Born To Climb

Tarsus of stick insect showing euplantulae (arrows) and the tarsal claw

Stick insects live in trees and are adapted to climbing and “sticking” to vertical and horizontal surfaces. The tarsi of the legs are divided into 5 segments that maintain contact with surfaces. The first four segments are equipped with hairy pads called euplantulae. The terminal tarsal segment differs from the first four in the structure of the tarsal pad and the presence of a tarsal claw.

The tarsal claw is most useful for walking or climbing on rough surfaces. The claw is sharp like a spike and catches on ridges in the surface. The claw point slightly backward; its grip is directional. When the leg is pulled inward toward the body (as pulling the body forward) the claws provide a firm grip similar to an athlete’s cleats. When the leg is pushed away from the body to be extended forward, the claws easily release from the surface.