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...)
Insect wings are adult outgrowths of the insectexoskeleton that enable insects to fly. They are found on the second and third thoracic segments (the mesothorax and metathorax), and the two pairs are often referred to as the forewings and hindwings, respectively, though a few insects lack hindwings, even rudiments. The wings are strengthened by a number of longitudinal veins, which often have cross-connections that form closed "cells" in the membrane (extreme examples include the dragonflies and lacewings). The patterns resulting from the fusion and cross-connection of the wing veins are often diagnostic for different evolutionary lineages and can be used for identification to the family or even genus level in many orders of insects.
Physically, some insects move their flight muscles directly, others indirectly. In insects with direct flight, the wing muscles directly attach to the wing base, so that a small downward movement of the wing base lifts the wing itself upward. Those insects with indirect flight have muscles that attach to and deform the thorax, causing the wings to move as well.
The wings are present in only one sex (often the male) in some groups such as velvet ants and Strepsiptera, or are selectively lost in "workers" of social insects such as ants and termites. Rarely, the female is winged but the male not, as in fig wasps. In some cases, wings are produced only at particular times in the life cycle, such as in the dispersal phase of aphids. Wing structure and colouration often vary with morphs, such as in the aphids, migratory phases of locusts and polymorphic butterflies. At rest, the wings may be held flat, or folded a number of times along specific patterns; most typically, it is the hindwings which are folded, but in a few groups such as the vespid wasps, it is the forewings. (Full article...)
The moth has lime-green wings and a white body. Its caterpillars are also green. Its typical wingspan is roughly 114 mm (4.5 in), but wingspans can exceed 178 mm (7.0 in), ranking the species as one of the larger moths in North America.
Across Canada, it has one generation per year, with the winged adults appearing in late May or early June, whereas farther south it will have two or even three generations per year, the first appearance as early as March in southern parts of the United States. (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...)
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...)
Erettopterus is a genus of large predatory eurypterid, an extinct group of aquatic arthropods. Fossils of Erettopterus have been discovered in deposits ranging from Early Silurian (the Rhuddanian age) to the Early Devonian (the Lochkovian age), and have been referred to several different species. Fossils have been recovered from two continents; Europe and North America. The genus name is composed by the Ancient Greek words ἐρέττω (eréttō), which means "rower", and πτερόν (pterón), which means "wing", and therefore, "rower wing".
Erettopterus is classified as part of the eurypterid family Pterygotidae, a family differentiated from other eurypterids by their flattened telsons (the most posterior segment of the body) and their modified chelicerae (frontal appendages), ending in well-developed chelae (claws). Although some pterygotid eurypterids, such as Jaekelopterus or Acutiramus grew to gigantic proportions, it is estimated that the largest species of Erettopterus, E. osiliensis, reached 90 cm (35 in). Erettopterus had a bilobed (divided into two lobes) telson, which is its main characteristic. The forms of chelicerae are very diverse between species, but they are generally very long with small curved teeth without serrations.
Studies on the chelicerae and compound eyes of Erettopterus have revealed that it was a predator with high visual acuity, but it was not as highly specialized or active as Jaekelopterus and Pterygotus, it was more like Slimonia acuminata, and probably used its enlarged chelicerae for grasping rather than a more specialized feeding. (Full article...)
H. reaumuri occurs at great population densities and fills an important niche in the desert ecosystem. It feeds on plant leaves, obtains most of its water from moisture in the air and sand, and is in turn an important prey item for the scorpionScorpio maurus. H. reaumuri is only able to survive in such arid conditions because it has developed parental care of its offspring. Adults dig burrows which are inhabited by family groups, which are recognised using pheromones. The burrows are 40–50 cm (16–20 in) deep, and the woodlice retreat to the relatively cool and moist conditions of the burrow when surface conditions are unfavourable. The territorial limit of each colony is marked with a faecal embankment. (Full article...)
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Eusociality (Greek εὖ eu "good" and social) is the highest level of organization of sociality. It is defined by the following characteristics: cooperative brood care (including care of offspring from other individuals), overlapping generations within a colony of adults, and a division of labor into reproductive and non-reproductive groups. The division of labor creates specialized behavioral groups within an animal society which are sometimes referred to as 'castes'. Eusociality is distinguished from all other social systems because individuals of at least one caste usually lose the ability to perform behaviors characteristic of individuals in another caste. Eusocial colonies can be viewed as superorganisms.
Eusociality has evolved among the insects, crustaceans, and mammals. It is most widespread in the Hymenoptera (ants, bees, and wasps) and in Blattodea (termites). A colony has caste differences: queens and reproductivemales take the roles of the sole reproducers, while soldiers and workers work together to create and maintain a living situation favorable for the brood. Queens produce multiple queen pheromones to create and maintain the eusocial state in their colonies; they may also eat eggs laid by other females or exert dominance by fighting. There are two eusocial rodents: the naked mole-rat and the Damaraland mole-rat. Some shrimps, such as Synalpheus regalis, are eusocial. E. O. Wilson and others have made the claim that humans have evolved a weak form of eusociality. It has been suggested that the colonial and epiphytic staghorn fern, too, may make use of a primitively eusocial division of labor. (Full article...)
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The Colorado potato beetle (Leptinotarsa decemlineata) is also known as the Colorado beetle, the ten-striped spearman, the ten-lined potato beetle, or the potato bug. It is a major pest of potato crops. It is about 10 mm (3⁄8 in) long, with a bright yellow/orange body and five bold brown stripes along the length of each of its elytra. Native to the Rocky Mountains, it spread rapidly in potato crops across America and then Europe from 1859 onwards.
Illustration of the carapace of E. batrachophthalmus
Eocarcinosoma is a genus of eurypterid, an extinct group of aquatic arthropods. The type and only species of Eocarcinosoma, E. batrachophthalmus, is known from deposits of Late Ordovician age in the United States. The generic name is derived from the related genus Carcinosoma, and the Greek eós (ἠώς) meaning 'dawn', referring to the earlier age of the genus compared to other carcinosomatid eurypterids.
Eocarcinosoma is known only from a single specimen, a well-preserved small prosoma (head). In life it would have been a very small eurypterid, given that the head measures just 2.05 centimetres (0.8 in) in length. The main distinguishing features from other carcinosomatids were the eyes being placed on the margins of the carapace (head plate) and the head being more triangular in shape than in its later relatives. Although initially believed to be an adult given the relatively small size of the eyes, some researchers believe Eocarcinosoma to represent a juvenile specimen of the eurypterid Megalograptus. (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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Artist's image
Hemigrapsus estellinensis is an extinctspecies of crab, formerly endemic to the Texas Panhandle. It was discovered by Gordon C. Creel in 1962 and was probably already extinct before his description was published in 1964, after the Estelline Salt Springs where it lived were contained by the United States Army Corps of Engineers. H. estellinensis is closely related to species from the Pacific Ocean such as Hemigrapsus oregonensis, but lived 800 km (500 mi) inland in a hypersaline spring. It differed from its relatives by the pattern of spots on its back, and by the relative sizes of its limbs. (Full article...)
Ochetellus is a genus of ants first described by Steve Shattuck in 1992. He placed it in the subfamily Dolichoderinae of the family Formicidae. The ants in this genus are small and black in colour; workers measure 1.75 to 3 millimetres (0.07 to 0.12 in) in length, the males at around 1.6 millimetres (0.06 in) are smaller, and the queens are the largest, reaching 4 millimetres (0.16 in). There are seven described species and three described subspecies that mostly live in Australia in a wide variety of habitats, but some species are found in Asia. One species, Ochetellus glaber, has been introduced into New Zealand and the United States.
The colonies are found in rotten wood, in the ground, under rocks or stones and in urban areas. The ants are both diurnal and nocturnal and forage on trees, in low vegetation and into human homes, where they are regarded as pests. These ants eat a variety of foods, including fruits, insects, sucrose, nectar and bird feces. They visit various flowers and attend to a variety of butterfly larvae. The thorny devil, an Australian lizard, predominantly feeds on Ochetellus workers, and other ant species also prey on them. (Full article...)
Pholcus phalangioides, commonly known as the cosmopolitan cellar spider, long-bodied cellar spider or one of various types called a daddy long-legs spider, is a spider of the family Pholcidae. It is also known as the skull spider, since its cephalothorax is said to resemble a human skull. This is the only spider species described by the Swiss entomologistJohann Kaspar Füssli, who first recorded it in 1775. Its common name of "daddy long-legs" should not be confused with a different arachnid group with the same common name, the harvestman (Opiliones), or the crane flies of the superfamily Tipuloidea.
Females have a body length of about 8 mm while males tend to be slightly smaller. The length of the spider's legs are on average 5 or 6 times the length of its body. Pholcus phalangioides has a habit of living on the ceilings of rooms, caves, garages or cellars.
This spider species is considered beneficial in parts of the world because it preys on other spiders, including species considered dangerous such as redback spiders. Pholcus phalangioides is known to be harmless to humans and a potential for the medicinal use of their silk has been reported. (Full article...)
The antlions are a group of about 2,000 species of insect in the neuropteranfamilyMyrmeleontidae. They are known for the predatory habits of their larvae, which mostly dig pits to trap passing ants or other prey. In North America, the larvae are sometimes referred to as doodlebugs because of the marks they leave in the sand. The adult insects are less well known due to their relatively short lifespans compared to the larvae. Adults, sometimes known as antlion lacewings, mostly fly at dusk or just after dark and may be mistakenly identified as dragonflies or damselflies.
Antlions have a worldwide distribution. The greatest diversity occurs in the tropics, but a few species are found in cold-temperate locations, one such being the European Euroleon nostras. They most commonly occur in dry and sandy habitats where the larvae can easily excavate their pits, but some larvae hide under debris or ambush their prey among leaf litter.
Antlions are poorly represented in the fossil record. Myrmeleontiformia is generally accepted to be a monophyletic group, and within the Myrmeleontoidea, the antlions' closest living relatives are thought to be the owlflies (Ascalaphidae). A 2019 study finds Myrmeleontidae to be monophyletic, aside from Stilbopteryginae and Palparinae, which form separate clades closer to Ascalaphidae. The predatory actions of the larvae have attracted attention throughout history and antlions have been mentioned in literature since classical times. (Full article...)
... that the discovery of the fossil giant ant Titanomyrma(pictured with rufous hummingbird) in Wyoming indicates that warmth-loving fauna spread through the north between Europe and America during hot spells in the Eocene?
Image 2Reconstruction of Mollisonia plenovenatrix, the oldest known arthropod with confirmed chelicerae (from Chelicerata)
Image 3The 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 6In 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 7Formation 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 14Body structure of a typical crustacean – krill (from Crustacean)
Image 15This 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 16Decapods, from Ernst Haeckel's 1904 work Kunstformen der Natur (from Crustacean)
Image 17Ghost 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 18Some 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 21Mature 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 22The fangs in spiders' chelicerae are so sclerotised as to be greatly hardened and darkened (from Arthropod exoskeleton)
Image 29 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)
The Painted Lady (Vanessa cardui) is a well-known colourful butterfly, found on every continent except Antarctica. It occurs in any temperate zone, including mountains in the tropics. The species is resident only in warmer areas, but migrates in spring, and sometimes again in autumn.
The Meadow Argus (Junonia villida) is a species of butterfly native to Australasia. Its brown wings are each covered with two distinctive black and blue eyespots as well as white and orange marks that appear on the edge of the wings. Males and females are similar in appearance and size, with females being slightly larger.
Leptosia nina, known as the psyche, is a species of butterfly in the family Pieridae (the sulphurs, yellows and whites), found in the Indian subcontinent, southeastern Asia, and Australia. It has a small wingspan of 2.5 to 5 cm (1 to 2 in). The upper side of the otherwise white forewing has a large, somewhat pear-shaped, black spot; this spot is also present on the underside which is scattered with greenish dots and speckles, sometimes arranged in bands. This L. nina butterfly was photographed in Kerala, India.
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.
Poli's stellate barnacle (Chthamalus stellatus) is a species of acorn barnacle common on rocky shores in South West England, Ireland, and Southern Europe. It is named after Italian scientist Giuseppe Saverio Poli. Depending upon environmental conditions and the amount of food available, it can reach up to 14 mm (0.55 in) in diameter.
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.
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.
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 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 citrus root weevil (Diaprepes abbreviatus) is a major agricultural pest weevil in several Caribbean countries and the U.S. state of Florida. The larvae feed on the roots of the host plant for several months. They often eat the taproot of the plant, which can kill it by depriving it of water and nutrients or by making it vulnerable to infection by fungi, or water moulds.
A nest of the tropical Asian giant honey bee, which consists of a single exposed honeycomb, an array of densely packed hexagonal cells made of beeswax. Honeycombs store food (honey and pollen) and house the "brood" (eggs, larvae, and pupae).
Two Melangyna viridiceps (called Common Hoverflies in Australia) mating in mid-air. The male, which can be identified by the eyes meeting at the top of its head, is on top. The term "hoverfly" refers to about 6,000 species of flying insects in the family Syrphidae. They are often seen hovering at flowers and are important pollinators.
Danaus genutia, the common tiger or striped tiger, is a species of brush-footed butterfly found in Sri Lanka, India, Myanmar, south-eastern Asia and Australia. It prefers areas of moderate to heavy rainfall, and typical habitats include scrubby jungle, deciduous forests and fallow land near habitations. The insect sequesters toxins from plants, and advertises its unpalatability by having prominent markings and striking colour patterns. This adult male common tiger, of the subspecies D. g. genutia, was photographed in Kerala, India.
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.
A macro shot of the head of a dragonfly, focusing on its compound eyes. Dragonfly eyes have up to 30,000 facets; each one is a separate light-sensing organ or ommatidium, arranged to give nearly a 360° field of vision.
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