Some beetles and beetle mites (Oribatida) have leg segments that are swollen in the middle or distally, giving the legs a bead-like appearance. Individual segments may be fusiform, bowling pin-shaped, oval, or subspherical.
A rare form of modification of the leg segments found in some beetles, mites, and ricinuleids has the appearance of mechanical ball and socket joints.
Some mites and insects have leg segments expanded into keel-like flanges or wing-like lateral extensions, either cuticular or composed of waxy cerotegument.
Jumping has evolved in many different lineages of arthropods. Perhaps the simplest kind of adaptation for jumping is greatly enlarged muscles on some basal segments of the hind legs. This type of adaptation for jumping is present in some mites (e.g., species of Eupodes) in the form of swollen femora of legs IV.
Author: David E. Walter
Content last updated Sept. 2006, unless indicated otherwise
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