Claws

Claws are hard, curved keratinous projections at the tips of many vertebrate digits. They function as tools for grasping, tearing, digging, climbing, and defense, and in some species are used for hunting. The term typically refers to the keratinous sheath that covers the distal phalanx; in humans, the analogous structures are nails, which are flatter and primarily protect the fingertips and assist in manipulation.

Anatomy and growth: In many mammals and birds, the claw consists of a hard outer plate called the unguis that grows from the nail bed, covering the underlying living tissue. Beneath the unguis is a softer subungual region in some species. Claws grow continuously, and growth rates vary with age, diet, and season. In many domesticated animals, regular trimming helps prevent overgrowth and discomfort.

Variations and examples: Some species have retractable claws (most cats) that can be withdrawn into a protective sheath, while others have non-retractable claws (dogs, bears). Birds of prey possess large, curved talons for seizing prey. Sloths and several climbing mammals have elongated claws that aid suspension and grasping. In reptiles and many small mammals, claws assist with digging and soil manipulation.

Maintenance and health: Claw integrity can be affected by overgrowth, injury, or fungal infections. Proper trimming, appropriate substrates for wear, and occasional veterinary care help maintain function and comfort. Improper trimming or damage can expose sensitive tissue and cause pain.

See also: In broader use, claw-like structures appear across animal groups under different terminology (pincers, talons, chelae), illustrating convergent evolution of grasping adaptations.