Ground Spider

a ground spider from Iten, Kenya. Photo © by Michael Plagens

Observed at Iten, Rift Valley, Kenya. Dec. 2015. Length, not including legs, about 8 mm.

A Sac Spider, near Clubionidae, Rift Valley, Kenya © Michael Plagens

By day ground spiders are normally hidden inside a silken retreat which they construct on or near the ground, for example under loose bark on a fallen tree branch. They emerge at night ranging over the soil and leaf litter in search of prey. I am reasonably sure this spider belongs to the Gnaphosidae or a closely related spider family. This individual was out of its retreat because of marauding driver ants, Dorylus. It has already lost three of its legs in its escape attempts. Many arachnids can jettison a leg when a predator grabs hold. At first there is a problem because spiders use pressure in their haemolymph (blood) instead of abductor muscles to flex the legs. Until the break is stopped by coagulation the pressure is lost and the spider cannot run! There are eight small eyes in two rows. Coloration is dark gray-brown with few markings.

Gnaphosidae -- a Ground-dwelling Sac Spider Family

More Information:

Kenya Natural History

Copyright Michael J. Plagens. Page created 16 Jan. 2016.