pulvilli

Pulvillus (plural pulvilli) is a term used in anatomy and entomology to describe small cushion- or pad-like projections on a body part, most commonly as adhesive pads on the distal segments of insect legs. In many insects, pulvilli are located on the pretarsi or distal tarsomeres and function to improve adhesion to smooth surfaces, complementing claws. The term emphasizes a pad-like structure rather than a hair-like seta.

Morphology and mechanism. Pulvilli are typically soft, highly flexible cuticular pads; their surfaces are often densely set with microscopic hairs or ridges and, in several groups, can secrete a wet adhesive or hold waxy secretions that aid adhesion. Some species rely on capillary forces, others on van der Waals interactions. The design and presence of pulvilli vary widely; in some taxa they are conspicuous, in others reduced to mere bristles or absent, with other structures like arolia fulfilling the adhesion function.

Taxonomic and ecological relevance. The structure and distribution of pulvilli can be diagnostic at higher taxa or inform about locomotion ecology, aiding movement on leaves, bark, or other surfaces. Researchers also distinguish pulvilli from other foot pads such as arolia or scopula. In botany and plant physiology, the term pulvillus is related to but distinct from the pulvinus, the leaf base motor organ.