
Thursday 15 February
The World's Favourite Unloved Species 2018 - the Galapagos Racer
Kingdom | Animalia |
Phylum | Arthropoda |
Class | Arachnida |
Order | Araneae |
Family | Araneidae |
Genus | Austracantha (1) |
The Australian jewel spider (Austracantha minax) belongs to the distinctive orb-weaver family, and is beautifully ornamented with spines and circular impressions on the abdomen (3). As in all spiders the body is divided into two parts, the cephalothorax and the abdomen, and on each side of the mouth are venom-injecting fangs and leg-like pedipalps (4).
Spiders of the Austracantha genus have brightly coloured abdomens, usually red, yellow or white, the patterns of which deter predators such as birds. As in other members of its genus, female Australian jewel spiders have a hard body (5), with yellow and white patterning and a series of black spines. However, the melanic female morph is often completely black (6). Male orb-weaver spiders, including the Australian jewel spider, are smaller with a more cylindrical abdomen (5), and have a colourful yellow, white, brown and black body with smaller spines compared to the female. Both sexes have six spines that extend from the end of the abdomen (6).
There are five recognised subspecies of the Australian jewel spider (1).
The Australian jewel spider builds its orb-shaped web from silk (2), placing silky ‘tufts’ on specific threads as it does so (7). All spiders are predatory and carnivorous, feeding by injecting venom into their insect prey (8). As an opportunistic feeder, the Australian jewel spider has a web which is extremely well adapted to catch flying insects (9).
Female and juvenile Australian jewel spiders spin orb webs solitarily or occasionally in groups, which are known as ‘facultative aggregations’. The potential advantages of facultative aggregations are increased protection from predators, increased prey capture, and greater mate choice for females. Associated costs can include increased parasitism of egg cases. The collective webs of the Australian jewel spider are often made up of up to 30 individual webs that are joined together by shared support threads (2).
When courting a female, the male Australian jewel spider begins by building a ‘mating thread’ from the vegetation to the edge of the female’s web, and strumming it using the first and second pair of legs. The female spider is enticed onto the mating thread by the strumming, and is then tightly embraced by the male, who passes sperm to the female’s external genital structure via a pedipalp (10). The male Australian jewel spider will defend the female following mating, ceasing only when the female is no longer receptive to mating (11).
The variably shaped egg sacs of the Australian jewel spider are reddish-brown, and are usually found attached to a twig, close to the web (6). Australian jewel spiderlings pass through the Australian winter season within the camouflaged egg sacs, emerging in early spring. Male spiders reach maturity by mid-December whereas females mature later, in mid-January (2).
The Australian jewel spider is widespread throughout Australia (2).
The Australian jewel spider is not yet classified on the IUCN Red List.
There are no known threats to the Australian jewel spider at present.
No conservation actions are known to currently involve the Australian jewel spider.
Find out more about the Australian jewel spider:
For more information on conservation in Australia:
This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:
arkive@wildscreen.org.uk
Image credit
© Steven David Miller / Auscape International
Auscape International
PO Box 1024,
Bowral
NSW
25a76
Australia
Tel: (+61) 2 4885 2245
Fax: (+61) 2 4885 2715
sales@auscape.com.au
http://www.auscape.com.au
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Thursday 15 February
The World's Favourite Unloved Species 2018 - the Galapagos Racer
Thursday 01 February
Thursday 01 February