limbless

Limbless is an adjective used in biology and medicine to describe organisms that lack limbs. In animals, limbless forms arise through evolution or developmental absence. The term covers snakes, legless lizards, amphisbaenians (worm lizards), caecilians, and many aquatic eels. Limb loss or reduction has occurred independently in many lineages, resulting in diverse morphologies while sharing a long, slender body plan.

Characteristics include elongation of the body and, in many cases, reduced forelimb and hindlimb girdles. Locomotion is varied: snakes employ lateral undulation, sidewinding, concertina, or rectilinear movement; legless lizards and caecilians use similar patterns or swimming. Sensory systems may differ: snakes often rely on pit organs and Jacobson's organ; some legless lizards have limited eyesight; caecilians use tactile and olfactory cues. Adaptations such as skull flexibility in snakes facilitate prey capture and can enhance burrowing. Habitat and lifestyle influence morphology, with aquatic species typically showing strong undulatory propulsion and streamlined bodies.

In humans, limblessness can refer to congenital limb deficiency or to acquired loss from injury or disease. Medical terms include amelia (complete absence of limbs) and meromelia (partial absence). Management emphasizes rehabilitation, mobility, and, where appropriate, prosthetic devices. While limblessness is a natural morphological trait in some animal lineages, in humans it is generally addressed within medical and rehabilitative frameworks to support function and quality of life.