Octopedal

Octopedal is an adjective describing organisms that walk on eight feet or eight leg-like appendages. The term is built from the Latin octo- meaning eight and ped- meaning foot, with the suffix -al indicating a characteristic. In scholarly writing, octopedal is used to denote locomotion or limb arrangement rather than to designate a taxonomic grouping.

Most commonly, octopedal refers to arachnids such as spiders (order Araneae) and harvestmen (order Opiliones), which habitually use four pairs of legs for walking. Many extinct arthropods with eight walking legs are described as octopedal in paleontological literature. The term conveys the functional property of eight leggedness rather than a specific taxonomic classification.

Cephalopods such as octopuses possess eight limbs, but these are not walking legs in the same sense as arthropod limbs; locomotion in octopuses is often achieved by jet propulsion, with limbs used for manipulation and limited crawling. Because of this difference in limb function, octopedal is less commonly applied to such animals in contemporary biology.

Octopedal contrasts with other limb-based locomotion terms such as bipedal (two feet), quadrupedal (four feet), and hexapodal (six feet). It is infrequently used outside discussions of limb counts and locomotor strategies.