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Zygoballus rufipes, commonly called the hammerjawed jumper, is a species of jumping spider which occurs in the United States, Canada, and Central America. Adult females are 4.3 to 6 mm in body length, while males are 3 to 4 mm.

Taxonomy

Female
The species was first described in 1885 by George and Elizabeth Peckham from a specimen in Guatemala. The Peckhams subsequently described the northern variant as a separate species, Z. bettini, in 1888. In 1980, after examining specimens of Z. bettini and Z. rufipes from various populations, G. B. Edwards concluded that the differences mentioned by the Peckhams were not consistently distinct and that the two names represented a single species of variable appearance. The two names were therefore synonymized. The genus Zygoballus is currently classified in the subfamily Dendryphantinae of the family Salticidae (jumping spiders).

Distribution

Zygoballus rufipes has been reported from Canada, the United States, Mexico, Guatemala, and Costa Rica. In 1929, entomologist Nathan Banks reported a female specimen from Panama. In 1946, however, arachnologist Arthur M. Chickering concluded that Banks' specimen belonged to the newly described species, Zygoballus optatus. Chickering himself found no specimens of Z. rufipes in Panama after collecting there for several years. A one-year survey of Panamanian spiders conducted by zoologist Wolfgang Nentwig also failed to yield the species.


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Zoropsidae is a family of uncommon, somewhat wolf spider-like, wandering, cribellate spiders. They are also called false wolf spiders, because of their similarities to wolf spiders. The eye arrangement is not like that of wolf spiders as the eyes are in two rows and are more equal in size. They include about 180 species in 25 genera. One species, Zoropsis spinimana, was accidentally introduced to the United States.

The family Tengellidae is now included in Zoropsidae.

Genera

As of November 2015, the World Spider Catalog accepted the following genera:

Akamasia Bosselaers, 2002
Anachemmis Chamberlin, 1919
Austrotengella Raven, 2012
Birrana Raven & Stumkat, 2005
Cauquenia Piacentini, Ramírez & Silva, 2013
Ciniflella Mello-Leitão, 1921
Devendra Lehtinen, 1967
Griswoldia Dippenaar-Schoeman & Jocqué, 1997
Huntia Gray & Thompson, 2001
Itatiaya Mello-Leitão, 1915
Kilyana Raven & Stumkat, 2005
Krukt Raven & Stumkat, 2005
Lauricius Simon, 1888
Liocranoides Keyserling, 1881
Megateg Raven & Stumkat, 2005
Phanotea Simon, 1896
Pseudoctenus Caporiacco, 1949
Socalchemmis Platnick & Ubick, 2001
Takeoa Lehtinen, 1967
Tengella Dahl, 1901
Titiotus Simon, 1897
Uliodon L. Koch, 1873
Wiltona Koçak & Kemal, 2008
Zorocrates Simon, 1888
Zoropsis Simon, 1878

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The zebra spider back spider (Salticus scenicus) is a common jumping spider of the Northern Hemisphere. Like other jumping spiders, it does not build a web. It uses its four pairs of large eyes to locate prey and its jumping ability to pounce and capture it. Zebra spiders are often noted for their awareness of humans. Upon noticing someone observing them, they can be seen raising their head, and usually change behavior (hence the name Salticus scenicus, theatrical jumper).

Description

Female zebra spiders are 5-9 mm long and males are 5-6 mm. The most distinctive feature of these spiders is their six very large eyes, which is typical for jumping spiders. Although they have eight eyes, the six at the front are the largest and give them excellent binocular vision. These tiny spiders are black with white hairs that form stripes.

Distribution

Zebra spiders are widespread across Britain, Europe, and North America, and are found throughout the Holarctic. They often live close to or in human settlements. They can be found on walls, plants and fences on sunny days; and also indoors on window sills, often in the corner behind curtains.

Behavior

S. scenicus eating Sitticus pubescens
Zebra spiders tend to hunt smaller spiders and similar insects. They have been observed feeding on mosquitos that are almost twice their length. They have also been observed taking on prey items up to 3 times the length of the spider, such as some of the smaller species of moth. Like other jumping spiders, these spiders use their large front eyes to locate and stalk their prey. They move slowly towards their prey until they are close enough to pounce on top of their victim, and their hunting behaviour has been described as cat-like. Using their acute eyesight, they are able to accurately judge the distances they need to jump.

They orient towards prey detected by its lateral eyes whenever the angle subtended by such prey exceeds 5.5°. The velocity of the prey is not involved in the determination of reactive distance, but only moving objects elicit orientation. The probability that orientation is followed by stalking is a function of both prey size and velocity. The zebra spider's stalk velocity declines progressively as it nears its (stationary) prey.

Before jumping, they glue a silk thread to the surface that they are jumping from so that if they miss the target, they can climb up the thread and try again - However, they may 'abseil' with a silk thread if they wish to descend from a height safely, for instance they have been documented 'abseiling' from ceilings. They ignore unappetising insects such as ants.

There are no extensor muscles at the 'hinge joints' of the spider leg, instead joints extension is due to the haemocoelic blood pressure in the leg. The most significant evidence that this extension is due to hydraulic forces is that the leg spines become erect during the jump, a result of increased body pressure which can be demonstrated on many spiders. The zebra spider's jump is almost entirely due to the sudden straightening of the fourth pair of legs. The mean jumping velocity is estimated to be between 0.64–0.79 m/s (2.1–2.6 ft/s).

When these spiders meet, the male carries out a courtship dance involving waving his front legs and moving his abdomen up and down. The better the dance the more likely the female will want to mate, with success guaranteed if the male can exhibit a perfect shuffle.[citation needed] Females will stay with their egg sacs and will guard the young after they hatch. After the spiderlings have had their second moult they will leave the mother and fend for themselves.

Taxonomic history

External identifiers for Salticus scenicus
Encyclopedia of Life 1214203
NCBI 243486
WoRMS 231976
Also found in: Wikispecies
Salticus scenicus was one of the spiders included in Carl Alexander Clerck's 1757 work Svenska Spindlar / Aranei Suecici, the starting point for spider names in zoological nomenclature. Clerck originally called the species Araneus scenicus, and Carl Linnaeus, in the 1758 edition of Systema Naturae named it Aranea scenica; the specific epithet scenicus means "actor". Since then a number of synonyms have been published:

Araneus scenicus
Aranea scenica
Aranea albo-fasciata
Aranea fulvata
Attus scenicus
Attus candefactus
Epiblemum faustum
Attus scenicoides
Calliethera histrionica
Calliethera scenica
Calliethera aulica
Salticus albovittatus
Attus histrionicus
Callithera alpina
Callietherus histrionicus
Epiblemum histrionicum
Salticus histrionicus
Epiblemum scenicum
Calliethera goberti
Calliethera albovittata

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Xysticus is a genus of ground crab spiders described by C. L. Koch in 1835, belonging to the order Araneae, family Thomisidae. The genus name is derived from the Ancient Greek root xyst, meaning "scraped, scraper".

Distribution

The genus Xysticus is distributed almost worldwide, but has not been recorded from South America. Of the about 360 species of the genus currently described, about 71 are present in Europe.

Description

Xysticus and Coriarachne are dark brown or reddish-brown crab spiders often encountered on weeds or trees. While similar to the 'flower spiders', they tend to have shorter, sturdier legs. Many, but not all, species have abdomens more patterned than most Thomisus species, rather like some of the Synema species. Some however, that are more terrestrial, resemble earth in colour and texture.


A ground crab spider with earthy coloration
Most species of the genus Xysticus are small to medium sized spiders. They show a sexual dimorphism in size. Females of typical species reach a maximum of 10 millimetres (0.39 in) of body length, while their males are about 3–5 millimetres (0.12–0.20 in) long, about half the size of the females.

The basic colour of these species is usually brown, beige or gray. The prosoma is sometimes slightly smaller than the opisthosoma. In many species the front body shows in the middle a broad, pale longitudinal band. The opisthosoma is clearly flattened in most species and shows a median broad and dark leaf marking.

The species are often very similar to each other, and in most cases can be distinguished only by a microscopic examination of the reproductive organs.

Behaviour

The spiders of the genus Xysticus do not build webs; like most Thomisidae they are ambush hunters and prefer to hunt near the ground (hence the common name "ground crab spiders"). They move slowly, and commonly hunt by stationing themselves in a high-traffic area and grabbing whatever arthropod passes close enough. Also like most other Thomisidae, they seize prey with their enlarged anterior two pairs of legs and kill it by a venomous bite.


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The woodlouse spider, Dysdera crocata, is a species of spider that preys exclusively upon woodlice. Other common names refer to variations on the common name of its prey, including woodlouse hunter, sowbug hunter, sowbug killer, pillbug hunter and slater spider.

Appearance

Female specimens are 15–30 mm long, while males are 10–15 mm. They have six eyes, a dark-red cephalothorax and legs, and a shiny (sometimes very shiny) yellow-brown abdomen. Notably, they have disproportionately large chelicerae. Dysdera crocata is difficult to distinguish from the much less common Dysdera erythrina though this species is not often found near human habitation.

Distribution

D. crocata, which originated in the Mediterranean area, now has a cosmopolitan distribution (see map).

Behavior

Woodlouse spiders are usually to be found under logs in warm places, often close to woodlice. They have been found in houses. They spend the day in a silken retreat made to enclose crevices in, generally, partially decayed wood, but sometimes construct tent-like structures in indents of various large rocks. Woodlouse spiders hunt at night without the use of a web.

Male Dysdera crocata
Their diet consists exclusively of woodlice which—despite their tough exoskeleton—are pierced easily by the spider's large chelicerae; the spider is able to inject venom into the woodlouse's soft underbelly while avoiding any noxious defensive chemicals. Laboratory experiments have shown D. crocata will take other invertebrates, and shows no particular preference for slaters; these are simply the dominant prey in its habitat.

The courtship of these spiders is typically aggressive and mates risk injury from each other's large chelicerae. The female lays her eggs in a silken sac and is believed to look after her young after hatching like the "Mothercare" spider (Theridion sisyphium).

They have been known to bite humans if handled. Their bite is less painful than a bee sting and the venom causes no major medical problems. Localized itchiness at the bite site has been reported in some cases.


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The wheel spider or golden wheel spider (Carparachne aureoflava), is a huntsman spider native to the Namib Desert of Southern Africa. This spider should not be confused with Leucorchestris arenicola, a spider sharing the same common name as well as the same locale. The spider escapes parasitic pompilid wasps by flipping onto its side and cartwheeling down sand dunes at speeds of up to 44 turns per second.

Wheel spiders are up to 20 mm in size, with males and females the same size. The wheel spider is a nocturnal, free-ranging hunter, coming out at night to prey on insects and other small invertebrates. Its bite is mildly venomous, but the spider is not known to be harmful to humans.

A Wheel Spider burrow.
A Wheel Spider burrow.
The wheel spider does not produce a web. Its principal line of defence against predation is to bury itself in a silk-lined burrow extending 40–50 cm deep. During the process of digging its burrow, the spider can shift up to 10 litres of sand, 80,000 times its body weight. It is during the initial stages of building a burrow that the spider is vulnerable to pompilid wasps, which will sting and paralyze the spider before planting eggs in its body. If the spider is unable to fight off a wasp, and if it is on a sloped dune, it will use its rolling speed of 1 metre per second to escape.


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