Invertebrates
Giant Huntsman Spider
Heteropoda maxima · also called huntsman spider, cave huntsman
The giant huntsman spider has the widest reach of any spider on Earth — a leg span the size of a dinner plate — and it lives, as far as anyone knows, only in the caves of Laos. Its relatives, the ordinary huntsman spiders, are the large, fast, flat spiders that startle people worldwide by appearing on a wall or a sun visor.
Overview
Heteropoda maxima, the giant huntsman, was described in 2001 from limestone caves in Khammouan Province, Laos, and has been found only in and around a handful of them. It may be a cave-adapted species with a naturally tiny range. The huntsman family as a whole (Sparassidae) is enormous and widespread, occupying tropical, subtropical, and warm-temperate regions across every continent except Antarctica, and reaching very high densities in Australia.
The largest by reach
The giant huntsman’s leg span reaches about 30 centimetres, the greatest of any spider, though its body is small — under 5 centimetres. The size is almost all in the legs, which are long, spiny, and angled forward and to the sides. By mass and bulk the goliath birdeater tarantula is larger, so the two species divide the “world’s biggest spider” title between reach and weight.
Built to run, not to trap
Huntsman spiders are active hunters and build no capture web. Their leg joints are rotated so the legs splay outward, giving a flat, crab-like stance (hence the alternative name “giant crab spiders”) that lets them:
- slip into narrow crevices under bark, in rock, and behind furniture,
- sprint sideways at speed without turning,
- and climb smooth vertical and overhead surfaces using dense adhesive foot hairs.
They rely on good vision and reflexes to run down insects, other spiders, and small lizards, seizing prey and subduing it with a bite and a mild venom.
Reproduction
A female huntsman lays her eggs in a flat, papery silk sac, which many species carry under the body or guard in a retreat, sometimes staying with the spiderlings for weeks after they hatch — unusually attentive parental care for a spider. Females can be aggressive in defence of an egg sac.
Status and living with huntsmen
The giant huntsman has not been formally assessed, but its apparent restriction to a few Laotian caves would make it inherently vulnerable to disturbance, quarrying, and tourism. The common huntsman species are secure and abundant. Their venom is not dangerous to people, they are reluctant to bite, and they are beneficial predators of household pests — the main “problem” they cause is being large, fast, and prone to turning up indoors.
Giant Huntsman Spider: common questions
Is the giant huntsman the biggest spider in the world?
It is the biggest by leg span — up to about 30 centimetres, roughly the size of a dinner plate. But it is not the heaviest or bulkiest — that title goes to the goliath birdeater, a South American tarantula with a body the size of a fist and a leg span a little smaller than the giant huntsman's. So the two share the "world's largest spider" claim, measured different ways — the huntsman for reach, the birdeater for mass.
Do huntsman spiders build webs?
No. Huntsmen are wandering hunters. They do not spin a capture web; instead they roam over tree bark, rock faces, walls, and ceilings, using excellent eyesight and speed to chase down and grab prey. They produce silk only to make a flat retreat under bark or a stone, to wrap an egg sac, and as a dragline. This is why a huntsman turns up walking across a wall or a car windscreen rather than hanging in a web.
Why do huntsman spiders run sideways so fast?
The leg joints of a huntsman are twisted so that the legs point forward and outward rather than straight down, giving the spider a low, flat, crab-like posture (they are sometimes called "giant crab spiders"). This lets it squeeze into narrow gaps under bark and behind furniture, and move at speed in any direction, especially sideways, without turning its body. Combined with adhesive foot hairs, it can sprint across smooth vertical and overhead surfaces.
Are huntsman spiders dangerous?
Not really. Huntsman venom is mild; a bite causes local pain, swelling, and sometimes nausea or a headache, but it is not medically significant for a healthy adult, and huntsmen are reluctant to bite, preferring to flee at high speed. They are, however, alarmingly large and quick, and in Australia the sudden appearance of a big huntsman indoors — often after it comes in to hunt insects or to shelter — is a common cause of panic. They are harmless housemates that eat cockroaches and mosquitoes.