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!
Domain: Eukarya
The presence of cell nuclei distinguishes the cells of Atrax robustus from those of the Archaea and the Prokarya. (Freeman 9, 131)
Kingdom: Animalia
As is characteristic of the animals, Atrax robustus is mobile, heterotrophic, and multicellular. (Freeman 698)
Subkingdom: Eumetazoa
Meaning "truly-among-animals". This group includes all animals except the sponges; all animals which have true tissues. (Freeman 700)
Infrakingdom: Bilateria
These animals are bilaterally symmetrical at some point in their life cycles. (Freeman 704, 707)
Superphylum: Protostomia
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)
Phylum: Arthropoda
Atrax robustus exhibits a segmented body, chitinous exoskeleton, and jointed, paired appendages. (Freeman 707, 743)
Subphylum: Chelicerata
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)
Class: Arachnida
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)
Order: Araneae
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)
Suborder: Opisthothelae
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)
Infraorder: Mygalomorphae
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)
Superfamily: Hexatheloidea
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)
Family: Hexathelidae
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)
Genus: Atrax
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!
