claw

A claw is a curved, pointed appendage found at the end of a toe or finger in most amniotes [羊膜动物] (mammals, reptiles, birds). Some invertebrates such as beetles and spiders have somewhat similar fine, hooked structures at the end of the leg or tarsus [跗骨] for gripping a surface as they walk. The pincers /pinsɚs/ [钳子] of crabs, lobsters and scorpions, more formally known as their chelae, are sometimes called claws.

A true claw is made of a hard protein called keratin. Claws are used to catch and hold prey in carnivorous mammals such as cats and dogs but may also be used for such purposes as digging, climbing trees, self-defense and grooming, in those and other species.

Similar appendages that are flat and do not come to a sharp point are called nails instead. Claw-like projections that do not form at the end of digits but spring from other parts of the foot are properly named spurs.

All carnivorans have claws, which vary considerably in length and shape. Claws grow out of the third phalanges of the paws and are made of keratin. Many predatory mammals have protractile claws that can partially hide inside the animal's paw, especially the cat family, Felidae, almost all of whose members have fully protractible claws. Outside of the cat family, retractable claws are found only in certain species of the Viverridae (and the extinct Nimravidae). A claw that is retractable is protected from wear and tear.

所有食肉动物都有爪子，爪子的长度和形状差别很大。Claw由paw的第三指骨长出来，由角蛋白组成。许多食肉哺乳动物有可伸长的爪子，可以部分隐藏在动物的爪子内，尤其是猫科动物，其几乎所有成员都有完全可伸长的爪子。在猫科之外，伸缩爪只在某些种类的蜥蜴科（以及已经灭绝的泥鳅科）中发现。可伸缩的棘爪可防止磨损。

A nail is homologous to a claw but is flatter and has a curved edge instead of a point. A nail that is big enough to bear weight is called a "hoof". (Nevertheless, one side of the cloven-hoof of artiodactyl ungulates may also be called a claw).

指甲与爪相似，但更平，有弯曲的边而不是尖。大到足以承受重量的指甲被称为“蹄”。（尽管如此，偶蹄类有蹄动物偶蹄的一侧也可称为爪）。

六级/考研单词: paw, curve, fingerprint, mammal, beetle, spider, grip, prey, dig, nail, digit, spur, tertiary, extinct, flatter, nonetheless