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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Image 1
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...)
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...)
Image 3
Andreacarus voalavo is a
parasiticmite found on the
Malagasy rodent Voalavo gymnocaudus. First described in 2007, it is closely related to Andreacarus gymnuromys and Andreacarus eliurus, which are found on other Malagasy rodents. The length of the idiosoma, the main body, is 630 to 670
μm in females and 450 to 480 μm in males. Unlike A. eliurus, this species lacks distinct
sternal glands (secretory organs) between two
lyrifissures (sensory organs) on the lower part of the female body. The pilus dentilis, a sensory organ on the
chelicera, is serrate, which distinguishes it from A. gymnuromys. Females of A. gymnuromys also have a less ornamented
sternal shield (covering part of the underparts) and shorter
setae (bristles) on the upperparts. (Full article...)
It is a poorly-known genus whose
carapace (
dorsal plate of the
prosoma, head) was semiovate bordered by a marginal rim, with
eyeslaterally placed, a preabdomen and postabdomen (the two halves of the
abdomen) with six
segments each and a short spike-like
telson (which was the posteriormost division of the body). It reached a total length of 7.5 centimetres (2.9 inches). These characteristics place Tylopterella in the
familyOnychopterellidae together with Onychopterella and Alkenopterus.
Tylopterella is notable for its thick
ornamentation and general body surface. Its paired
tubercles or knobs in the top of its second to fifth segments differentiates it from many other eurypterids. This thickness that its body possessed is due to the highly saline conditions to which Tylopterella had to adapt in the
Guelph Formation; other
organisms with reinforced shells have also been found in the same place. (Full article...)
Prionomyrmecini is an
anttribe belonging to the subfamily
Myrmeciinae established by
William Morton Wheeler in 1915. Two members are a part of this tribe, the extant Nothomyrmecia and the extinct Prionomyrmex. The tribe was once considered a subfamily due to the similarities between Nothomyrmecia and Prionomyrmex, but such reclassification was not widely accepted by the scientific community. These ants can be identified by their long slender bodies, powerful stingers and elongated mandibles. Fossil Prionomyrmecini ants were once found throughout Europe, possibly nesting in trees and preferring jungle habitats. Today, Prionomyrmecini is only found in Australia, preferring old-growth mallee woodland surrounded by Eucalyptus trees. Nothomyrmecia workers feed on nectar and arthropods, using their compound eyes for prey and navigational purposes. Owing to their primitive nature, they do not recruit others to food sources or create pheromone trails. Nothomyrmecia colonies are small, consisting of 50 to 100 individuals. (Full article...)
Image 6
Souvenir theatre card
Henry Edwards (27 August 1827 – 9 June 1891) was an English stage actor, writer and
entomologist who gained fame in Australia, San Francisco and New York City for his theatre work.
Edwards was drawn to the theatre early in life, and he appeared in amateur productions in London. After sailing to Australia, Edwards appeared professionally in
Shakespearean plays and light comedies primarily in Melbourne and Sydney. Throughout his childhood in England and his acting career in Australia, he was greatly interested in
collecting insects, and the
National Museum of Victoria used the results of his Australian fieldwork as part of the genesis of their collection.
In San Francisco, Edwards was a founding member of the
Bohemian Club, and a gathering in Edwards' honour was the spark which began the club's traditional summer encampment at the
Bohemian Grove. As well, Edwards cemented his reputation as a preeminent stage actor and theatre manager. After writing a series of influential studies on
Pacific Coast butterflies and moths he was elected life member of the
California Academy of Sciences. Relocating to the
East Coast, Edwards spent a brief time in Boston theatre. This led to a connection to
Wallack's Theatre and further renown in New York City. There, Edwards edited three volumes of the journal Papilio and published a major work about the life of the butterfly. His large collection of insect specimens served as the foundation of the
American Museum of Natural History's butterfly and moth studies. (Full article...)
Image 7
Dyspanopeus sayi is a
species of mud
crab that is native to the
Atlantic coast of North America. It has also become established outside its native range, living in
Swansea Docks since 1960, the
Mediterranean Sea since the 1970s, the
North Sea since 2007 and the
Black Sea since 2010. It can reach a
carapace width of 20 mm (0.8 in), and has black tips to its unequal claws. It feeds on
bivalves and
barnacles, and is in turn eaten by
predators including the Atlantic blue crab, Callinectes sapidus. Eggs are produced from spring to autumn, the offspring reach sexual maturity the following summer, and individuals can live for up to two years. The closest relative of D. sayi is D. texanus, which lives in the
Gulf of Mexico; the two species differ in subtle features of the genitalia and the last pair of
walking legs. (Full article...)
Image 8
Varroa destructor, the Varroa mite, is an
external parasiticmite that attacks and feeds on
honey bees and is one of the most damaging honey bee pests in the world. A significant mite infestation leads to the death of a honey bee colony, usually in the late autumn through early spring. Without management for Varroa mite, honey bee colonies typically collapse within 2 to 3 years in temperate climates. These mites can infest Apis mellifera, the western honey bee, and Apis cerana, the Asian honey bee. Due to very similar physical characteristics, this species was thought to be the closely related Varroa jacobsoni prior to 2000, but they were found to be two separate species after DNA analysis.
Parasitism of bees by mites in the genus Varroa is called
varroosis. The Varroa mite can reproduce only in a honey bee colony. It attaches to the body of the bee and weakens the bee. The species is a vector for at least five debilitating bee viruses, including
RNA viruses such as the
deformed wing virus (DWV). The Varroa mite is the parasite with possibly the most pronounced economic impact on the
beekeeping industry and is one of multiple stress factors contributing to the higher levels of bee losses around the world. Varroa mite has also been implicated as one of the multiple causes of
colony collapse disorder.
Management of this pest focuses on reducing mite numbers through monitoring to avoid significant hive losses or death. 3% of bees infested in a hive is considered an
economic threshold where damage is high enough to warrant additional management. Pesticides are available, though some are difficult to time correctly while avoiding harm to the hive, and resistance has occurred for others. Screened bottom boards on hives can be used for both monitoring and mite removal, and drone comb that mites prefer can be used as a trap to remove mites from the hive. Honey bee lines in breeding programs also show partial resistance to Varroa mite through increased hygienic behavior that is being incorporated as an additional management strategy. (Full article...)
Image 9
The type material of E. clevelandi: a body segment (top; with zoomed-in detail of the integument) and an endognathary appendage (bottom)
Echinognathus is a genus of
eurypterid, an extinct group of aquatic
arthropods. The type and only species of Echinognathus, E. clevelandi, is known from deposits of Late
Ordovician age in the
United States. The generic name is derived from the
Neo-Latinechino- ("spiny") and the
Greekgnáthos ("jaw"), in reference to a spiny endognathary (used to handle food) appendage part of the fossil type material.
Echinognathus is only known from fragmentary fossil material, consisting of body segments, an appendage used to handle food and possibly other body segments. The genus is distinguished from other eurypterids by the large number of elongated and curved spines, blade-like in life, on its limbs. Initially assumed to represent a species of Eurypterus, these distinguishing features were quickly noticed and deemed important enough to designate Echinognathus as its own genus. With some additional fossil assigned to Echinognathus in the early 20th century, the genus was noted to be similar to Megalograptus, another eurypterid with spiny limbs. In 1955, Echinognathus and Megalograptus were placed into their own taxonomic family of eurypterids, the
Megalograptidae.
Based on the proportions of other eurypterids, Echinognathus would have been a medium-sized predator, reaching approximately 45 centimeters (17.7 in) in length. The spines on its limbs were presumably used for active prey capture, securing food and carrying it to the mouth. The fossils of Echinognathus are known from what was once marine environments, and it lived alongside a fauna including
graptolites,
brachiopods,
cephalopods and
trilobites. (Full article...)
Image 10
Myrmecia nigriceps worker from Strangways, Victoria
Myrmecia nigriceps, also known as the black-headed bull ant, is a species of ant endemic to
Australia. A member of the genus Myrmecia in the subfamily
Myrmeciinae, it was first
described by Austrian entomologist
Gustav Mayr in 1862. These ants are large, varying from 19 to 23 millimetres (0.75 to 0.91 in) in length. However, colonies contain workers that are much smaller, usually half the size of normal workers. The queens are the largest while the males are the smallest, which can be easily identified due to their small mandibles.
Mainly nocturnal M. nigriceps is found in hot hilly areas and woodland, nesting underground in mounds. The ant's diet consists of sweet liquids from flowering plants and invertebrate prey, which are fed to the carnivorous larvae. Spiders are known to eat these ants, and echidnas consume the larvae and pupae. Like other Myrmecia species, M. nigriceps ants possess a powerful and painful sting, and the venom is capable of inducing allergic reactions in sensitive people. (Full article...)
Image 11
P. longiceps
Prionomyrmex is an extinct
genus of
bulldog ants in the
subfamilyMyrmeciinae of the family
Formicidae. It was first described by
Gustav Mayr in 1868, after he collected a
holotype worker of P. longiceps in
Baltic amber. Three species are currently described, characterised by their long mandibles, slender bodies and large size. These ants are known from the
Eocene and
Late Oligocene, with fossil specimens only found around
Europe. It is suggested that these ants preferred to live in jungles, with one species assumed to be an
arboreal nesting species. These ants had a powerful stinger that was used to subdue prey. In 2000, it was suggested by Cesare Baroni Urbani that the living species Nothomyrmecia macrops and a species he described both belonged to Prionomyrmex, but this proposal has not been widely accepted by the entomological community. Instead, scientists still classify the two genera distinctive from each other, making Nothomyrmecia a valid genus. (Full article...)
Paleomerus is one of the oldest arthropods, being sometimes interpreted as the model of the first
arachnomorphs. It is part of the order Strabopida, a poorly known group closely related to the
aglaspidids of uncertain affinities, often being ignored by researchers and authors due to the poor preservation and abundance of their
fossils. It has been suggested that Paleomerus and the closely related Strabops could be
synonymous with each other, since they differ only in the size of the
telson (the posteriormost division of the body) and the position of the
eyes. These two genera were originally deferred by a hypothetical twelfth
segment in Paleomerus, but after the discovery and description of a fourth specimen of P. hamiltoni, it has been shown that this segment actually represents the tail of the animal. (Full article...)
Image 13
Plexippoides regius in South Korea
Plexippoides regius (
Korean: 왕어리두줄깡충거미;
RR: Wangeoridujulkkangchunggeomi) is a
species of
jumping spider in the
genusPlexippoides. The species was first
described by
Wanda Wesołowska in 1981 based on specimens from North Korea but its
distribution has been extended to include China, Russia and South Korea, with examples found as far as
Sichuan. The spider is small, with a body length between 6.9 and 8.65 mm (0.27 and 0.34 in), the female being generally larger than the male. It is distinguished by the two brown lines that stretch across the back of its
carapace and
abdomen that is recalled in its Korean name. Otherwise, the spider varies in coloration, with some examples having an orange or yellow-brown carapace and others dark brown. The male has a long
embolus that encircles the
palpal bulb. The female has complex seminal ducts that lead to heavily
sclerotised and many-chambered
spermathecae. (Full article...)
A wasp is any
insect of the narrow-waisted suborder
Apocrita of the order
Hymenoptera which is neither a
bee nor an
ant; this excludes the broad-waisted
sawflies (Symphyta), which look somewhat like wasps, but are in a separate suborder. The wasps do not constitute a
clade, a complete natural group with a single ancestor, as bees and ants are deeply nested within the wasps, having evolved from wasp ancestors. Wasps that are members of the clade
Aculeata can
sting their prey.
The most commonly known wasps, such as
yellowjackets and
hornets, are in the family
Vespidae and are
eusocial, living together in a nest with an egg-laying queen and non-reproducing workers. Eusociality is favoured by the unusual
haplodiploid system of
sex determination in Hymenoptera, as it makes sisters exceptionally closely related to each other. However, the majority of wasp species are solitary, with each adult female living and breeding independently. Females typically have an
ovipositor for laying eggs in or near a food source for the larvae, though in the
Aculeata the ovipositor is often modified instead into a
sting used for defense or prey capture. Wasps play many
ecological roles. Some are
predators or pollinators, whether to feed themselves or to provision their nests. Many, notably the
cuckoo wasps, are
kleptoparasites, laying eggs in the nests of other wasps. Many of the solitary wasps are
parasitoidal, meaning they lay eggs on or in other insects (any life stage from egg to adult) and often
provision their own nests with such
hosts. Unlike true parasites, the wasp larvae eventually kill their hosts. Solitary wasps parasitize almost every
pest insect, making wasps valuable in
horticulture for
biological pest control of species such as
whitefly in
tomatoes and other crops.
Wasps first appeared in the fossil record in the
Jurassic, and diversified into many surviving superfamilies by the
Cretaceous. They are a successful and diverse group of insects with tens of thousands of described species; wasps have spread to all parts of the world except for the polar regions. The largest social wasp is the
Asian giant hornet, at up to 5 centimetres (2.0 in) in length; among the largest solitary wasps is a group of species known as
tarantula hawks, along with the giant scoliid of Indonesia (Megascolia procer). The smallest wasps are solitary
parasitoid wasps in the family
Mymaridae, including the world's smallest known insect, with a body length of only 0.139 mm (0.0055 in), and the smallest known flying insect, only 0.15 mm (0.0059 in) long. (Full article...)
Image 2In
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 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 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 12Decapods, from Ernst Haeckel's 1904 work Kunstformen der Natur (from Crustacean)
Image 13Formation 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 16The fangs in spiders' chelicerae are so sclerotised as to be greatly hardened and darkened (from Arthropod exoskeleton)
Image 17Body structure of a typical crustacean – krill (from Crustacean)
Image 18 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 22Some 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 23Crab larva barely recognisable as a crab, radically changes its form when it undergoes ecdysis as it matures (from Arthropod exoskeleton)
Image 27Ghost 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 29Reconstruction of Mollisonia plenovenatrix, the oldest known arthropod with confirmed chelicerae (from Chelicerata)
Image 30The
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)
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 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 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
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.
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.
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 mole cricket, an
insect belonging to the Gryllotalpidaefamily. Mole crickets are common insects, found on every continent except
Antarctica, but because they are
nocturnal and spend nearly all their lives underground in extensive tunnel systems, they are rarely seen. This specimen is likely to be Gryllotalpa brachyptera and is about 3.5 cm (1.4 in.) in size.
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.
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.
A male Roesel's bush-cricket (Metrioptera roeseli), a European
bush-cricket named after
August Johann Rösel von Rosenhof, a German
entomologist. Its song is very similar to that of
Savi's Warbler. Its body length as an adult insect is 15 to 18 mm. It is brown with a pale margin to the sides of the
pronotum. Its forewings usually reach midway along its abdomen at rest. However there is a
macropterous form of this insect (f. diluta), in which the wings reach beyond the tip of the abdomen. This form appears predominantly during hot summers and enables the species to extend its geographical range rapidly while conditions are suitable; such migrations may also be in response to local overpopulation.
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 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 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.
Two flesh-flies (Sarcophaga ruficornis species pictured) mating. The
life cycle of the
saprophagic flesh-fly
larvae has been well researched and is very predictable. Different species prefer bodies in different states of
decomposition, which allows
forensic entomologists to extrapolate the time of death.
The 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.
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