Portia Labiata - Movement

Movement

When not hunting for prey or a mate, Portia species adopt a special posture, called the "cryptic rest posture", pulling their legs in close to the body and their palps back beside the chelicerae ("jaws"), which obscures the outlines of these appendages. When walking, all Portia species have a slow, "choppy" gait that preserves their concealment: pausing often and at irregular intervals; waving their legs continuously and their palps jerkily up and down; and moving each appendage out of time with the others and continuously varying the speed and timing. Portia′s walk is unlike that of any other spider, and this gait and the spider's fringes gives the appearance of light flickering through the forest canopy and reflecting from piece of detritus.

In most species of spider, an individual lays a continuous dragline of non-sticky silk as the spider moves, and from time anchors the dragline to a surface with a spot of sticky silk. This allows the spider to return to the surface if the spider is dislodged. A spider about to jump first lays a sticky silk anchor, and then pays out a dragline as it flies.

When disturbed, most Portias leap upwards about 100 to 150 millimetres, often from the cryptic rest pose, and often over a wide trajectory. Usually Portia then either freezes or runs about 100 millimetres and then freezes.

When isolated on little islands, Portias can enter the water by slowly placing their forelegs in the surface of the water, pushing off with the back legs, and adopting a spreadeagle position. A Portia then swims by moving one leg forward at a time.