Like many spider species, Drassyllus depressus has no official common name. It is a member of the stealthy ground spider group (Family Gnaphosidae). There are many species in this family, but they are rarely seen. This is both because they are primarily nocturnal, but also because they are shy, and seek shelter out of view if they detect a nearby predator. They undoubtedly consider us humans, potential predators. These photos of Drassyllus were taken in captivity because it is so difficult to find and photograph them out in their habitat. Judging from the results of pitfall trapping, they are probably common, but mostly unseen, residents of our prairie.
In this photo the unusual posterior median eyes are highlighted with an orange arrow. They are highly reflective, sometimes appearing bluish. These eyes are adapted to sense the polarization of light, and since light from the sky is polarized, it may give them a clue that is helpful for navigation. The green arrow highlights the long tubular spinnerets (silk spinning organs) typical of the stealthy ground spider group. These spinnerets are used to spin a dense silk retreat where the spider spends the daytime sleeping. They are also used to produce a band of silk that can assist in the capture of prey.
Males of Drassyllus are often much darker in color than the females.
