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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Male Maevia inclemens - gray morph
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 genusMaevia. 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...)
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Fossil carapace and portions of the abdomen of R. vaningeni
Rhinocarcinosoma is a genus of eurypterid, an extinct group of aquatic arthropods. Fossils of Rhinocarcinosoma have been discovered in deposits ranging of Late Silurian age in the United States, Canada and Vietnam. The genus contains three species, the American R. cicerops and R. vaningeni and the Vietnamese R. dosonensis. The generic name is derived from the related genus Carcinosoma, and the Greek ῥινός (rhinós, "nose"), referring to the unusual shovel-shaped protrusion on the front of the carapace (head plate) of Rhinocarcinosoma, its most distinctive feature.
Other than the protrusion, Rhinocarcinosoma was anatomically very similar to its close relative, Eusarcana, though it lacked the scorpion-like telson (the posteriormost division of the body) of that genus. Further distinguishing features include more slender appendages and slightly different ornamentation of scales. In terms of size, Rhinocarcinosoma was a medium-sized carcinosomatid eurypterid, with the largest species, R. vaningeni, reaching lengths of 39 centimetres (15.4 in). In contrast to other carcinosomatids, Rhinocarcinosoma is not known only from marine settings, but also from deposits that were once lakes or rivers. It was adapted to a bottom-dwelling lifestyle, as either a burrowing or digging scavenger or top predator, feeding on other invertebrates and small fish. (Full article...)
Butterflies are winged insects from the lepidopteransuborderRhopalocera, characterized by large, often brightly coloured wings that often fold together when at rest, and a conspicuous, fluttering flight. The group comprises the superfamiliesHedyloidea (moth-butterflies in the Americas) and Papilionoidea (all others). The oldest butterfly fossils have been dated to the Paleocene, about 56 million years ago, though they likely originated in the Late Cretaceous, about 101 million years ago.
Butterflies have a four-stage life cycle, and like other holometabolous insects they undergo complete metamorphosis. Winged adults lay eggs on the food plant on which their larvae, known as caterpillars, will feed. The caterpillars grow, sometimes very rapidly, and when fully developed, pupate in a chrysalis. When metamorphosis is complete, the pupal skin splits, the adult insect climbs out, expands its wings to dry, and flies off.
Some butterflies, especially in the tropics, have several generations in a year, while others have a single generation, and a few in cold locations may take several years to pass through their entire life cycle. (Full article...)
Waptia is an extinctgenus of arthropod from the Middle Cambrian of North America. It grew to a length of 6.65 cm (3 in), and had a large bivalved carapace and a segmented body terminating into a pair of tail flaps. It was an active swimmer and likely a predator of soft-bodied prey. It is also one of the oldest animals with direct evidence of brood care. Waptia fieldensis is the only species classified under the genusWaptia, and is known from the Burgess ShaleLagerstätte of British Columbia, Canada. Specimens of Waptia are also known from the Spence Shale of Utah, United States.
Based on the number of individuals, Waptia fieldensis is the third most abundant arthropod from the Burgess Shale Formation, with thousands of specimens collected. It was among the first fossils found by the American paleontologistCharles D. Walcott in 1909. He described it in 1912 and named it after two mountains near the discovery site – Wapta Mountain and Mount Field.
Although it bears a remarkable resemblance to modern crustaceans, its taxonomic affinities were long unclear. A comprehensive redescription published in 2018 classified it a member of Hymenocarina (which contains numerous other bivalved arthropods) within Mandibulata. (Full article...)
Beetles are insects that form the orderColeoptera (/koʊliːˈɒptərə/), in the superorder Holometabola. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 described species, is the largest of all orders, constituting almost 40% of described insects and 25% of all known animal species; new species are discovered frequently, with estimates suggesting that there are between 0.9 and 2.1 million total species. Found in almost every habitat except the sea and the polar regions, they interact with their ecosystems in several ways: beetles often feed on plants and fungi, break down animal and plant debris, and eat other invertebrates. Some species are serious agricultural pests, such as the Colorado potato beetle, while others such as Coccinellidae (ladybirds or ladybugs) eat aphids, scale insects, thrips, and other plant-sucking insects that damage crops. Some others also have unique characteristics, such as the common eastern firefly, which uses a light-emitting organ for mating and communication purposes
Beetles typically have a particularly hard exoskeleton including the elytra, though some such as the rove beetles have very short elytra while blister beetles have softer elytra. The general anatomy of a beetle is quite uniform and typical of insects, although there are several examples of novelty, such as adaptations in water beetles which trap air bubbles under the elytra for use while diving. Beetles are holometabolans, which means that they undergo complete metamorphosis, with a series of conspicuous and relatively abrupt changes in body structure between hatching and becoming adult after a relatively immobile pupal stage. Some, such as stag beetles, have a marked sexual dimorphism, the males possessing enormously enlarged mandibles which they use to fight other males. Many beetles are aposematic, with bright colors and patterns warning of their toxicity, while others are harmless Batesian mimics of such insects. Many beetles, including those that live in sandy places, have effective camouflage.
Eucteniza (/juːktəˈnaɪzə/yook-tə-NY-zə) is a genus of trapdoor spiders in the family Euctenizidae containing at least 14 species occurring in Mexico and the southern United States. Species are distinguished by a softened rear portion of the carapace, and males possess large spines on the first two pairs of walking legs that are used to hold females during mating. Like other trapdoor spiders they create burrows with a hinged lid, from which they await passing insects and other arthropods to prey upon. Many species are known from only one or two localities, or from only male specimens. More species are expected to be discovered. Eucteniza is closely related to spiders of the genera Entychides and Neoapachella. (Full article...)
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Fossil specimen (holotype) on display at the Smithsonian in Washington, D.C.
Opabinia regalis is an extinct, stem grouparthropod found in the Middle CambrianBurgess ShaleLagerstätte (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...)
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Andreacarus voalavo is a parasiticmite found on the Malagasy rodent Voalavo gymnocaudus. First described in 2007, it is closely related to Andreacarus gymnuromys and Andreacarus eliurus, which are found on other Malagasy rodents. The length of the idiosoma, the main body, is 630 to 670 μm in females and 450 to 480 μm in males. Unlike A. eliurus, this species lacks distinct sternal glands (secretory organs) between two lyrifissures (sensory organs) on the lower part of the female body. The pilus dentilis, a sensory organ on the chelicera, is serrate, which distinguishes it from A. gymnuromys. Females of A. gymnuromys also have a less ornamented sternal shield (covering part of the underparts) and shorter setae (bristles) on the upperparts. (Full article...)
Parasitoid wasp species differ in which host life-stage they attack: eggs, larvae, pupae, or adults. They mainly follow one of two major strategies within parasitism: either they are endoparasitic, developing inside the host, and koinobiont, allowing the host to continue to feed, develop, and moult; or they are ectoparasitic, developing outside the host, and idiobiont, paralysing the host immediately. Some endoparasitic wasps of the superfamily Ichneumonoidea have a mutualistic relationship with polydnaviruses, the viruses suppressing the host's immune defenses.
Parasitoidism evolved only once in the Hymenoptera, during the Permian, leading to a single clade called Euhymenoptera, but the parasitic lifestyle has secondarily been lost several times including among the ants, bees, and vespid wasps. As a result, the order Hymenoptera contains many families of parasitoids, intermixed with non-parasitoid groups. The parasitoid wasps include some very large groups, some estimates giving the Chalcidoidea as many as 500,000 species, the Ichneumonidae 100,000 species, and the Braconidae up to 50,000 species. Host insects have evolved a range of defences against parasitoid wasps, including hiding, wriggling, and camouflage markings. (Full article...)
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Y. geinitzi worker
Yantaromyrmex is an extinctgenus of ants first described in 2013. Members of this genus are in the subfamily Dolichoderinae of the family Formicidae, known from Middle Eocene to Early Oligocene fossils found in Europe. The genus currently contains five described species, Y. constrictus, Y. geinitzi, Y. intermedius, Y. mayrianum and Y. samlandicus. The first specimens were collected in 1868 and studied by Austrian entomologist Gustav Mayr, who originally placed the fossils in other ant genera until the fossils were reviewed and subsequently placed into their own genus. These ants are small, measuring from 4 to 6 mm (0.16 to 0.24 in) in length and can be characterized by their trapezoidal shaped head-capsules and oval compound eyes that are located slightly to the rear of the capsules midpoint, with no known ocelli present. (Full article...)
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N. ensifer worker specimen
Novomessor ensifer is a species of ant endemic to Mexico. A member of the genus Novomessor in the subfamily Myrmicinae, it was first described by Swiss entomologist Auguste Forel in 1899. N. ensifer was originally a part of the genus Aphaenogaster until a recent phylogenetic study concluded that Novomessor was genetically distinct and should be separated. The ant is a medium-sized species, measuring 5.5 to 10 millimetres (0.2 to 0.4 in). The ant is ferruginous-colored in some certain parts of the body, and small workers (nanitics) in incipient colonies are noticeably different in color and body structure.
N. ensifer is active throughout the day, where they forage on the ground and sometimes on low herbs. Colonies are found under stones and other objects in tropical dry forests and pine-oak forests. These ants are solitary foragers and predominantly feed on insects such as wasps and moths. The only known predator of N. ensifer is the giant horned lizard (Phrynosoma asio). While nothing is known about its reproduction, nuptial flight may take place during spring or summer, where queens establish their nests under stones and other objects. (Full article...)
Mole crickets are members of the insect familyGryllotalpidae, in the orderOrthoptera (grasshoppers, locusts, and crickets). Mole crickets are cylindrical-bodied, fossorialinsects about 3–5 cm (1.2–2.0 in) long as adults, with small eyes and shovel-like fore limbs highly developed for burrowing. They are present in many parts of the world and where they have arrived in new regions, may become agricultural pests.
Mole crickets have three life stages: eggs, nymphs, and adults. Most of their lives in these stages are spent underground, but adults have wings and disperse in the breeding season. They vary in their diet: some species are herbivores, mainly feeding on roots; others are omnivores, including worms and grubs in their diet; and a few are largely predatory. Male mole crickets have an exceptionally loud song; they sing from a burrow that opens out into the air in the shape of an exponential horn. The song is an almost pure tone, modulated into chirps. It is used to attract females, either for mating, or for indicating favourable habitats for them to lay their eggs.
In Zambia, mole crickets are thought to bring good fortune, while in Latin America, they are said to predict rain. In Florida, where Neoscapteriscus mole crickets are not native, they are considered pests, and various biological controls have been used. Gryllotalpa species have been used as food in West Java, Vietnam, Thailand, Laos, and the Philippines. (Full article...)
Carcinosomatidae (the name deriving from the type genusCarcinosoma, meaning "crab body") is a family of eurypterids, an extinct group of aquatic arthropods. They were members of the superfamily Carcinosomatoidea, also named after Carcinosoma. Fossils of carcinosomatids have been found in North America, Europe and Asia, the family possibly having achieved a worldwide distribution, and range in age from the Late Ordovician to the Early Devonian. They were among the most marine eurypterids, known almost entirely from marine environments.
Carcinosomatids varied considerably in size, from species only a few centimetres in length to some of the largest known arthropods. The largest carcinosomatid species, Carcinosoma punctatum, reached lengths of at least 2.2 metres (7.2 ft) and rivalled the largest eurypterid of all, Jaekelopterus, in size. Morphologically, carcinosomatids were highly distinct from other eurypterids, known for their powerful and spiny set of forelimbs, a broad and rounded central body and a slender and tubular tail ending in a telson (the posteriormost division of the body) that was typically curved in some way. With these adaptations, the carcinosomatids were quite similar to scorpions, and the group may have helped contribute to the common name of eurypterids becoming 'sea scorpions'. The family contains four, possibly five, genera: Carcinosoma, Eocarcinosoma, Eusarcana, Rhinocarcinosoma and possibly the problematic genus Holmipterus.
It is unlikely that the carcinosomatids were strong and active swimmers, given their non-streamlined shape. It is more probable that they were nektobenthic (swimming near the bottom), possibly being top predators (given their size) or scavengers, digging for food or perhaps even burrowing and lying in wait as ambush predators. (Full article...)
... that Edward L. Kessel assembled the world's most comprehensive collection of Platypezidae flat-footed flies?
... that in the north, the North American paper waspPolistes annularis has rust-red markings on a predominantly black thorax, but in the south, the thorax is mostly rust-red with black markings?
Image 4The 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 5Reconstruction of Mollisonia plenovenatrix, the oldest known arthropod with confirmed chelicerae (from Chelicerata)
Image 7 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 22Formation 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 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)
Image 25Some 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 26The fangs in spiders' chelicerae are so sclerotised as to be greatly hardened and darkened (from Arthropod exoskeleton)
Image 31In 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 32This 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 33Ghost 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)
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.
The Adonis blue (Polyommatus bellargus) is a butterfly in the family Lycaenidae, found in Europe and parts of West Asia. This photograph, taken in a chalk meadow at Yoesden Bank in Buckinghamshire, England, shows the underside of the folded wings of a male Adonis blue; the upper side is a bright, sky-blue.
A mole cricket, an insect belonging to the Gryllotalpidaefamily. Mole crickets are common insects, found on every continent except Antarctica, but because they are nocturnal and spend nearly all their lives underground in extensive tunnel systems, they are rarely seen. This specimen is likely to be Gryllotalpa brachyptera and is about 3.5 cm (1.4 in.) in size.
The head of a female Clynotis severus species of jumping spider. The eyes of a spider are called simple eyes (as opposed to compound eyes) because in each eye, a single lens collects and focuses light onto the retina. In this spider, the two largest eyes in the middle are the most acute. The remainder on the sides and on the top of its head are "secondary eyes".
Two flesh-flies (Sarcophaga ruficornis species pictured) mating. The life cycle of the saprophagic flesh-fly larvae has been well researched and is very predictable. Different species prefer bodies in different states of decomposition, which allows forensic entomologists to extrapolate the time of death.
The western honey bee (Apis mellifera) is the most common of the 7–12 species of honey bee worldwide. It is believed to have originated in either Africa or Asia, and spread naturally through Africa, the Middle East and Europe. Following human introduction into the Americas and Oceania, the species is now found on every continent except Antarctica. Humans have been collecting honey from bees for thousands of years, with evidence in the form of rock art found in France and Spain, dating to around 7000 BC. Along with other insects, the honey bee is an important pollinator, with a large number of the crop species farmed worldwide depending on it.
The longtail tadpole shrimp (Triops longicaudatus) is a freshwater crustacean resembling a miniature horseshoe crab. It is one of the oldest animal species still in existence. Like its relative Triops cancriformis, the longtail tadpole shrimp is considered a living fossil because its basic prehistoric morphology has changed little in the last 70 million years, exactly matching ancient fossils.
The oriental hornet (Vespa orientalis) is a social insect in the family Vespidae, found in southern Europe, northeastern Africa, and western Asia. This worker, photographed in Sha'ar Poleg Reserve in Israel, is gathering nectar from a sea squill; adults will also feed on honeydew and fruit. They also capture insects such as grasshoppers, flies and honey bees to provide a diet high in protein for the colony's brood.
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.
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.
Purana tigrina is a species of cicada found in Southeast Asia. This adult male was photographed in Kadavoor, Kerala, in southern India, and is about one inch (25 mm) in length. The mouthparts are adapted to piercing plant tissues and sucking sap; the male abdomen houses the tymbal, an organ used in the production of song, while the female abdomen is tipped by a large, saw-edged ovipositor.
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.
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 red rock crab (Grapsus grapsus), also known as "Sally Lightfoot", is one of the commonest crabs along the western seaboard of the Americas. John Steinbeck wrote of them, "Everyone who has seen them has been delighted with them ... These little crabs, with brilliant cloisonné carapaces, walk on their tiptoes, they have remarkable eyes and an extremely fast reaction time." He tried to catch them but to little avail. "If you walk slowly, they move slowly ahead of you in droves. If you hurry, they hurry. When you plunge at them, they seem to disappear in a puff of blue smoke."
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.
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.
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