nonfooted

Nonfooted is an informal biological descriptor used to indicate that an organism lacks true feet or leg-like appendages. It is not a formal taxonomic category, but a descriptive label applied in zoology and paleontology to contrast with footed, or leg-bearing, organisms. The term derives from non- (Latin for “not”) and footed (having feet).

In practice, nonfooted organisms include many invertebrates and primitive or larval forms that move without walking on feet. Locomotion is achieved by means such as cilia or flagella, muscular contraction of a hydrostatic body, slithering, or swimming. Examples include some sponges and cnidarians like jellyfish, several worm-like groups such as nematodes, and many larval forms that lack developed limbs. Some organisms possess pseudo-appendages that are not true feet, such as pseudopodia, which are sometimes described as “false feet,” but are distinct from true feet.

The term is most useful as a coarse descriptive tool when discussing morphology, locomotion, or evolutionary history, rather than as a strict classification. It can intersect with debates about limb reduction, paedomorphosis, or secondary loss of limbs in certain lineages.