Genus: Opistophthalmus (burrowing scorpions)

Life > Eukaryotes > Opisthokonta > Metazoa (animals) > Bilateria > Ecdysozoa > Panarthropoda > Tritocerebra > Arthropoda > Arachnomorpha > Cheliceriformes > Chelicerata > Euchelicerata > Arachnida > Scorpiones (scorpions) > Superfamily: Scorpionoidea > Family: Scorpionidae

This genus is aptly referred to as the burrowing scorpions as most species do in fact burrow. Some species are psammophilous with long macrosetae allowing them to negotiate soft sand into which they burrow. Other species are pelophilous utilizing the enlarged chelicerae or chelae for digging in hard soil. These burrows are often constructed with a shallow scrape under rock that leads into the burrow. The burrows vary from 10 mm to 1 metre deep and may run to a length of 1,5 metres. Generally burrows in soft sand are longer with shorter burrows in harder soils. Certain species are scrape dwellers and do not burrow as adults, unlike the young that do burrow. The males of these scrape dwellers have elongated chelae. Scrape dwellers and the few species occurring amongst rocks are dorsoventrally flattened, but not to the extent of Hadogenes.

Opistophthalmus scorpions are bulky and often with very broad and powerful chelae that holds the prey firmly, crushing it to death. If the prey is too large, it is stung and held until it dies. It then orientates the prey and eats it head first. Some species, and especially the males, that occur under stones, have more elongated chelae. These scorpions vary a great deal in colour ranging from yellow through brown to black usually with darker or lighter areas. The leg colour is generally lighter than the rest of the body. The integument of some scorpions is smooth and shiny while others are granulated and dull.

When threatened, Opistophthalmus adopts an aggressive stance, body raised up off the ground and curled upward with the sting held above the head ready to strike. The pedipalp chelae are held forward protecting the face. Opistophthalmus readily stridulates by rubbing its chelicerae together and assuming its aggressive stance and executes numerous strikes with its sting but as with most harmless snakes is all bluff and makes for interesting photography. When in the burrow the broad chelae are effectively used to block the entrance to protect itself against intruders.

Three Opisthophthalmus species (O. glabrifrons, O. wahlbergii and O. boehmi) are currently available in the pet trade and this may necessitate their protection in the future as wild populations decline.

Species indigenous to southern Africa

There are 59 described species in southern Africa with 17 new species in preparation for publication. Some of the species are featured below.

Opistophthalmus macer

Occurs from False Bay to Worcester then eastward to Port Elizabeth in the Western and Eastern Cape. Total length of these scorpions are 115mm including the caudal segment (tail).

Opistophthalmus capensis

Has a distribution extending from St. Helena Bay on the west coast to Mossel Bay on the south coast of the Western Cape.

Opistophthalmus adustus

This attractive psammophilous scorpion occurs in the sand dunes of the southern Namib where it constructs multi-directional borrows up to 750mm below the surface. 

Opistophthalmus pallipes

Reaches 130mm total length and occurs in the Northern Cape and Western Cape, along the west coast from Namaqualand to the Cedarberg and Piketberg in the south. This scorpion constructs shallow burrows in rocky habitats. The male can easily be seperated from the female with his slender pedipalps.

 

Text and images by Norman Larsen .


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