the Mysterious World of Australian Huntsman Spiders

Huntsman Spiders with egg sac

Exploring the Fascinating Lives of These Misunderstood Arachnids

Huntsman spiders, often referred to as “tarantulas” or “giant crab spiders,” are among the most interesting and feared arachnids in Australia. Belonging to the family Sparassidae (formerly Heteropodidae), these large, hairy spiders are known for their impressive size, unique appearance, and occasional encounters with humans in domestic settings.

Identification and Physical Characteristics

Australian Huntsman spiders are easily recognized by their large size and distinctive appearance. With body lengths reaching up to 2 cm for females and 1.6 cm for males, and an impressive leg span of up to 15 cm, these spiders are among the largest in Australia. Their bodies are typically grey to brown in color, with some species exhibiting banded legs.

One of the most striking features of Huntsman spiders is their flattened bodies, which are adapted for living in narrow spaces under loose bark or rock crevices. This is particularly evident in genera such as Delena, Isopeda, Isopedella, and Holconia. Their legs are also uniquely twisted, with joints that allow them to spread out forwards and laterally in a crab-like fashion, hence the common name “giant crab spiders.”

A Huntsman Spider in a Brisbane home

Habitat and Distribution

Huntsman spiders are found in a variety of habitats throughout Australia. They can be spotted living under loose bark on trees, in crevices on rock walls, in logs, under rocks and slabs of bark on the ground, and even on foliage. Some species, such as the social huntsman spider (Delena cancerides), are known to gather in large numbers under bark on dead trees and stumps, particularly wattles.

These spiders are also notorious for their tendency to enter human dwellings, often causing alarm when found hiding behind curtains or scuttling across walls. They are equally infamous for their surprise appearances in cars, hiding behind sun visors or running across dashboards.

While Huntsman spiders are widely distributed throughout Australia, some genera have more specific ranges. For example, Heteropoda is absent from most of Southeastern Australia, and Tasmania is home to only a few species, notably Delena cancerides and Neosparassus sp.

Feeding Habits and Diet

Huntsman spiders are skilled predators, feeding primarily on insects and other invertebrates. Their large size and powerful legs allow them to quickly pounce on and subdue their prey. These spiders are not known to build webs for catching food; instead, they actively hunt and forage for their meals.

Life History and Reproduction

The life history of Huntsman spiders is pretty cool, with some species exhibiting unique reproductive behaviors. In the genus Isopeda, for example, the female produces a flat, oval egg sac made of white, papery silk and lays up to 200 eggs. She then places the egg sac under bark or a rock and stands guard over it for about three weeks without eating. During this time, the female can be quite aggressive, rearing up in a defensive display if provoked.

Some Huntsman species, such as Delena, have a slightly different approach. The female lays a ground-sheet of silk upon which the egg sac is anchored while the eggs are laid into it. She then completes the egg sac, picks it up, and carries it with her, leaving the silk ground-sheet behind.

Incubation periods vary and are likely influenced by climatic conditions. In some cases, the female may moisten and tear the egg sac open to help her spiderlings emerge. The mother stays with the young for several weeks, during which time the spiderlings undergo several moults, hardening to a darker brown color before eventually dispersing.

The lifespan of most Huntsman species is about two years or more. As with all spiders, Huntsman spiders must moult in order to grow, and their discarded exoskeletons can often be mistaken for the original spider when found suspended on bark or in houses.

Breeding Behaviors and Social Interactions

Huntsman spiders exhibit intriguing courtship and breeding behaviors. In the genus Isopoda, male and female Huntsman spiders engage in a lengthy courtship ritual involving mutual caresses, with the male drumming his palps on the trunk of a tree. After this, the male inserts his palps into the female to fertilize her eggs.

Unlike some other spider species, the male Huntsman is rarely attacked by the female after mating. In fact, many Huntsman spiders are known to live peacefully together in large colonies. Some species even build silken retreats for egg-laying and moulting.

Predators and Threats

Despite their impressive size and hunting prowess, Huntsman spiders are not without predators. Birds, geckoes, Spider Wasps, nematode worms, and egg parasites such as wasps and flies all pose a threat to these arachnids.

Misconceptions and Danger to Humans

While Huntsman spiders may appear intimidating due to their size and rapid movements, they are generally not considered dangerous to humans. Their bites, although painful, are not known to cause severe or life-threatening symptoms. In the event of a bite, a cold pack may help relieve local pain, and medical attention should be sought if symptoms persist.

It is important to note that the fear and anxiety surrounding Huntsman spiders often stem from misconceptions and a lack of understanding. These spiders are not aggressive and will typically only bite if they feel threatened or are accidentally disturbed.

Australian Huntsman spiders are an important and integral part of the country’s diverse arachnid fauna. By understanding their biology, behavior, and ecological role, we can develop a greater appreciation for these misunderstood creatures and work to dispel the myths and fears that surround them.

From their unique physical adaptations to their intricate courtship rituals and social interactions, Huntsman spiders offer a glimpse into the complex and captivating world of arachnids. As we continue to study and learn about these remarkable spiders, we can foster a more informed and respectful relationship with the natural world and the incredible creatures that inhabit it.

So, the next time you encounter a Huntsman spider in your home or garden, take a moment to marvel at its beauty and adaptations, and remember that these arachnids are not the fearsome creatures they are often portrayed to be, but rather an essential and fascinating part of Australia’s rich biodiversity.