Sparassidae

What is Sparassidae?

Huntsman spiders, scientifically classified within the family Sparassidae (formerly Heteropodidae), are a diverse group of arachnids renowned for their speed and hunting prowess. Unlike many other spider families, they do not construct webs to capture prey. Instead, they actively pursue and hunt their food, which primarily consists of insects and other invertebrates, though larger species may occasionally prey on small vertebrates like lizards and geckos. Their common names, such as "giant crab spiders" or "wood spiders," reflect their considerable size and their preference for woody habitats like forests, mine shafts, and woodpiles.

Distribution and Habitat

Members of the Sparassidae family are found in most warm, temperate, and tropical regions across the globe. Their natural range includes much of Australia, Africa, Asia, the Mediterranean Basin, and the Americas. While many species inhabit warmer climates, some, like the green huntsman spider (Micrommata virescens), are native to colder regions such as Northern and Central Europe. They typically reside under rocks, bark, and similar sheltered locations, but are frequently encountered by humans in sheds, garages, and other human-made structures that are not frequently disturbed.

Description and Identification

Sparassids are characterized by their eight eyes, arranged in two forward-facing rows of four. They are often mistaken for tarantulas due to their hairy appearance and size, but can be distinguished by their legs. Rather than being held vertically, their legs are twisted, allowing them to extend forward in a manner reminiscent of a crab. This "crab-like" posture is a key identifier. Many species are large, with some males of the giant huntsman spider (Heteropoda maxima) achieving leg spans of up to 30 cm (11.8 inches). Their coloration is typically subdued, with upper surfaces in shades of brown or grey, while undersides may be marked with contrasting black and white patterns. Their legs are often spiny.

Behavior and Reproduction

These spiders are known for their remarkable speed and agility, often employing a springing jump while running and capable of traversing walls and ceilings. Females are particularly known for their fierce defense of their egg sacs and young, often exhibiting threat displays when provoked. Egg sac carrying varies by genus; some females carry them under their bodies, while others attach them to vegetation. Interestingly, some male huntsman spiders, such as those in the genus Heteropoda, have been observed to produce vibrations transmitted through surfaces as a form of substrate-borne sound, used to attract females for mating. This sound can sometimes be heard by humans as a rhythmic ticking.

Venom and Significance

Like most spiders, Sparassidae utilize venom to subdue their prey. While their venom is effective for their hunting purposes, bites to humans are generally not considered medically significant and rarely require professional medical attention. However, some species, particularly from genera like Palystes and Neosparassus, have been reported to inflict bites causing localized swelling, pain, and in more severe cases, systemic symptoms like nausea, headache, and palpitations. It is important to note that the study of spider bites is complex, with factors like infection, shock, and misidentification potentially influencing outcomes.