The Sydney Funnel-Web Spider, as it is commonly referred to, is a member of the Arachnids, which most people recognize as the spiders, but this group actually includes the scorpions and other related organisms as well. You will find detailed information on its taxonomic classification further down on this page. The Latin scientific name of the Sydney Funnel-Web is Atrax robustus, which translates to "Dark hardy", an apt description of the species' two most obvious characteristics. These two traits are clear in this image of a Sydney Funnel-web.
The full classification of Atrax robustus is presented here, first as a step-by-step explanation of its placement at each taxonomic level, followed by a diagram illustrating its relationship with its relatives. Because of the size of this diagram, it is presented on a separate page . The Three-Domain System was developed using rRNA (ribosomal RNA), but all the other strata are based on morphology. (Freeman 9) The step-by-step explanation includes all the groups that I could find that A. robustus fits into, whereas the tree diagram is exorbitantly abridged. If I were to have included all the groups relative to A. robustus, even though they are only a fraction of the Tree of Life, the diagram would have been enormous!
The presence of cell nuclei distinguishes the cells of Atrax robustus from those of the Archaea and the Prokarya. (Freeman 9, 131)
As is characteristic of the animals, Atrax robustus is mobile, heterotrophic, and multicellular. (Freeman 698)
Meaning "truly-among-animals". This group includes all animals except the sponges; all animals which have true tissues. (Freeman 700)
These animals are bilaterally symmetrical at some point in their life cycles. (Freeman 704, 707)
In these animals, the mouth appears before the anus during development, cleavage is spiral and determinate, and the coelom forms as a splitting of the mesoderm. (Freeman 704-705, 707)
Atrax robustus exhibits a segmented body, chitinous exoskeleton, and jointed, paired appendages. (Freeman 707, 743)
This group is characterized by the presence of an anterior cephalothorax and a posterior abdomen. They have six pairs of appendages, which include the chelicerae, for which the group is named. (Freeman 743), (Savory 4)
Members of this class, which includes the scorpions as well as the spiders, generally have six pairs of appendages. Four of these pairs tend to function as legs, for a total of eight legs, with the fifth and sixth pairs adapted for use in feeding, defense, and sensory perception. A key diagnostic feature of this class is the absence of antennae and wings exhibited by its members. (Savory 9-11)
As a member of this order, Atrax robustus has two body segments, or tagmata, eight legs, no chewing mouth parts, and no wings. Like all spiders, it is capable of producing silk. (Savory 164), (Kaston 14-15)
This group encompasses two families: Mygalomorphae and Araneomorphae. Basically, it includes all spiders except for the primitive family Mesothelae. Atrax robustus belongs to the family Mygalomorphae, which is described below. (Kaston 29)
This group consists of the thicker, stouter spiders, whose fangs are long and point strait down, as opposed to those of the Araneomorphans, which cross each other. The group includes the trapdoors, funnel-webs, and tarantulas. Like the Araneomorphans, these spiders are capable of injecting venom for food acquisition and self defense. (Preston-Mafham 23-24, 41), (Bug Guide.net)
The characteristics of this group are the same as those of the family Hexathelidae (see below), because this group includes only that family. It exists essentially as a place to harbor this family so that it is not incorrectly dumped into one of the other superfamilies that actually encompass more than one family. (Texas A&M)
The members of this family are known as the funnel-web tarantulas. They are larger spiders, ranging from one to five centimeters in length, and are typically colored in shades of black and brown. A distinctive feature of this family is the glossy carapace (hard covering) over the front part of the body (cephalothorax). These spiders also have relatively large spinnerets (silk producing organs). (Texas A&M), (ZipCodeZoo)
Members of genus Atrax are known as the funnel-webs, spinning funnel-shaped webs in crevices, under rocks, or among plants. Males have mating spurs located midway along their second legs. These spiders are glossy brown and black. (Australian Venom Compendium)
Species: Atrax robustus
Members of this species, better known as Sydney Funnel-Webs, occur only in the vicinity of Sydney, Australia, as their name suggests. They are very large, ranging from six to seven centimeters, and are capable of injecting a venom primarily composed of a neurotoxin known as Atraxotoxin, which has dramatic effects on primates (apes, humans), but has negligible effects on other animals such as cats and toads. Males, which are five times more venomous than females, tend to wander from their burrows and crevices at night in Summer and Autumn in search of females for breeding (more info in ). They feed by attacking creatures that disturb trip lines of silk which they lay outside their burrows, dragging the immobilized prey back into their burrows for consumption. (InChem.org), (Australian Museum Online), (ThinkQuest.org)
Here's another link to my diagram of A. robustus' taxonomy just in case you missed the link at the top of this page!
This site was last updated 04/25/08