chel(i)-

A claw.

Greek khēlē, claw.

A chela (plural chelae) is a pincer-like claw, especially of a crab or other crustacean; a chelicera (plural chelicerae) (Greek keras, horn) is either of a pair of appendages in front of the mouth in arachnids and some other arthropods, usually modified as pincer-like claws; the Chelicerata are a large group of arthropods (arachnids, sea spiders, and horseshoe crabs), all of which possess a pair of chelicerae. In chemistry, a chelate is a compound in which a central metal atom is bound to an organic molecule in two or more places, so named because the metal is figuratively gripped like a claw; a chelating agent uses a chelate to treat heavy metal poisoning.