Family: Scytodidae (spitting spiders)

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

The only genus of this family, Scytodes, can be regarded as the stealth fighter of spiders and is commonly called the spitting spider and is harmless to humans. Previously Scytodes was included in the same family as Loxosceles (violin spider, Sicariidae) and Drymusa (False Violin spider, Drymusidae). Scytodes is harmless, unlike Loxosceles which is venomous to humans).

Scytodes sp. [image N. Larsen ] Scytodes with egg sac. [image N. Larsen ]

Locally, this spider has abandoned a sedentary web life, unlike those in tropical regions, and instead roams nocturnally and actively hunts its prey. It can be found under bark, leaf-litter and sometimes in the home. There are 28 species known from South Africa and this genus has a worldwide distribution. Three cosmopolitan species can be found to inhabit dark recesses in homes.

Scytodes is derived from the greek "skytos" meanig "leather-like".

It is a small spider, about 5-9mm in length. It is shiny and glabrous (hairless) but with a scattering of short setae over the body and the base colour is mid-brown with darker symmetrical patterning of stripes and spots The thin legs are banded. It has a distinctive shape with a domed, oversized prosoma (a diagnostic feature of Scytodes) which houses an anterior venom gland that is connected to a posterior section that synthesises a sticky silk used for defence and prey capture. 

Scytodes is a nocturnal wanderer with poor vision and roams around with front legs raised to detect prey using long trichobothria (sensory hairs) on the metatarsi (second last apical segment of the foot). Once prey such as fish moths, moths, flies etc. is detected, it proceeds with such stealth that it goes unnoticed by its prey. Once within a range of up to 5-10mm, it ejects 2 streams of very sticky synthesized silk over its prey, gluing it to the substrate. In this rapid event (lasting about 140 milliseconds) the silk is ejected a distance of 15-20mm through the rapid contractions of large prosomal muscles. It appears that the victim is paralysed by a venomous component in the silk. The spider then advances and bites a leg of the prey and once dead, it is removed from its bonds dragged off to a safe retreat to be sucked dry leaving the empty remains. Prey capture has been well documented and two rows of horizontal zig-zag oscillations of silk have been described. However, in the Cape Town area, vertical oscillation has been observed with Scytodes testudo. It is not known if different methods are used randomly by all species or if the methods are species specific.

Unlike most spiders, Scytodes is quite long lived, being known to live from 2 to 4 years. After laying, the eggs are held together with a few strands of silk and carried around by the female in her chelicerae (fangs) although Bristow states that it is attached to the spinnerets and held with the palps leaving the chelicerae free for prey capture. Some species use a lace-like covering for the eggs. Eggs hatch about 2 weeks after laying and emerge 2 weeks later.

Text by Norman Larsen


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