Sicarius (six-eyed crab spiders, six-eyed sand spiders)

Life > Eukaryotes > Opisthokonta > Metazoa (animals) > Bilateria > Ecdysozoa > Panarthropoda > Tritocerebra > Arthropoda > Arachnomorpha > Cheliceriformes > Chelicerata > Euchelicerata > Arachnida > Araneae > Araneomorpha > Family: Sicariidae

Sicarius sp. [image N. Larsen ]

Sicarius, like Loxosceles (also in the Sicariidae), has 6 eyes arranged in 3 diads that are widely spaced in a recurved row. The cuticle is leathery (coriaceous) with curved setae and is usually maroon or yellow in colour. It is a robust, flattened spider, 9 - 19 mm long and a legspan of about 50 mm. The legs are laterally placed, resembling a crab, hence the common name.

Sicarius is a living fossil that pre-dates the Gondwanaland drift some 100 million years ago and also occurs in South America. There are 6 species distributed in the Western Cape, Namibia and Northern Province. They occur in sand, on sand dunes, under rocks and rock overhangs and generally in the vicinity of antlion pits. Sicarius catches prey by hiding under the sand. It raises its body, digs a depession, drops into it and then covers itself with sand using the front legs. The prey is caught using the front legs when the prey runs over the concealed spider. If a Sicarius spider is uncovered it will be covered with fine sand particles that adhere to cuticle acting as an effective camouflage.

Silk is used only to make the cup-shaped egg sac that is constructed using a combination of sand and silk. The egg sac remains buried and spiderlings develop slowly. Adults can live as long as 15 years which is unusual as most aranaemorph spiders live for 1 to 3 years. Furthermore, a well nourished spider can live for a year without food or water.

Sicarius hahnii from the Northern Cape and Namibia is possibly the most lethal spider in the world. Fortunately, due to its habitat, it is rarely encountered and appears reluctant to bite. I have often scooped up a Sicarius by hand while looking for reptiles. This spider should not be handled, as there is no effective treatment.

Text and images by Norman Larsen


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