A chela ()also called a claw, nipper, or pinceris a pincer-shaped organ at the end of certain limbs of some

arthropod Arthropods ( ) are invertebrates in the phylum Arthropoda. They possess an arthropod exoskeleton, exoskeleton with a cuticle made of chitin, often Mineralization (biology), mineralised with calcium carbonate, a body with differentiated (Metam ...

s. The name comes from

Ancient Greek Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...

, through

Neo-Latin Neo-LatinSidwell, Keith ''Classical Latin-Medieval Latin-Neo Latin'' in ; others, throughout. (also known as New Latin and Modern Latin) is the style of written Latin used in original literary, scholarly, and scientific works, first in Italy d ...

'. The plural form is chelae. Legs bearing a chela are called chelipeds. Another name is ''claw'' because most chelae are curved and have a sharp point like a

claw A claw is a curved, pointed appendage found at the end of a toe or finger in most amniotes (mammals, reptiles, birds). Some invertebrates such as beetles and spiders have somewhat similar fine, hooked structures at the end of the leg or Arthro ...

Chelae can be present at the tips of arthropod legs as well as their

pedipalps Pedipalps (commonly shortened to palps or palpi) are the secondary pair of forward appendages among Chelicerata, chelicerates – a group of arthropods including spiders, scorpions, horseshoe crabs, and sea spiders. The pedipalps are lateral to ...

. Chelae are distinct from spider

chelicerae The chelicerae () are the arthropod mouthparts, mouthparts of the subphylum Chelicerata, an arthropod group that includes arachnids, horseshoe crabs, and sea spiders. Commonly referred to as "jaws", chelicerae may be shaped as either articulated ...

in that they do not contain venomous glands and cannot distribute venom.

Uses

Chelae have a wide variety of uses, but most commonly they are used for handling their prey and for defense. These uses are often reflected in the morphology of the chelae. For instance, some species, such as the members of the families

Ocypodidae The Ocypodidae is a family of semiterrestrial crabs that includes ghost crabs and fiddler crabs. These crabs are found along tropical and temperate shorelines worldwide. Some genera previously classified within the Ocypodidae family have been r ...

and

Alpheidae Alpheidae (also known as the snapping shrimp, pistol shrimp or alpheid shrimp) is a family (biology), family within the shrimp infraorder Caridea characterized by having asymmetrical claws, the larger of which is typically capable of producing a ...

show asymmetry between their paired claws. Possessing one enlarged chela used for defensive and courtship purposes and a smaller chela for shearing and feeding. For some species, this asymmetry between chelae may be a

sexually dimorphic Sexual dimorphism is the condition where sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, di ...

trait. whereas in others, like many species of

scorpions Scorpions are predatory arachnids of the Order (biology), order Scorpiones. They have eight legs and are easily recognized by a pair of Chela (organ), grasping pincers and a narrow, segmented tail, often carried in a characteristic forward cur ...

, it is not. An example of specialization of these asymmetrical chelae can be seen in the '' Alpheus heterochaelis,'' the bigclaw snapping shrimp. The enlarged snapping claws of these shrimp are capable of snapping shut with such force to shoot a jet of water and create a loud popping noise, which they use to deter predators and other members of their species. In scorpion species, the chelae are often used to grab hold of prey and then further subdue them by injecting them with the venom from their stingers, although some species rely solely on the chelae to subdue their prey. Scorpions also use their chelae for defense by using them to shield and protect their bodies. For scorpions, the chelae are formed at the end of the pedipalps and covered in sensory hairs that they use in a similar manner to insect antennae. Further uses of chelae include digging, burrowing, and climbing. Chelae also play an important role in many species mating rituals, such as to communicate and attract prospective mates, wherein species with asymmetrical chelae use their enlarged chela as a display to attract mates. Chelae are also used in the act of mating, where the male species will often use them to hold onto the female during the act.

References

Arthropod anatomy {{Arthropod-anatomy-stub

Uses

See also

References