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Abdomen: The second of the two main parts of the
body of a spider. |
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Araneomorph spiders: The more advanced spider
families, most of which can survive indefinitely in webs or other open
environments without suffering desiccation. |
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Book lungs: Small pocket-like openings on the underside of the
abdomen. The advanced (araneomorph) spider
families have one of these on each side of the abdomen close to its front
end but primitive spiders (mygalomorphs) have
a second pair behind the first. |
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Calamistrum: A comb of stiff hairs on the second last segment of the fourth pair of legs, used to comb silk from the web-spinning cribellum of some spiders. |
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Carapace: The hard upper 'shell' of the front
part of a spider. |
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Cephalothorax: The first of the two main parts
of the body of a spider. This part has the chelicerae with fangs attached, the pair of palps and the four pairs of legs
attached to it. |
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Chelicerae: A pair of short appendages at the front end of a spider. The
fangs are attached to these structures, which often contain the spider's venom glands as well. |
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Claw tuft: A thick brush-like set of hairs at the end of the legs of
some spiders. This is located just behind the tarsal claws. |
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Compression bandage: An elastic bandage that is wrapped around a limb
over a bite site with sufficient tension to slow, but not stop, the flow
of blood through the site. |
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Cribellum: A flat plate projecting backwards from the underside of the female abdomen of some spiders, used as a source of silk instead of one pair of spinnerets. In some families the silk-secreting part of this plate is divided into left and right halves. |
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Diaxial fangs: A pair of fangs that operate in pincer fashion. This
arrangement is found on araneomorph spiders. |
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Egg sac: A container or wad of spider silk that may contain and protect several hundred eggs
until they hatch. |
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Envenomation: Poisoning following the injection of a spider's venom into
the skin. |
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Epigastric furrow: A groove across the underside of the abdomen that marks the rear edge of the book lungs and the point of entry into the female genitalia. |
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Epigynum: The hardened, external mating structure found centrally on the
underside of the abdomen of a female spider just in front of the
epigastric furrow. It is easily seen on fully mature
araneomorphs but
not on mygalomorphs or immature araneomorphs. |
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Eye patterns: The set of four (or sometimes fewer) pairs of eyes found on the
caput, which is the somewhat raised front upper end of the
cephalothorax, just behind the fangs. These eyes are often arranged in two rows of four
so we refer to the front ones as the anterior median and lateral eyes (AME and ALE) and
the rear ones as the posterior median and lateral eyes (PME and PLE). |
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Fangs: Tapering curved needles used by a spider to inject its venom into
a victim. |
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Fovea: a short groove visible in the centre of the upper surface of the
carapace. This may be straight or curved and may run lengthwise or
across the carapace. |
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Instar: An immature form of a spider. In general, instars have some resemblance to the adult
female but they tend to have
different markings and their genitalia do not have a mature external appearance. |
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Moulting: When an immature spider breaks out of its hard body
shell to grow larger. This is the only way
they can mature to adulthood. Most spider species pass through
several instar sizes before becoming adults and some long-lived mygalomorph females are said to moult occasionally even after reaching adulthood. |
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Mygalomorph spiders: The more primitive spider families which
usually die quickly unless protected by a moist burrow. For this reason
they are mostly only active at night and during rainy periods. |
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Necrotising arachnidism: Progressive ulceration and loss of skin
around the site of a biting allegedly caused by a number of
araneomorph spider species. Note that there is only one Australian genus, Loxosceles, which is has been proven to
have this adverse effect on humans and it is very rare. The actual cause of the necrotizing phenomenon is uncertain and for this reason no fully effective
treatments are available in Australia at the present time.
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Neurotoxin: A nerve poison which is present in the venom of most
spiders and is used to immobilise prey. Only a small number of spider
species have neurotoxins potent enough to be life-threatening to humans.
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Palps: Short, leg-like structures attached to the front of the
cephalothorax between the fangs and the first
pair of conventional legs. In females and in immature males they resemble
small legs, although they have one less segment. In mature (or sometimes
nearly mature) males the terminal segments are modified into a bulb and needle
that are used for mating. |
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Paraxial fangs: A pair of fangs that strike downwards in parallel
arcs. This is the normal arrangement on a
mygalomorph spider. |
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Scopula: A dense brush of hairs on the underside of the terminal
segments of the legs of some spiders. |
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Sexual dimorphism: When the male and female of the same spider
species have physical characteristics so different that they appear not to
be the same species. This is most obvious when the spiders are mature.
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Spinnerets: These are the web-spinning organs found on the
underside of the abdomen at or near its rear end. There are at least two
pairs present and sometimes three. |
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Spur: A sharp thorn-like projection from a segment of a leg.
Spurs are much thicker and more tapering than the hairs found on the
legs of most spiders. |
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Tarsal bulb: The expanded end segment of the palps of a mature
male spider. This structure usually is like a bulb but has a hollow needle
(sometimes coiled) projecting backwards from it. |
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Tarsal claws: A pair of small claws at the end of each leg, used
by the spider to hold onto objects, including its own web. Many species
have a smaller median claw behind the main pair. |
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Tibia: The third segment of a spider's leg, counting inwards from
the outer end of the leg. |
