The nightglider's erectile spines are formed from modified hairs that, in the course of evolution, have developed into stiff needlelike structures.
The nightglider, Hastatus volans, is a small, nocturnal, arboreal, gliding musteline mustelid from the tropical forests of South America.
During the day it hangs on trees disguised against the bark, floating down to feed upon nocturnal insects, frogs and smaller mammals at night. Its method of hunting is to impale its prey on the spines that project from its chest.
The nightglider parachutes silently down on to its quarry, impaling it on its chest spines.
There are several species of nightglider. Each is camouflaged against particular species of forest trees.