Red-headed Mouse Spider

Details

The Red-headed Mouse Spider (Missulena occatoria) is a large Australian mouse spider in the family Actinopodidae. Males are easily recognised by their bright red cephalothorax and striking blue-black abdomen, making this one of the most conspicuous mouse spider species.

Basic Biology

• Scientific name: Missulena occatoria

• Common name: Red-headed Mouse Spider

• Family & genus: Actinopodidae, genus Missulena

• Size: Females reach a body length of about 20–24 mm or more and are stout, short-legged spiders; males are smaller,      around 10–15 mm in body length with relatively longer, slimmer legs.

• Longevity: Females are thought to live many years in their burrows (around 8–10+ years), whereas males typically survive      only months to a few years after reaching maturity.

Appearance

Red-headed Mouse Spiders have the characteristic bulbous head and massive jaws typical of mouse spiders, and are often mistaken for funnel-web spiders by non-specialists.

• Males: Bright red cephalothorax and jaws with a dark blue to blue-black abdomen, giving a vivid two-tone appearance;

• Females: Robust spiders, mostly dark brown to black with little or no red, and very strong fangs;

• As mygalomorph spiders, their fangs strike downwards in a parallel motion rather than crossing like those of most house spiders.

Distribution & Habitat

Missulena occatoria is one of the most widely distributed mouse spider species. It occurs across much of mainland Australia, from open forest through woodland and grassland to semi-arid shrubland, and is especially common in parts of New South Wales and Western Australia.

Typical habitats include:

• Soil banks and levees along rivers, creeks and drainage lines;

• Open woodland and scrub, road verges and farmland edges;

• Suburban gardens and lawns on the fringes of towns and cities.

Burrows & Behaviour

Red-headed Mouse Spiders dig deep, silk-lined burrows in the ground, sometimes extending 30–55 cm below the surface. Many burrows have two trapdoor-like lids or reinforced flaps that help conceal the entrance and provide an escape route.

Females spend most of their lives in and around the burrow entrance, ambushing passing prey. Adult males leave their burrows androam during late summer to winter, particularly after rain, searching for females. This wandering behaviour is when people are most likely to encounter them.

Diet & Ecological Role

Red-headed Mouse Spiders are nocturnal sit-and-wait predators that feed on:

• Ground-dwelling insects such as beetles, cockroaches and crickets;

• Other spiders and arthropods caught near the burrow;

• Occasionally small vertebrates like lizards or frogs.

They help regulate populations of invertebrates in their habitats, while themselves providing food for birds, small mammals and reptiles.

Venom & Medical Significance

The venom of mouse spiders, including the Red-headed Mouse Spider, contains potent neurotoxic components and in laboratory studies shows similarities to Australian funnel-web spider venom. In theory, bites can cause serious systemic effects.

However, clinical reviews of confirmed mouse spider bites indicate that most cases cause only mild to moderate symptoms, with severe envenoming being rare and no deaths documented. In the uncommon situations where significant toxicity occurs, doctors in Australia may use funnel-web spider antivenom, which appears to be effective for serious mouse spider bites.

Human Encounters & Precautions

Because males wander on the surface, especially after rain, people may encounter Red-headed Mouse Spiders on tracks, lawns or garden beds. Practical precautions include:

• Wearing sturdy gloves and closed footwear when gardening or moving rocks, logs or building materials;

• Avoiding putting bare hands into holes, cracks or leaf litter where spiders may be hiding;

• Using a jar and stiff card, or long-handled tools, to safely contain spiders if removal is necessary, rather than handling them directly.

Any suspected bite from a mouse spider in Australia should be assessed promptly by medical staff, and first-aid procedures similar to those for funnel-web spiders may be advised.

References

Brunet, B. 2008. Spider Watch: A guide to Australian spiders. Reed New Holland.

Simon-Brunet, B. 1994. The Silken Web: a natural history of Australian Spiders.Reed Books.

Sutherland, S.K. & Nolch, G. 2000. Dangerous Australian Animals. Hyland House.

York Main, B. 1976. Spiders. Australian Naturalist Library, Sydney.