Family: Theraphosidae (baboon spiders)

Life > Eukaryotes > Opisthokonta > Metazoa (animals) > Bilateria > Ecdysozoa > Panarthropoda > Tritocerebra > Arthropoda > Arachnomorpha > Cheliceriformes > Chelicerata > Euchelicerata > Arachnida > Araneae >  Mygalomorpha

African species are called baboon spiders due to their hairy appearance and the black scopulae pads on its "feet" resembling the pads on baboon feet. These spiders are often incorrectly referred to as tarantulas, a name usurped by the American species from the European wolf spider (family Lycosidae) Lycosa tarantula. 

This family belongs to the suborder Mygalomorpha. This is a primitive spider group that some scientists believe should belong to its own order as, for example, the scorpions. These harmless giants are often negatively portrayed as villainous monsters especially in movie industry. They are not dangerous to man although they can inflict a painful bite. They are all mildly venemous, the venom being neurotoxic. However, the smaller species from the Western Cape, Harpactirella lightfooti is reputed to be dangerous to man although there is no evidence of this.

In South Africa this family is represented by five genera including thirty-four described species. Ceratogyrus, the horned baboon spider, is distributed across the northern parts of South Africa and its bordering countries.

Harpactira the common baboon spider, occurs over the whole of South Africa and bordering countries.

Pterinochilus, the golden-brown baboon spider occurs from north-eastern South Africa northwards to Ethiopia.

There are two lesser baboon spiders, Brachionopus, which is rare and is restricted to the eastern parts of South Africa and Harpactirella that occurs in the southern parts of South Africa.

All South African species are terrestrial occurring in underground burrows or scrapes under rocks. The scrape is lined with thick silk, which is attached to the rock and keeps out troublesome insects such as ants. At night, the burrow dwellers can be seen with their front legs and eyes showing at the entrance of their burrows as they wait for unsuspecting prey.

Females usually stay close to their retreat while the males, once mature, roam freely looking for a mate. For this reason, most of the specimens brought to the Museum for identification are males.

Theraphosids are large, bulky and hairy with a body length of 13-90 mm long with the average spider measuring 20-50 mm. They have robust non-tapering legs and the pads or scopulae setae under the "feet" allow them to walk up the smoothest of surfaces - even glass.

Most theraphosids are difficult to identify due to the lack of distinctive external characters. However, Ceratogyrus is easy to identify by the distinctive horn or plug projecting from carapace. The shape of this projection is used to identify to species. Normally this projection is fixed but during a moult is rotates slowly and is used to loosen the old skin. Species without this projection have instead a groove (fovea) and they use other means for loosening the skin.

The most dramatic feature of these spiders is the black fangs that can exceed  6 mm in length and are parallel to each other (paraxial). The fangs are set into the jaws (chelicerae) that project forward (porrect). These spiders are black and hairy underneath (ventrally) except in the region of the fangs where the hair colour rnages from orange to a pink/red tinge. During an attack, the forelegs are raised in aggression, exposing the fangs and the orange and black colouration. Dorsally the colouration varies enormously ranging from black, various shades of brown and shades of copper and cinnamon. The abdomen can be plain or marked with spots or chevrons.

Harpactira atra threat display. [image N. Larsen ©]

The eight eyes are arranged on the carapace on a central tubercle set back slightly from the anterior (front) edge of the carapace. This is called the clypeus and if there is no clypeus, one can be assured that the spider is not a theraphosid but another family instead (either Barychelidae, Cyrtauchenidae or Nemesiidae). All mygalomorphs have two pairs of ventral booklungs that operate on the principle of infusion rather than the more efficient system of inhalation. These spiders are therefore not very active and tire easily.

In other spider families, the males are easily recognised by the expanded ends of the palps where the sperm-carrying organ, the embolus, is situated. The expanded palp ends are not that noticeable in male theraphosids but males can also be recognised by the less bulky abdomen and by a tibial spur situated ventrally on the distal aspect of the tibia of the first pair of legs. The spur is not obvious as it is concealed amongst long hairs (setae) and rather resembles a pointed brush. The spur is used to restrain the females' fangs during copulation.

The female lays 30 to 180 eggs but very few survive the 7 to 10 year maturity period. Unlike the true spiders, the araneomorphs, the mygalomorph females continue to moult after reaching maturity and can live for about 25 years. The males live for only about 6 months after maturity and therefore it is of no consequence should the females consume them.

Due to the slow maturity rate and high mortality of immatures, the collecting of baboon spiders is strongly discouraged, as this has led to the decimation of populations. They do not make ideal pets as they are inactive during the day and move around very little even at night. Once the novelty of scaring ones friends has worn off, most spiders in captivity eventually die of dehydration, stress from handling and sheer neglect.

As mentioned above, theraphosids are harmless to man although the bite is painful and mildly neurotoxic. If bitten, one will experience an intense burning pain in the region of the bite where two red blood spots will develop from the fang punctures. There will be no evidence of discolouration and swelling. Depending on the species, the pain will subside after 2-18 hours. There might be symptoms of shock. The only treatment required would be a painkiller and antihistamine. However, as mentioned earlier, Harpactirella lightfooti is thought to be harmful to man although there is no evidence of this.

Some American species defend themselves by creating a cloud of barbed (urticating) hairs by rubbing them off their abdomens often leaving two bald patches. These hairs irritate sensitive tissue in the nasal cavities and eyes of predators and are known to cause blindness. Thankfully, this is not a characteristic of the African species.

Text by Norman Larsen ©