The Spider of the Month (SOTM) is this juvenile ogre-faced net-casting spider (Asianopis sp.; Deinopidae). The photo was taken by me (Rudi Steenkamp), but the spider was found by Ruan Booysen on his fieldwork with Dr Mike Vickers in Ndumo Game Reserve in northern KwaZulu-Natal.
I was not aware that all the African Deinopis species were moved to Asianopis (Chamberland et al., 2022) so the SOTM on the Spider Club’s Facebook page ran with the name “Deinopis sp.”. The genus Deinopis and family Deinopidae both mean “fearful appearance”, from the Greek deinos (fearful) and opis (appearance). It can also mean “fierce-eyed”, depending on whether you consider “opis” to be feminine or masculine. There are three genera in the Deinopidae family, and two of them can be found in South Africa. There are 33 recorded Asianopis species in the world, with four recorded species in South Africa.
The Deinopis and Asianopis species have the largest simple eyes of any arthropod, and they use these posterior median eyes to hunt at night. These eyes are 2000 times more sensitive to light than human eyes. In fact, they’re so sensitive that the thin light-sensitive membrane in the eyes gets destroyed each morning when the sun rises, which they regrow again at night.
These spiders spin a small net, which they hold between their front legs, and then hang upside down, waiting for prey to pass below. They will sometimes drop some fecal matter on the ground as a reference point. When prey passes below, the spider catches it in its net. They have also been observed to catch flying insects in flight.