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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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...)
Hughmilleriidae (the name deriving from the type genus Hughmilleria, which is named in honor of ScottishgeologistHugh Miller) is a family of eurypterids, an extinct group of aquatic arthropods. The hughmilleriids were the most basal members of the superfamily Pterygotioidea, in contrast with the more derived (more "advanced") families Pterygotidae and Slimonidae. Despite their classification as pterygotioids, the hughmilleriids possessed several characteristics shared with other eurypterid groups, such as the lanceolate telson (the most posterior segment of the body).
Hughmilleriids are defined as pterygotioid eurypterids with swimming legs similar to those of the type genus, Hughmilleria (that is, 7th and 8th leg segments narrow and 9th segment very small), and whose second to fifth pair of appendages were spiniferous. Some further diagnostic characters unite the group, such as the slightly enlarged chelicerae (frontal appendages) and the streamlined shape of their bodies. The family contains only two genera, Hughmilleria and Herefordopterus, though other genera have been referred to the family in the past, such as genera now considered part of families such as the Mycteroptidae and the Waeringopteridae.
The hughmilleriids were the most basal group of pterygotioid eurypterids, lacking the derived features that would come to evolve in the Slimonidae and Pterygotidae, such as flattened and expanded telsons (the posteriormost segment of the body, this feature is shared by both derived families) and enlarged cheliceral claws (exclusive to the pterygotids). In spite of the great similarity of both genera, Herefordopterus had derived characteristics that suggest a close relationship with Slimonidae and Pterygotidae, such as the marginal ornamentation of the telson. On the other hand, Hughmilleria had certain resemblance to the basal adelophthalmidEysyslopterus, sharing a triangular anterior carapace margin, possibly a plesiomorphic (of a common ancestor) trait. (Full article...)
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Throughout history, spiders have been depicted in popular culture, mythology and in symbolism. From Greek mythology to African folklore, the spider has been used to represent a variety of things, and endures into the present day with characters such as Shelob from The Lord of the Rings and Spider-Man from the eponymous comic series. It is also a symbol of mischief and malice for its toxic venom and the slow death it causes, which is often seen as a curse. In addition, the spider has inspired creations from an ancient geoglyph to a modern steampunkspectacle. Spiders have been the focus of fears, stories and mythologies of various cultures for centuries.
The spider has symbolized patience and persistence due to its hunting technique of setting webs and waiting for its prey to become ensnared. Numerous cultures attribute the spider's ability to spin webs with the origin of spinning, textile weaving, basket weaving, knotwork and net making. Spiders are associated with creation myths because they seem to weave their own artistic worlds. Philosophers often use the spider's web as a metaphor or analogy, and today terms such as the Internet or World Wide Web evoke the inter-connectivity of a spider web.
Puzzled by the geographical distribution of wildlife and fossils he collected on the voyage, Darwin began detailed investigations and, in 1838, devised his theory of natural selection. Although he discussed his ideas with several naturalists, he needed time for extensive research, and his geological work had priority. He was writing up his theory in 1858 when Alfred Russel Wallace sent him an essay that described the same idea, prompting immediate joint submission of both their theories to the Linnean Society of London. Darwin's work established evolutionary descent with modification as the dominant scientific explanation of diversification in nature. In 1871, he examined human evolution and sexual selection in The Descent of Man, and Selection in Relation to Sex, followed by The Expression of the Emotions in Man and Animals (1872). His research on plants was published in a series of books, and in his final book, The Formation of Vegetable Mould, through the Actions of Worms (1881), he examined earthworms and their effect on soil. (Full article...)
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The coconut crab (Birgus latro) is a terrestrial species of giant hermit crab, and is also known as the robber crab or palm thief. It is the largest terrestrial arthropod known, with a weight of up to 4.1 kg (9 lb). The distance from the tip of one leg to the tip of another can be as wide as 1 m (3 ft 3 in). It is found on islands across the Indian and Pacific Oceans, as far east as the Gambier Islands, Pitcairn Islands and Caroline Island and as far south as Zanzibar. While its range broadly shadows the distribution of the coconut palm, the coconut crab has been extirpated from most areas with a significant human population such as mainland Australia and Madagascar.
The coconut crab is the only species of the genusBirgus, and is related to the other terrestrial hermit crabs of the genus Coenobita. It shows a number of adaptations to life on land. Juvenile coconut crabs use empty gastropod shells for protection like other hermit crabs, but the adults develop a tough exoskeleton on their abdomens and stop carrying a shell. Coconut crabs have organs known as branchiostegal lungs, which they use for breathing instead of their vestigial gills. After the juvenile stage, they will drown if immersed in water for too long. They have an acute sense of smell which they use to find potential food sources, and which has developed convergently with that of insects.
Adult coconut crabs feed primarily on fleshy fruits, nuts, seeds, and the pith of fallen trees, but they will eat carrion and other organic matter opportunistically. Anything left unattended on the ground is a potential source of food, which they will investigate and may carry away – thereby getting the alternative name of "robber crab". The species is popularly associated with the coconut palm, yet coconuts are not a significant part of its diet. Although it lives in a burrow, the crab has been filmed climbing coconut and pandanus trees. No film shows a crab selectively picking coconut fruit, though they might dislodge ripe fruit that otherwise would fall naturally. When a crab is not near its burrow, climbing is an immediate escape route from predators. Sea birds eat young crabs, and both humans and larger, older crabs eat crabs of all ages. (Full article...)
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The paratype specimen ROMIP 65168; an anterior sclerite
Titanokorys is a genus of extinct hurdiid (peytoiid) radiodont (a grouping of primitive stemarthropods which lived during the early Paleozoic) that existed during the midCambrian. It is the largest member of its family from the Cambrian, with a body length of 50 cm (20 in) long, making it one of the largest animals of the time. It bears a resemblance to the related genus Cambroraster. Fossils of T. gainesi were first found within Marble Canyon in 2018. The fossils were not named until 2021 because they were assumed to be giant specimens of Cambroraster.
The creature was one of several genera of radiodonts known from the Burgess Shale, with some of the others being Cambroraster, Anomalocaris, Peytoia, and Hurdia. Titanokorys is distinguished from other Burgess Shale radiodonts because of its large anterior sclerite (head covering carapace) and a pair of spines on the anteroventral sides. Based on the shape of its appendages, Titanokorys is speculated to have used them to sift through the sand looking for prey. It is believed to have fed by using its anterior sclerite to scoop up organisms from the sea floor. Then it would use its frontal appendages (long grasping structures that all radiodonts possessed) to trap the prey item so it could start consuming it. Because of its size, Titanokorys was one of the dominant predators of the Burgess Shale and one of the largest animals in its ecosystem. (Full article...)
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Cimex lectularius
The Cimicidae are a family of small parasiticbugs that feed exclusively on the blood of warm-blooded animals. They are called cimicids or, loosely, bed bugs, though the latter term properly refers to the most well-known member of the family, Cimex lectularius, the common bed bug and its tropical relation Cimex hemipterus. The family contains over 100 species. Cimicids appeared in the fossil record in the Cretaceous period. When bats evolved in the Eocene, Cimicids switched hosts and now feed mainly on bats or birds. Members of the group have colonised humans on three occasions.
Cimicids usually feed on their host's blood every three to seven days, crawling away from the host and hiding while they digest the blood, which may take several days. This means that they specialise in vertebrate hosts that return regularly to particular sites to nest, roost or sleep. Birds and bats suit these specific requirements, as do humans now that they live in dwellings, and these are the main hosts used by the bugs. Most cimicids are able to go for long periods without feeding, over a year in some instances.
Cimicids are typically small, oval, flattened, wingless insects. They are stimulated to appear from their hiding places by cues such as a slight rise in the temperature of their surroundings. Among the family's distinctive characteristics are traumatic insemination, in which the male fertilises the eggs by piercing the female's abdominal wall with his intromittent organ. They also have distinctive paired structures called mycetomes inside their bodies, in which they harbour bacterial symbionts: these may help them to obtain nutrients they cannot get from blood. Although the insects may acquire viruses and other pathogens while feeding, these do not normally replicate inside the insect, and the infections are not transmitted to new hosts. (Full article...)
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Hemilepistus reaumuri is a species of woodlouse that lives in and around the deserts of North Africa and the Middle East, "the driest habitat conquered by any species of crustacean, not including insects which are now known to be crustaceans pancrustacea". It reaches a length of 22 mm (0.87 in) and a width of up to 12 mm (0.47 in), and has seven pairs of legs which hold its body unusually high off the ground. The species was described in the Description de l'Égypte after the French Campaign in Egypt and Syria of 1798–1801, but was first formally named by Henri Milne-Edwards in 1840 as Porcellio reaumuri. It reached its current scientific name in 1930 after the former subgenus Hemilepistus was raised to the rank of genus.
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...)
Termites are a group of detritophagouseusocialinsects which consume a wide 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 distantly related. About 2,972 extant species are currently described, 2,105 of which are members of the family Termitidae.
Termites comprise the infraorderIsoptera, or alternatively the epifamilyTermitoidae, 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...)
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Brownimecia clavata holotype
Brownimecia is an extinctgenus of ants, the only genus in the tribeBrownimeciini and subfamily Brownimeciinae of the Formicidae. Fossils of the identified species, Brownimecia clavata and Brownimecia inconspicua, are known from the Late Cretaceous of North America. The genus is one of several ants described from Late Cretaceous ambers of New Jersey. Brownimecia was initially placed in the subfamily Ponerinae, until it was transferred to its own subfamily in 2003; it can be distinguished from other ants due to its unusual sickle-like mandibles and other morphological features that makes this ant unique among the Formicidae. B. clavata is also small, measuring 3.43 millimetres (0.135 in), and a stinger is present in almost all of the specimens collected. The morphology of the mandibles suggest a high level of feeding specialization. (Full article...)
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Calliphora vomitoria, known as the blue bottle fly, orange-bearded blue bottle, or bottlebee, is a species of blow fly, a species in the family Calliphoridae. Calliphora vomitoria is the type species of the genusCalliphora. It is common throughout many continents including Europe, Americas, and Africa. They are fairly large flies, nearly twice the size of the housefly, with a metallic blue abdomen and long orange setae on the gena.
While adult flies feed on nectar, females deposit their eggs on rotting corpses, making them important forensic insects, as their eggs and timing of oviposition can be used to estimate time of death. (Full article...)
Ticks are parasitic arachnids of the order Ixodida. They are part of the mite superorder Parasitiformes. Adult ticks are approximately 3 to 5 mm in length depending on age, sex, species, and "fullness". Ticks are external parasites, living by feeding on the blood of mammals, birds, and sometimes reptiles and amphibians. The timing of the origin of ticks is uncertain, though the oldest known tick fossils are from the Cretaceous period, around 100 million years old. Ticks are widely distributed around the world, especially in warm, humid climates.
Ticks belong to two major families, the Ixodidae or hard ticks, and the Argasidae, or soft ticks. Nuttalliella, a genus of tick from southern Africa, is the only member of the family Nuttalliellidae, and represents the most primitive living lineage of ticks. Adults have ovoid/pear-shaped bodies (idiosomas) which become engorged with blood when they feed, and eight legs. Their cephalothorax and abdomen are completely fused. In addition to having a hard shield on their dorsal surfaces, known as the scutum, hard ticks have a beak-like structure at the front containing the mouthparts, whereas soft ticks have their mouthparts on the underside of their bodies. Ticks locate potential hosts by sensing odor, body heat, moisture, and/or vibrations in the environment.
Ticks have four stages to their life cycle, namely egg, larva, nymph, and adult. Ticks belonging to the Ixodidae family undergo either a one-host, two-host, or three-host life cycle. Argasid ticks have up to seven nymphal stages (instars), each one requiring blood ingestion, and as such, Argasid ticks undergo a multihost life cycle. Because of their hematophagous (blood-ingesting) diets, ticks act as vectors of many serious diseases that affect humans and other animals. (Full article...)
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Novomessor albisetosus worker specimen
Novomessor albisetosus, also known as the desert harvester ant, is a species of ant found in the United States and Mexico. A member of the genus Novomessor in the subfamily Myrmicinae, it was first described by Austrian entomologist Gustav Mayr in 1886. It was originally placed in the genus Aphaenogaster, but a recent phylogenetic study concluded that it is genetically distinct and should be separated. It is a medium-sized species, measuring 6 to 8.5 millimeters (0.2 to 0.3 in) and has a ferruginous body color. It can be distinguished from other Novomessor species by its shorter head and subparallel eyes.
Novomessor albisetosus is found in desert and woodland habitats, nesting underground or under stones. The ants are active during the morning and evening but not when it is midday or the middle of the night. They forage for foods such as insect pieces, plant tissues and fruit. They may forage individually but cooperate when transporting large food items. Army ants are known to prey on this species. Nuptial flights begin in June. Workers are considered matured when half of their time is spent outside. (Full article...)
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Restoration of the pretelson and telson of H. suecicus, showing the cercal blades, following Kjellesvig-Waering (1979)
Holmipterus is a problematic genus of eurypterid, an extinct group of aquatic arthropods. The type and only species of Holmipterus, H. suecicus, is known from deposits of Middle Silurian age in the Sweden. The generic name honours Gerhard Holm [sv], a renowned Swedish palaeontologist specialising in arthropods and crustaceans, and the species name suecicus is Latin for 'Swedish'.
Although Holmipterus was a large eurypterid and is known from multiple, albeit partial and fragmentary, specimens, it has proven difficult to determine where it fits in the eurypterid family tree. This is due to the fossil material referred to Holmipterus combining traits seen in different eurypterid groups, such as the Carcinosomatidae and Megalograptidae, and has some distinctive features, such as a telson (the posteriormost division of the body) with two articulating 'cercal blades', forming an organ capable of grasping. Though often classified either as a carcinosomatid or megalograptid, Holmipterus has also been classified as a genus of uncertain affinity within the Eurypterina suborder, or within the entire Eurypterida order. It is possible that the original 1979 description of Holmipterus suecicus reconstructed the telson inaccurately, and/or mistakenly combined fossil material actually belonging to two different genera. (Full article...)
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Myrmecia inquilina is a species of ant endemic to Australia in the subfamily Myrmeciinae, first discovered in 1955 and described by Athol Douglas and William Brown Jr. in 1959. These ants are large, measuring 21.4 millimetres (0.84 in). During the time of its discovery, Douglas and Brown announced M. inquilina as the first social parasite among the primitive subfamilies, and today it is one of the two known Myrmecia species to have no worker caste. Two host species are known, Myrmecia nigriceps and Myrmecia vindex. Aggression between M. inquilina and its host species does not occur, and colonies may only produce M. inquilina brood months after the inquiline queens begin to lay their eggs. Queens eat the colony brood or trophic eggs, and other Myrmecia species may kill M. inquilina queens if they reject them. Due to its restricted distribution and threats to its habitat, the ant is "vulnerable" according to the IUCN Red List. (Full article...)
... that the family placement for the fossil moth genus Dominickus was not noticed until entomologistNorman Tindale was looking at pictures of modern moths from Australia?
Image 2 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 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 5Some 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 10This 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 13Crab larva barely recognisable as a crab, radically changes its form when it undergoes ecdysis as it matures (from Arthropod exoskeleton)
Image 14 Honeybee larvae have flexible but delicate unsclerotised cuticles. (from Arthropod exoskeleton)
Image 15In 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 18Ghost 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 19Decapods, from Ernst Haeckel's 1904 work Kunstformen der Natur (from Crustacean)
Image 26Reconstruction of Mollisonia plenovenatrix, the oldest known arthropod with confirmed chelicerae (from Chelicerata)
Image 27Body structure of a typical crustacean – krill (from Crustacean)
Image 28Mature 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 33Formation 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)
Squilla mantis, a species of mantis shrimp, for sale at the fish auction of l'Ametlla de Mar in Catalonia, Spain. It is native to the Mediterranean Sea and adjacent warm parts of the Atlantic Ocean, where it burrows into muddy and sandy seabeds. It is the only native stomatopod to be fished for on a commercial scale in the Mediterranean.
The cryptic mantis (Sibylla pretiosa) is a mantid native to southern Africa. Its common name comes from its ability to grow asymmetrically to match the vegetation of its environment. They have unusual leaf-like projections on the joint of their four walking legs and leaf-like wings, generally the only green portion of the insect's otherwise brown and mottled exoskeleton. Adult females grow to 5–6 cm (2.0–2.4 in) in length while the males are generally about 1 cm smaller.
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 Forest scorpion (Cercophonius squama) is a scorpion native to southeastern Australia and Tasmania. The body is 25 to 40 millimetres (0.98 to 1.57 in) long, and coloured creamy yellow to orange brown with dark brown variegations. The legs are yellow with some dark brown pigment.
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 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."
A macro view of a Gonia capitatafly feeding on honey, showing its proboscis and pedipalps (the two appendages protruding from the proboscis), two types of insect mouthparts. The proboscis actually comprises the labium, a quadrupedal structure, and a sponge-like labellum at the end. Flies eat solid food by secreting saliva and dabbing it over the food item. As the saliva dissolves the food, the solution is then drawn up into the mouth as a liquid. The labellum's surface is covered by minute food channels which form a tube leading to the esophagus, and food is drawn up the channels by capillary action.
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.
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.
A honey bee extracts nectar from a flower using its proboscis. Tiny hairs covering the bee's body maintain a slight electrostatic charge, causing pollen from the flower's anthers to stick to the bee's hairs, allowing for pollination when the bee moves on to another flower.
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.
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.
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.
The red rock crab (Grapsus grapsus) is one of the most common crabs along the western coast of the Americas. Adults are quite variable in color, including brownish-red, mottled or spotted brown, pink, yellow, bright orange and red. It feeds on algae primarily, sometimes sampling other plant matter and dead animals.
Attacus taprobanis is a species of moth in the family Saturniidae native to southern India and Sri Lanka. This adult male, photographed in Kadavoor, Kerala, developed from a larva feeding on a mahogany tree. When ready to pupate, the larva formed a papery cocoon 7.5 cm (3 in) long interwoven with a leaf; before doing this, the larva had attached the leaf to the stem with a silken thread and cut the leaf stalk. The colours of the dying leaf provided camouflage for the pupa, and the adult insect emerged some 24 days later.
Argiope trifasciata, the banded garden or banded orb-weaving spider, is a species of arachnid in the family Araneidae. It is native to North and South America but has spread to other parts of the world. This ventral view of a female A. trifasciata shows her in the centre of her web, which can reach a diameter of 60 cm (24 in). The function of the zig-zag web decorations is unclear, but they may serve to make the spider appear larger or to act as a warning sign.
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.
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.
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