologists have found its role as a brood parasite to be of particular interest as, unlike many brood parasites, it does not directly oviposit in the hosts' nests. P. rebeli parasitizes the colony ant species Myrmica schencki as a larva by using chemical mimicry to trick the ants into believing that they are ant larvae; thus, the ants bring P. rebeli caterpillars back to their nests and feed them. P. rebeli is dependent on the plant Gentiana cruciata early in its life cycle and is vulnerable to parasitism by Ichneumon eumerus while inside the nest of M. schencki. It was placed on the IUCN Red List in 2000 and is classified as a species vulnerable to extinction. (Full article...)

Termites are a group of detritophagous eusocial insects which consume a variety of decaying plant material, generally in the form of wood, leaf litter, and soil humus. They are distinguished by their moniliform antennae and the soft-bodied and often unpigmented worker caste for which they have been commonly termed "white ants"; however, they are not ants, to which they are only distantly related. About 2,972 extant species are currently described, 2,105 of which are members of the family Termitidae.

Termites comprise the infraorder Isoptera, or alternatively the epifamily Termitoidae, within the order Blattodea (along with cockroaches). Termites were once classified in a separate order from cockroaches, but recent phylogenetic studies indicate that they evolved from cockroaches, as they are deeply nested within the group, and the sister group to wood eating cockroaches of the genus Cryptocercus. Previous estimates suggested the divergence took place during the Jurassic or Triassic. More recent estimates suggest that they have an origin during the Late Jurassic, with the first fossil records in the Early Cretaceous.

Similarly to ants and some bees and wasps from the separate order Hymenoptera, most termites have an analogous "worker" and "soldier" caste system consisting of mostly sterile individuals which are physically and behaviorally distinct. Unlike ants, most colonies begin from sexually mature individuals known as the "king" and "queen" that together form a lifelong monogamous pair. Also unlike ants, which undergo a complete metamorphosis, termites undergo an incomplete metamorphosis that proceeds through egg, nymph, and adult stages. Termite colonies are commonly described as superorganisms due to the collective behaviors of the individuals which form a self-governing entity: the colony itself. Their colonies range in size from a few hundred individuals to enormous societies with several million individuals. Most species are rarely seen, having a cryptic life-history where they remain hidden within the galleries and tunnels of their nests for most of their lives. (Full article...)

Homarus gammarus, known as the European lobster or common lobster, is a species of clawed lobster from the eastern Atlantic Ocean, Mediterranean Sea and parts of the Black Sea. It is closely related to the American lobster, H. americanus. It may grow to a length of 60 cm (24 in) and a mass of 6 kilograms (13 lb), and bears a conspicuous pair of claws. In life, the lobsters are blue, only becoming "lobster red" on cooking. Mating occurs in the summer, producing eggs which are carried by the females for up to a year before hatching into planktonic larvae. Homarus gammarus is a highly esteemed food, and is widely caught using lobster pots, mostly around the British Isles. (Full article...)

Aphids are small sap-sucking insects and members of the superfamily Aphidoidea. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white woolly aphids. A typical life cycle involves flightless females giving live birth to female nymphs—who may also be already pregnant, an adaptation scientists call telescoping generations—without the involvement of males. Maturing rapidly, females breed profusely so that the number of these insects multiplies quickly. Winged females may develop later in the season, allowing the insects to colonize new plants. In temperate regions, a phase of sexual reproduction occurs in the autumn, with the insects often overwintering as eggs.

The life cycle of some species involves an alternation between two species of host plants, for example between an annual crop and a woody plant. Some species feed on only one type of plant, while others are generalists, colonizing many plant groups. About 5,000 species of aphid have been described, all included in the family Aphididae. Around 400 of these are found on food and fiber crops, and many are serious pests of agriculture and forestry, as well as an annoyance for gardeners. So-called dairying ants have a mutualistic relationship with aphids, tending them for their honeydew and protecting them from predators.

Aphids are among the most destructive insect pests on cultivated plants in temperate regions. In addition to weakening the plant by sucking sap, they act as vectors for plant viruses and disfigure ornamental plants with deposits of honeydew and the subsequent growth of sooty moulds. Because of their ability to rapidly increase in numbers by asexual reproduction and telescopic development, they are a highly successful group of organisms from an ecological standpoint. (Full article...)

Wanda Wesołowska (born 11 August 1950) is a Polish zoologist known for her work with jumping spiders. She has described more species of jumping spider than any contemporary writer, and is second only to Eugène Simon in the history of arachnology. Originally a student of ornithology, she developed an interest in jumping spiders while still a student at the Siedlce University of Natural Sciences and Humanities in the 1970s.

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...)

Opabinia regalis is an extinct, stem group arthropod found in the Middle Cambrian Burgess Shale Lagerstätte (505 million years ago) of British Columbia. Opabinia was a soft-bodied animal, measuring up to 7 cm in body length, and its segmented trunk had flaps along the sides and a fan-shaped tail. The head shows unusual features: five eyes, a mouth under the head and facing backwards, and a clawed proboscis that probably passed food to the mouth. Opabinia probably lived on the seafloor, using the proboscis to seek out small, soft food. Fewer than twenty good specimens have been described; 3 specimens of Opabinia are known from the Greater Phyllopod bed, where they constitute less than 0.1% of the community.

When the first thorough examination of Opabinia in 1975 revealed its unusual features, it was thought to be unrelated to any known phylum, or perhaps a relative of arthropod and annelid ancestors. However, later studies since late 1990s consistently support its affinity as a member of basal arthropods, alongside the closely related radiodonts (Anomalocaris and relatives) and gilled lobopodians (Kerygmachela and Pambdelurion).

In the 1970s, there was an ongoing debate about whether multi-celled animals appeared suddenly during the Early Cambrian, in an event called the Cambrian explosion, or had arisen earlier but without leaving fossils. At first Opabinia was regarded as strong evidence for the "explosive" hypothesis. Later the discovery of a whole series of similar lobopodian animals, some with closer resemblances to arthropods, and the development of the idea of stem groups, suggested that the Early Cambrian was a time of relatively fast evolution, but one that could be understood without assuming any unique evolutionary processes. (Full article...)

The purple shore crab (Hemigrapsus nudus or the naked shore crab) is a common crab of the family Varunidae that is indigenous to the west coast of United States, Canada, and Mexico. H. nudus was first described in 1847 by Adam White, and in 1851, James Dwight Dana formally classified the species. H. nudus is a small, amphibious crab that is similar physically and behaviorally to Pachygrapsus crassipes and Hemigrapsus oregonensis. The purple shore crab is generally a dark purple color with olive green, red, and white spots. Mating season for H. nudus begins in mid-winter and larval crabs undergo 5 zoeal stages and a juvenile stage. Adult crabs mainly feed on algae but will occasionally scavenge other animals. H. nudus prefers inter-tidal and sub-tidal zones, and it can oftentimes be found sheltering under rocks or other debris. H. nudus demonstrates complex compensatory mechanisms to counteract fluctuating salinity and water oxygen concentrations, permitting it to live in a variety of different environments. (Full article...)

Terropterus is a genus of eurypterid, an extinct group of aquatic arthropods. The type and only species of Terropterus, T. xiushanensis, is known from deposits of Early Silurian age in China.

Terropterus was the earliest known and largest mixopterid eurypterid. Fossil specimens referred to T. xiushanensis are estimated to have reached up to 40 centimeters (15.7 in) in length, but other fossils, either representing older T. xiushanensis or a second species of Terropterus, demonstrate that members of the genus could reach upwards of at least 100 centimeters (3.3 ft) in length. Terropterus is the only mixopterid known from the ancient southern continent of Gondwana, with the other two mixopterid genera, Mixopterus and Lanarkopterus, only being known from what was once the northern continent of Laurussia. The discovery of Terropterus significantly expanded the known geographical and temporal ranges of the Mixopteridae.

The deposits in which fossils of Terropterus were discovered were once a marine environment. Fossils of several other groups are known from the same deposits, including trilobites, brachiopods, gastropods and other eurypterids. Due to its large size and its predatory adaptations, including the characteristic mixopterid large and spiny forward-facing appendages, Terropterus was likely the apex predator of its marine ecosystem. (Full article...)