Editing Claw (section)

===Mammals===
[[File:Katzenkralle.jpg|right|thumb|A claw sheath from a cat]]
All [[carnivora]]ns have claws, which vary considerably in length and shape. Claws grow out of the third [[Phalanx bones|phalange]]s of the paws and are made of [[keratin]]. Many [[predator]]y 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]]).<ref>{{Cite book |last=Turner |first=Alan |title=The Big Cats and their fossil relatives: an illustrated guide to their evolution and natural history |last2=Antón |first2=Mauricio |publisher=[[Columbia University Press]] |year=1997 |isbn=978-0-231-10228-5 |location=[[New York City]] |pages=130-133 |language=en}}</ref> A claw that is retractable is protected from wear and tear.

Most cats and dogs also have a [[dewclaw]] on the inside of the front paws. It is much less functional than the other claws but does help the cats to grasp prey. Because the dew claw does not touch the ground, it receives less wear and tends to be sharper and longer.

A [[nail (anatomy)|nail]] is [[Homology (biology)|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 [[Artiodactyla|artiodactyl]] [[ungulate]]s may also be called a claw). 

Every so often, the growth of claws stops and restarts, as does [[hair]]. In a hair, this results in the hair falling out and being replaced by a new one. In claws, this results in an [[abscission]] layer, and the old segment breaks off. This process takes several months for [[human]] thumbnails. [[Cat]]s are often seen working old unguis layers off on wood or on boards made for the purpose. Ungulates' hooves wear or self-trim by ground contact. Domesticated [[Equus (genus)|equids]] ([[horse]]s, [[donkey]]s and [[mule]]s) usually need regular trimming by a [[farrier]], as a consequence of reduced activity on hard ground.

====Primates====
[[Primate]] nails consist of the unguis alone, as the subunguis has disappeared. With the evolution of grasping hands and feet, claws are no longer necessary for locomotion, and instead most digits exhibit [[nail (anatomy)|nail]]s. However, claw-like nails are found in small-bodied [[callitrichids]] on all digits except the [[hallux]] or big toe. A laterally flattened [[grooming claw]], used for grooming, can be found on the second toe in living [[Strepsirrhini|strepsirrhines]], and the second and third in [[tarsiers]]. [[Aye-aye]]s have functional claws on all other digits except the hallux, including a grooming claw on the second toe.<ref name="Soligo">{{Cite journal | last1 = Soligo | first1 = C. | last2 = Müller | first2 = A. E. | doi = 10.1006/jhev.1998.0263 | title = Nails and claws in primate evolution | journal = Journal of Human Evolution | volume = 36 | issue = 1 | pages = 97–114 | year = 1999 | pmid =  9924135}}</ref> Less commonly known, a grooming claw is also found on the second pedal digit of [[night monkey]]s (''Aotus''), [[titi]]s (''Callicebus''), and possibly other [[New World monkey]]s.<ref name=Maiolino>{{Cite journal | last1 = Maiolino | first1 = S. | last2 = Boyer | first2 = D. M. | last3 = Rosenberger | first3 = A. | doi = 10.1002/ar.21498 | title = Morphological Correlates of the Grooming Claw in Distal Phalanges of Platyrrhines and Other Primates: A Preliminary Study | journal = The Anatomical Record | volume = 294 | issue = 12 | pages = 1975–1990 | year = 2011 | pmid =  22042603| doi-access =  }}</ref>