''Atrax'' is a genus of venomous Australian funnel web spiders that was first described by

O. Pickard-Cambridge Octavius Pickard-Cambridge FRS (3 November 1828 – 9 March 1917) was an English clergyman and zoologist. He was a keen arachnologist who described and named more than 900 species of spider. Life and work Pickard-Cambridge was born in Blox ...

in 1877 from the type species '' Atrax robustus''. it contains only three species: ''A. robustus'', '' A. sutherlandi'', and '' A. yorkmainorum''. Originally placed with the curtain web spiders, it was moved to the Hexathelidae in 1980, then to the

Australian funnel-web spider Atracidae is a family of mygalomorph spiders, commonly known as Australian funnel-web spiders or atracids. It has been included as a subfamily of the Hexathelidae, but is now recognized as a separate family. All members of the family are native to ...

s in 2018.

Description

They are medium to large spiders for their family, ranging from 1.5 to 4.5 cm. As most in the Mygalomorphae infraorder, they have robust bodies, with a glossy dark colouration in their

carapace A carapace is a Dorsum (biology), dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tor ...

and legs, and a grey opisthosoma. They also have the same long life, ranging from 4 to 20 years. They are usually found in

burrow An Eastern chipmunk at the entrance of its burrow A burrow is a hole or tunnel excavated into the ground by an animal to construct a space suitable for habitation or temporary refuge, or as a byproduct of locomotion. Burrows provide a form of sh ...

s with little silk lining, under rocks or logs, with their aptly named funnel-like webs. They are found in the coasts and highlands of southeastern

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

Identification

They can be identified from others of the same family by the large coniform apophysis on the male tibia, and from the

Hadronyche ''Hadronyche'' is a genus of venomous Australian funnel-web spiders that was first described by L. Koch in 1873. Originally placed with the curtain web spiders, it was moved to the Hexathelidae in 1980, then to the Atracidae in 2018. Descript ...

by the lower caput height, caput being the front part of the

cephalothorax The cephalothorax, also called prosoma in some groups, is a tagma of various arthropods, comprising the head and the thorax fused together, as distinct from the abdomen behind. (The terms ''prosoma'' and ''opisthosoma'' are equivalent to ''cepha ...

Venom

This genus includes some of the most dangerous spiders, namely the Sydney funnel-web spider (''Atrax robustus).'' This spider is thought to have killed 13 people. Though none have died since the anti venom has been introduced, many consider this spider to be quite dangerous, and deadly. Most of the bites are thought to be caused by male spiders which wander out of their hides to find a mate.

Hides

These spiders usually make their

s under rocks or logs, usually in cool humid areas. They make funnel shaped webs, with silk trip lines that radiate from the entrance. These lines function as a warning system, which tell the spiders if there is an insect or possible mate coming. Their hides might flood, forcing them to leave their hides, although they can last a few hours in water, as they are able to trap air bubbles in their abdomen using hairs. They may also leave their burrow to find a mate.

Phylogeography

Phylogeography can be understood as the historical changes or occurrences that bring about a change to a specific species or organism. After extensive studies, researches have found that there are many geographical and genetic differences that have occurred due to micro-habitat distributions. The assumption has been made that the species of ''Atrax'' have experienced a shift in genetic structure due to the niches that they inhabit. Habitats are not the only factor to this divergence; researchers have also noted the climatic events, prey availability, and natural occurrence of biodiversity.

References

External links

{{Authority control Atracidae Mygalomorphae genera Spiders of Australia