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Missulena occatoria (Family Actinopodidae)

Red-headed Mouse Spider

Distribution

Distribution:

This species is found across much of mainland Australia (especially inland areas) in a range of habitats, varying from open forest to desert shrublands. Spiders in the genus Missulena occur only in Australia; they are most closely related to species in two South American genera, and thus part of Gondwanan fauna. (NSW, QLD, VIC, SA, WA, NT)

Features:

The Red-headed Mouse Spider is the largest and most widely distributed of the Missulena species. It is one of the mygalomorphs, in which the jaws move up and down in line with the body. The squat, short-legged females are 15 to 24 mm in body length and black all over, although their bulbous head and powerful jaws may have a reddish tinges. The eyes are spread across the front of the head region.portion of the body or carapace. The smaller males, 6 to12 mm body length, are longer-legged and strikingly coloured, with a bright red head and jaws, and a gunmetal blue-black abdomen.

Ecology/Way of Life:

Red-headed Mouse Spiders occur widely, because their young use the wind to travel over large distances. Each spiderling lets out a long silk thread, which is caught in the breeze and carries the young spider with it. In autumn and early winter, spiderlings emerge in large numbers from their burrow and climb into trees or onto fences, to take to the air on their long silk thread. This technique, called ballooning, is rare in mygalomorph spiders, in which the young usually disperse by walking.

The silk-lined burrow of these spiders has two entrance trapdoors close to each other. It is 20 to 55 centimetres deep and is widest in the entrance and bottom chamber areas. The twin silk and soil trapdoors may be thin and wafer-like or thick and plug-like. They often merge well with the ground, making the burrow hard to find. The adult female places her egg sac (containing about 50 eggs) within a side chamber, which opens through a vertically hinged door about halfway down the burrow.

These two surface doors increase both prey catching area and door handling efficiency. A few silk triplines extend outwards from the entrance. They can alert the spider to approaching prey or possible mates, and also help with navigation on the surface while hunting. Prey is usually ambushed from within the safety of the trapdoor "hides", although mouse spiders may forage outside the burrow at night. With their powerful jaws and venom, they can tackle prey ranging from ants, beetles and spiders to small lizards and frogs.

During autumn and winter mature male spiders leave from their burrow to search for females. They are unusual, in that they wander by day, their striking colouration presumably acting to deter predators. The long pedipalps of the male are held extended forwards; attached on each side of the jaws, these long structures bear the mating organs, and are thought to detect the airborne scent, or pheromone, associated with the female or its burrow. Once a burrow is reached the male taps the ground and silk around the doors until the female emerges. If she is receptive the male follows her into the burrow where mating occurs.

Having two smaller doors rather than one bigger door both increases prey catching area and door handling efficiency. A few silk triplines may extend outwards from the entrances. These can alert the spider to approaching prey or mates and also help with surface navigation while hunting. Prey is usually ambushed from within the safety of the trapdoor "hides", but mouse spiders have been observed foraging outside the burrow at night. With their powerful jaws and venom, they can tackle prey ranging from ants, beetles and spiders to small lizards and frogs.

Preferred Image

Interaction with Humans/Threats:

Female mouse spiders tend to remain in or near their burrows throughout their life. Males wander, especially after autumn/winter rains, and will take on a threatening posture if disturbed. Though sluggish and rarely aggressive, they produce lots of a very toxic venom, which is potentially as dangerous as that of the Sydney Funnel-web Spider. Males wander during early winter, especially after rain, and will take on a threatening posture if disturbed. The only case of serious envenomation resulted from the bite of a male Eastern Mouse Spider, Missulena bradleyi near Brisbane. Although males are often sighted, bites by Red-headed Mouse Spiders are rare, probably because they occur mostly in less densely populated inland areas, thus reducing the potential hazard for humans. Evidence indicates that mouse spider venom is potentially as toxic to humans as funnel-web spider venom - first aid and medical treatment is as recommended for funnel-web spider envenomation.

Other Comments:

The Red-headed Mouse Spider was described by Walckenaer in 1805. The basis for the genus and species names has yet to be determined.

Further Reading:

Faulder, R.J. (1995). Systematics and biogeography of the spider genus Missulena Walckaener. Thesis (M.Sc.Agr.), University of Sydney.

Main, B.Y. (1953). Observations on the burrow and natural history of the trap-door spider Missulena (Ctenizidae). Western Australian Naturalist 5 (4): 73-80.

Sutherland, S. and G. Nolch (2000). Dangerous Australian Animals. Hyland Press.

Topics:

Silk Gondwana Spider webs Venom Prey capture

Acknowledgments:

Text & map by Mike Gray; photographs by Mike Gray, courtesy of the Australian Museum.

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Images and Multi-media:  
Attached Image  
image/jpeg 30553 bytes Missulena occatoria female
Attached Image  
image/jpeg 26579 bytes Missulena occatoria male
Distribution Map  
image/jpeg 25359 bytes Missulena occatoria map

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