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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The head of a small white butterfly (Pieris rapae). Note the upward pointing labial palpi on both sides of the coiled proboscis.
The external morphology of Lepidoptera is the physiological structure of the bodies of insects belonging to the order Lepidoptera, also known as butterflies and moths. Lepidoptera are distinguished from other orders by the presence of scales on the external parts of the body and appendages, especially the wings. Butterflies and moths vary in size from microlepidoptera only a few millimetres long, to a wingspan of many inches such as the Atlas moth. Comprising over 160,000 described species, the Lepidoptera possess variations of the basic body structure which has evolved to gain advantages in adaptation and distribution.
Lepidopterans undergo complete metamorphosis, going through a four-stage life cycle: egg, larva or caterpillar, pupa or chrysalis, and imago (plural: imagines) / adult. The larvae – caterpillars – have a toughened (sclerotised) head capsule, chewing mouthparts, and a soft body, that may have hair-like or other projections, three pairs of true legs, and up to five pairs of prolegs. Most caterpillars are herbivores, but a few are carnivores (some eat ants, aphids, or other caterpillars) or detritivores. Larvae are the feeding and growing stages and periodically undergo hormone-induced ecdysis, developing further with each instar, until they undergo the final larval–pupal moult. The larvae of many lepidopteran species will either make a spun casing of silk called a cocoon and pupate inside it, or will pupate in a cell under the ground. In many butterflies, the pupa is suspended from a cremaster and is called a chrysalis.
The adult body has a hardened exoskeleton, except for the abdomen which is less sclerotised. The head is shaped like a capsule with appendages arising from it. Adult mouthparts include a prominent proboscis formed from maxillary galeae, and are adapted for sucking nectar. Some species do not feed as adults, and may have reduced mouthparts, while others have them modified for piercing and suck blood or fruit juices. Mandibles are absent in all except the Micropterigidae which have chewing mouthparts. Adult Lepidoptera have two immobile, multi-faceted compound eyes, and only two simple eyes or ocelli, which may be reduced. The three segments of the thorax are fused together. Antennae are prominent and besides the faculty of smell, also aid navigation, orientation, and balance during flight. In moths, males frequently have more feathery antennae than females, for detecting the female pheromones at a distance. There are two pairs of membranouswings which arise from the mesothoracic (middle) and metathoracic (third) segments; they are usually completely covered by minute scales. The two wings on each side act as one by virtue of wing-locking mechanisms. In some groups, the females are flightless and have reduced wings. The abdomen has ten segments connected with movable inter-segmental membranes. The last segments of the abdomen form the external genitalia. The genitalia are complex and provide the basis for family identification and species discrimination. (Full article...)
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T. tatusia worker from El Campano, Magdalena, Colombia
Tatuidris, or armadillo ant, is a rare genus of ants consisting of a single species, Tatuidris tatusia. The ants are small in size and inhabit the leaf litter of Neotropical forests in Central and South America, from Mexico to Brazil. Workers are ferruginous-colored to dark red and present a distinctive morphology, consisting of a shield-like head with a broad vertex, ventrally-turned heavy mandibles which do not overlap at full closure, and unique among ants – an antenna socket apparatus sitting upside-down. Little is known about the biology of the ants, but they are likely nocturnal and specialist predators.
Tatuidris was first described in 1968 and initially placed in the myrmicinetribe Agroecomyrmecini, together with two fossil genera. Since the original description, the systematic status of the tribe has been the focus of debate. (Full article...)
Worker policing is a behavior seen in colonies of social hymenopterans (ants, bees, and wasps) whereby worker females eat or remove eggs that have been laid by other workers rather than those laid by a queen. Worker policing ensures that the offspring of the queen will predominate in the group. In certain species of bees, ants and wasps, workers or the queen may also act aggressively towards fertile workers. Worker policing has been suggested as a form of coercion to promote the evolution of altruistic behavior in eusocial insect societies.[dubious – discuss] Proposed mechanisms for the recognition of worker-laid eggs or active reproductive workers include marker hydrocarbons on the surface of queen-laid eggs, cuticle hydrocarbons on reproductive workers, and recognition of nest-mates. In rare cases, worker-laid eggs carry mimicked queen hydrocarbons and escape policing, a condition known as the anarchic syndrome.
Not all forms of policing require the presence of a queen; it also occurs in a few species of ants which establish a dominance hierarchy of reproductive female workers, where top-ranking individuals reproduce. (Full article...)
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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 speciesMyrmica schencki as a larva by using chemical mimicry to trick the ants into believing that they are ant larvae; thus, the ants bring P. rebelicaterpillars 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...)
Iridomyrmex is a genus of ants called rainbow ants (referring to their blue-green iridescent sheen) first described by Austrian entomologist Gustav Mayr in 1862. He placed the genus in the subfamilyDolichoderinae of the family Formicidae. It has 79 described species and five fossil species. Most of these ants are native to Australia; others are found in Asia and Oceania, and they have been introduced to Brazil, New Zealand, and the United Arab Emirates. Fossil species are known from China, France, and the United States.
These ants are known to be an ecologically dominant and important group of ants, but they are sometimes regarded as pests because they disturb soil and enter human houses. Farmers in rural Australia place animal carcasses on meat ant (I. purpureus) mounds as a method of disposing of them; meat ants consume the carcass and reduce it to bones in a matter of weeks. Meat ants also engage in ritualised fighting, which helps prevent casualties and solve territorial disputes between neighbouring colonies. The largest members of this genus are those of the I. purpureus species group, measuring 8 mm (0.31 in).
After their nuptial flight, queen ants may establish a colony by themselves, by budding, or cooperatively, where a subset of the colony migrates to a new location or when multiple queens help find a suitable nesting spot, but they display intolerance to each other when workers are present. The eggs take 44 to 61 days to fully develop into adults. Ants of the genus live in a wide variety of habitats and nest in soil in numbers that range from a few hundred individuals to over 300,000 in a single colony. Depending on the species, nests are large mounds covered in pebbles with multiple entrances, while others live above ground in twig nests. In some cases, ants dwell in several nest sites connected by paths; some of these nests can extend to 650 m (2,130 ft) in length. Some species associate with caterpillars and butterflies that provide the ants with secretions and honeydew, and I. bicknelli pollinates orchids. These ants are predators and scavengers; they hunt for prey to feed their young. Notably, these ants are immune to the toxins of the cane toad and feed on the juveniles. Predators such as spiders, birds, lizards, and other ants prey on Iridomyrmex ants. (Full article...)
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Alice E. Gray (June 7, 1914 – April 27, 1994) was an American entomologist and origamist. She worked as an entomologist at the American Museum of Natural History (AMNH) in New York for 43 years, writing, illustrating, and creating large models of insects. Known as the "Bug Lady", she conducted outreach and education in the museum, in local schools, and appeared on The Tonight Show. She began practicing origami first as an extension of her interest in insects, starting a tradition of using origami creatures to decorate the museum's Christmas tree. In the 1960s, she became more involved with the origami community and, in 1978, co-founded the Friends of the Origami Center of America in New York with Lillian Oppenheimer and Michael Shall, now known as OrigamiUSA. (Full article...)
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Interpretive drawing of PIN 1271/2, the holotype of Dvulikiaspis menneri
Its prosoma (head) was subquadrate (almost square) to parabolic (nearly U-shaped), with (bean-shaped) to subovate (nearly oval) eyes and surrounded by a marginal rim. The abdomen was composed by a fused buckler and a postabdomen that occupied most of the body length, while the telson (the posteriormost division of the body) was small and semicircular in shape. The appendages (limbs) were uniform. The sixth and last pair of them had a paddle-like shape and was placed in front of the midpoint of the prosoma. The largest specimen was 2.64 centimetres (1.04 inches) long.
The first fossil was described in 1959 as a new species of the eurypteridStylonurus, while the other two were discovered in 1974. It would not be until 2014 when D. menneri was recognized as a chasmataspidid genus, being placed in the familyDiploaspididae. However, Dvulikiaspis was similar to Loganamaraspis and especially Hoplitaspis, with which it could form a new separate family of chasmataspidids. (Full article...)
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Winged and wingless forms
Thrips (orderThysanoptera) are minute (mostly 1 mm (0.039 in) long or less), slender insects with fringed wings and unique asymmetrical mouthparts. Entomologists have described approximately 7,700 species. They fly only weakly and their feathery wings are unsuitable for conventional flight; instead, thrips exploit an unusual mechanism, clap and fling, to create lift using an unsteady circulation pattern with transient vortices near the wings.
Thrips are a functionally diverse group, with nearly half of the known species being fungivorous. A small proportion of species of thrips are serious pests of commercially important crops. Some of these serve as vectors for over 20 viruses that cause plant disease, especially the Tospoviruses. Many flower-dwelling species bring benefits as pollinators, with some predatory thrips feeding on small insects or mites. In the right conditions, such as in greenhouses, invasive species can exponentially increase in population size and form large swarms because of a lack of natural predators coupled with their ability to reproduce asexually, making them destructive to crops. Due to their cryptic nature, thrips may aggregate in household objects such as furniture, bedding and computer monitors – in the latter case by forcing their way in between the LCD and its glass covering. Their identification to species by standard morphological characteristics is often challenging. (Full article...)
Flea, the common name for the orderSiphonaptera, includes 2,500 species of small flightless insects that live as external parasites of mammals and birds. Fleas live by ingesting the blood of their hosts. Adult fleas grow to about 3 millimetres (1⁄8 inch) long, are usually brown, and have bodies that are "flattened" sideways or narrow, enabling them to move through their hosts' fur or feathers. They lack wings; their hind legs are extremely well adapted for jumping. Their claws keep them from being dislodged, and their mouthparts are adapted for piercing skin and sucking blood. They can leap 50 times their body length, a feat second only to jumps made by another group of insects, the superfamily of froghoppers. Flea larvae are worm-like, with no limbs; they have chewing mouthparts and feed on organic debris left on their hosts' skin.
Genetic evidence indicates that fleas are a specialised lineage of parasitic scorpionflies (Mecoptera) sensu lato, most closely related to the family Nannochoristidae. The earliest known fleas lived in the Middle Jurassic; modern-looking forms appeared in the Cenozoic. Fleas probably originated on mammals first and expanded their reach to birds. Each species of flea specializes, more or less, on one species of host: many species of flea never breed on any other host; some are less selective. Some families of fleas are exclusive to a single host group; for example, the Malacopsyllidae are found only on armadillos, the Ischnopsyllidae only on bats, and the Chimaeropsyllidae only on elephant shrews.
Cyrtophora citricola, also known as the tropical tent-web spider, is an orb-weaver spider in the family Araneidae. It is found in Asia, Africa, Australia, Costa Rica, Hispaniola, Colombia, and Southern Europe and in 2000, it was discovered in Florida. C. citricola differs from many of its close relatives due its ability to live in a wide variety of environments. In North America and South America, the spider has caused extensive damage to agricultural operations.
C. citricola is in the orb web spider family, but its orb webs are considered atypical. They have a thick silk strand barrier above the orb and a thinner barrier below the orb. This gives the webs a horizontal mesh-like appearance. The spider has developed distinct and specific prey-capturing techniques using its unconventional webs. The prey flies into the upper mesh layer of the web and is deflected into the orb web. The spider then collects and stores the prey in its web. The difference in C. citricola's web silk stems from physiological variations in its spinning apparatuses, as compared to other closely related species. Its webs are non-adhesive and do not require daily respinning.
This spider is one of the few species to exhibit a variable level of sociality. C. citricola can be seen in colonies, which may have arisen due to reduced predation. Within these colonies, each spider has its own web that is linked to other spiders through communal webbing. The spider webs are often built in large matrices next to one another and can span entire trees. The spider usually peacefully coexists with other spiders in the colony. However, at times the spider may have to ward off other spiders in the colony that may try and claim its web. (Full article...)
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Illustration of the specimen BGS GSM Zf-2864 of S. abbreviatus, which preserves the telson and the tenth to twelfth abdominal segments.
Salteropterus is a genus of eurypterid, an extinct group of aquatic arthropods. Fossils of Salteropterus have been discovered in deposits of Late Silurian age in Britain. Classified as part of the family Slimonidae, the genus contains one known valid species, S. abbreviatus, which is known from fossils discovered in Herefordshire, England, and a dubious species, S. longilabium, with fossils discovered in Leintwardine, also in Herefordshire. The generic name honours John William Salter, who originally described S. abbreviatus as a species of Eurypterus in 1859.
Salteropterus is assumed to have been quite similar to its close relative Slimonia, but the fragmentary nature of the fossil remains of Salteropterus make direct comparisons difficult. Salteropterus does however preserve a highly distinctive telson (the posteriormost division of the body) unlike any other in the Eurypterida. Beginning with an expanded and flattened section, like that of Slimonia, the telson ends in a long stem that culminates in a tri-lobed structure at its end. Though the exact function remains unknown, this structure might have been used for additional balancing alongside the flattened part preceding it. (Full article...)
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Insects, such as this scorpionfly, have a three-part body: head with large compound eyes and antennae, a thorax with three pairs of legs and often wings, and a segmented abdomen.
The insect nervous system consists of a brain and a ventral nerve cord. Most insects reproduce by laying eggs. Insects breathe air through a system of paired openings along their sides, connected to small tubes that take air directly to the tissues. The blood therefore does not carry oxygen; it is only partly contained in vessels, and some circulates in an open hemocoel. Insect vision is mainly through their compound eyes, with additional small ocelli. Many insects can hear, using tympanal organs, which may be on the legs or other parts of the body. Their sense of smell is via receptors, usually on the antennae and the mouthparts.
Nearly all insects hatch from eggs. Insect growth is constrained by the inelastic exoskeleton, so development involves a series of molts. The immature stages often differ from the adults in structure, habit and habitat. Groups that undergo four-stage metamorphosis often have a nearly immobile pupa. Insects that undergo three-stage metamorphosis lack a pupa, developing through a series of increasingly adult-like nymphal stages. The higher level relationship of the insects is unclear. Fossilized insects of enormous size have been found from the Paleozoic Era, including giant dragonfly-like insects with wingspans of 55 to 70 cm (22 to 28 in). The most diverse insect groups appear to have coevolved with flowering plants. (Full article...)
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Lycorma imperialis is a planthopperindigenous to parts of China and Indo-Malaysia. L. imperialis was originally discovered in 1846 by Adam White and has one recognized non-nominate subspecies, L. i. punicea. L. imperialis has undergone a number of reclassifications since its discovery and is one of four species in the genusLycorma. L. imperialis follows a hemimetabolous life cycle and will undergo a series of nymphal stages (instars) before maturing to an adult.
Lycorma imperialis and L. i. punicea are referred to as "lanternflies" or "lantern bugs" due to their crimson hindwings and their forewings, which can range from blue green to brick red. They do not, however, emit light. L. imperialis can cause substantial damage to agricultural industries due to its specialized, sap sucking mouthparts and the resulting mold that develops from its honeydew excrement. (Full article...)
Mecoptera (from the Greek: mecos = "long", ptera = "wings") is an order of insects in the superorder Holometabola with about six hundred species in nine families worldwide. Mecopterans are sometimes called scorpionflies after their largest family, Panorpidae, in which the males have enlarged genitals raised over the body that look similar to the stingers of scorpions, and long beaklike rostra. The Bittacidae, or hangingflies, are another prominent family and are known for their elaborate mating rituals, in which females choose mates based on the quality of gift prey offered to them by the males. A smaller group is the snow scorpionflies, family Boreidae, adults of which are sometimes seen walking on snowfields. In contrast, the majority of species in the order inhabit moist environments in tropical locations.
The Mecoptera are closely related to the Siphonaptera (fleas), and a little more distantly to the Diptera (true flies). They are somewhat fly-like in appearance, being small to medium-sized insects with long slender bodies and narrow membranous wings. Most breed in moist environments such as leaf litter or moss, and the eggs may not hatch until the wet season arrives. The larvae are caterpillar-like and mostly feed on vegetable matter, and the non-feeding pupae may pass through a diapause until weather conditions are favorable.
Early Mecoptera may have played an important role in pollinating extinct species of gymnosperms before the evolution of other insect pollinators such as bees. Adults of modern species are overwhelmingly predators or consumers of dead organisms. In a few areas, some species are the first insects to arrive at a cadaver, making them useful in forensic entomology. (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 in the burrowing wolf spiderAllocosa brasiliensis, males often eat older, less fecund females that they lured into their burrow using pheromones, while preferring to mate with virgins?
The following are images from various arthropod-related articles on Wikipedia.
Image 1The 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 2 Honeybee larvae have flexible but delicate unsclerotised cuticles. (from Arthropod exoskeleton)
Image 8Mature 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 9Decapods, from Ernst Haeckel's 1904 work Kunstformen der Natur (from Crustacean)
Image 10Reconstruction of Mollisonia plenovenatrix, the oldest known arthropod with confirmed chelicerae (from Chelicerata)
Image 11Some 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 13Ghost 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 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 20 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 29In 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)
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.
A honeycomb is a mass of hexagonal prismaticwax cells built by honey bees in their hives to contain their larvae and stores of honey and pollen. Honey bees consume about 8.4 lb (3.8 kg) of honey to secrete 1 lb (0.5 kg) of wax. As such, many beekeepers attempt to conserve honeycombs where possible.
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.
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).
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.
The yellow fever mosquito (Aedes aegypti) is a species of mosquito known for its ability to spread yellow fever and dengue fever. The mosquito can be recognized by the white markings on its legs and a marking in the form of a lyre on its thorax. Though originally from Africa, the yellow fever mosquito can now be found in tropical regions around the world.
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 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.
The head and mandibles of an Australianbull ant. Insect mandibles grasp, crush, or cut the insect’s food, or defend against predators or rivals. These mandibles move in the horizontal plane unlike those of the vertebrates.
Sympetrum danae, the black darter or black meadowhawk, is a species of dragonfly found in northern Europe, Asia, and North America. Both sexes are black and yellow, but the abdomen of the male is largely black while that of the female is largely yellow. Breeding takes place in shallow acidic pools, lake margins and ditches in lowland heaths and moorland bogs. The female lays her eggs during flight by dipping the tip of her abdomen into the water. The eggs hatch the following spring, the larvae developing very rapidly and emerging as adults in as little as two months. The male seen here is perched on a frond of bracken on Warren Heath in Hampshire, England.
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 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.
Pieris brassicae, the large white, is a species of butterfly in the family Pieridae, common in Europe, Asia and North Africa. The larva pictured here, which was found at a market in Fronton, France, is a serious pest of plants in the cabbage family, Brassicaceae. The eggs are laid in batches on the undersides of the leaves of plants rich in mustard-oil glucosides, and consumption of these substances as they chew the leaves makes the larvae distasteful; the bright colouration of the larvae signals to predators that they taste bad. Additionally, the adult butterflies emit an unpleasant smell and display warning colours.
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 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 compound eye is a visual organ found in certain arthropods. The compound eye consists of between 12 and 1,000 ommatidia, little dark/bright sensors. The image perceived by the arthropod is "recalculated" from the numerous ommatidia which point in slightly different directions. In contrast to other eye types, there is no central lens or retina. Though the resulting image is poor in resolution, it can detect quick movements and, in some cases, the polarization of light.
Dragonflies have about 30,000 facets to their compound eyes, giving them nearly a 360° field of vision.
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