Huntsman spider facts for kids
Quick facts for kids Huntsman spider |
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| Huntsman spider | |
| Scientific classification | |
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Entelegynae
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| Superfamily: |
Sparassoidea
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Sparassidae
Bertkau, 1872
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Delena |
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| Diversity | |
| 82 genera, 1009 species | |
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Huntsman spider is a name given to the family Sparassidae (formerly Heteropodidae). They are also known as the giant crab spiders, due to the way they look. Larger ones, are also sometimes referred to as wood spiders, because they live in woody places (forest, mine shafts, woodpiles).
They are found in Australia, New Zealand, South Africa, Southeast Asia, the Mediterranean, Florida, and Hawaii, and possibly in many other tropical and semi-tropical regions. They can be found as far north as England, Sweden and Wales.
Huntsman spiders do not build webs, but hunt for food They eat insects and other invertebrates.
Contents
Appearance
Sparassids are eight-eyed spiders. The eyes appear in two largely forward-facing rows of four on the anterior aspect of the prosoma. Many species grow very large – in Laos, male giant huntsman spiders (Heteropoda maxima) attain a legspan of 25–30 centimetres (9.8–11.8 in). Persons unfamiliar with spider taxonomy commonly confuse large species with tarantulas, but huntsman spiders can generally be identified by their legs, which, rather than being jointed vertically relative to the body, are twisted in such a way that in some attitudes the legs extend forward in a crab-like fashion.
On their upper surfaces the main colours of huntsman spiders are inconspicuous shades of brown or grey, but many species have undersides more or less aposematically marked in black-and-white, with reddish patches over the mouthparts. Their legs bear fairly prominent spines, but the rest of their bodies are smoothly furry. They tend to live under rocks, bark and similar shelters, but human encounters are commonly in sheds, garages and other infrequently-disturbed places. The banded huntsman (Holconia) is large, grey to brown with striped bands on its legs. The badge huntsman (Neosparassus) is larger still, brown and hairy. The tropical or brown huntsman (Heteropoda) is also large and hairy, with mottled brown, white and black markings. The eyesight of these spiders is not nearly as good as that of the Salticidae (jumping spiders). Nevertheless, their vision is quite sufficient to detect approaching humans or other large animals from some distance.
Venom and aggression
Like most spiders, apart from the Uloboridae and some Liphistiidae and Holarchaeidae, Sparassidae use venom to immobilise prey. They have been known to inflict defensive bites, but are not widely regarded as dangerous to healthy humans. Huntsman spiders are widely considered beneficial because they feed on insect pests such as cockroaches and crickets.
There have been reports of members of various genera such as Palystes, Neosparassus (formerly called Olios) and several others, inflicting bites. The effects vary, including local swelling and pain, sometimes with nausea, headache, vomiting, irregular pulse rate, and heart palpitations, indicating some systemic neurological effects, especially when the bites were severe or repeated. However, the formal study of spider bites is fraught with complications, including unpredictable infections, dry bites, shock, and nocebo effects. An investigation into spider bites in Australia, in which Sparassidae figured prominently, did not note any severe or unusual symptoms resulting from confirmed bites from some of the most notorious genera, particularly Neosparassus.
It is not always clear what provokes Sparassidae to bite people, but it is known that female members of this family will aggressively defend their egg sacs and young against perceived threats. The rarity of bites on various body parts suggests that most are accidental or incidental, resulting from inadvertent handling. Bites from Sparassids usually do not require hospital treatment. In particular, no cases of necrosis have been reported.
Sound production in mating rituals
Males of Heteropoda venatoria, one of the huntsman spiders that seems to easily find its way around the world, have recently been found to deliberately make a substrate-borne sound when they detect a chemical (pheromone) left by a nearby female of their species. The males anchor themselves firmly to the surface onto which they have crawled and then use their legs to transmit vibrations from their bodies to the surface. Most of the sound emitted is produced by strong vibrations of the abdomen. The characteristic frequency of vibration and the pattern of bursts of sound identify them to females of their species, who will approach if they are interested in mating.
Images for kids
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Isopeda villosa (lower) extricating itself from its old exoskeleton (upper).
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A female Heteropoda venatoria consuming a katydid
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Australian sparassid egg sac hatching
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Palystes castaneus egg purse
See also
In Spanish: Sparassidae para niños
