Animal Species:Triangular Spiders, Arkys sp.
Triangular spiders are brightly coloured, distinctive spiders. Their unusually shaped and brilliantly coloured and patterned abdomens make them stand out from the crowd.
As their common name suggests they have a very distinctive triangular or heart shaped abdomen that is often brightly coloured and patterned in a combination of red, yellow, orange, black or white. Their first two pairs of legs are enlarged, covered in spines and curved forward to catch prey. The last two pairs of legs are a lot shorter in comparison.
Males and females are very similar in colour, shape and size.
Triangular spiders have been placed in several different families since their original description and the debate is still continuing as to where they fit. They are currently placed in the Araneidae family.
Not all species in the Arkys genus are the brightly coloured triangular spiders. Other species in this genus include bird-dropping spiders, which mimic bird droppings in size, colour and shape.
Body length approx 6mm
Triangular spiders are found through out the Australasian region including Australia, Papua New Guinea, Indonesia and New Caledonia
They are found in a range of habitats throughout Australia, in particular the east coast of Australia. They are commonly found in eucalypt forests and woodlands, but can be found in gardens. They are often seen on trees, shrubs and on or under leaves.
Triangular spiders are also commonly found on plant regrowth after forest fires.
Most prevelant in summer
Feeding and Diet
Triangular spiders ambush their prey. They wait motionlessly on leaves with their front two pairs of legs widely seperated. When their prey passes by they caputre it. Their sit and wait prey capture behaviour is similar to how flower spiders catch their prey.
Triangular spiders feed on insects, mainly flies.
Other behaviours and adaptations
Triangular spiders are thought be to nocturnal but are also seen during the day.
Triangular spiders do not weave webs like other members of the Araneidae famliy, they only use their silk for their egg sacs and for weaving saftey-lines.
In late summer, females produce a small egg sac that can have up to 50 eggs.
Danger to humans and first aid
Are harmless to human beings
Main, B (1982) Notes on the reduced web, behaviour and prey of Arcys nitidiceps Simon (Araneidae) in South-Western Australia. Bull. Br. Arachnol. Soc: 5(9): 425-432
Louise Carter , Technical Officer