The form and function of retractile claws in the Felidae and other representative carnivorans

Recent behavioral studies have shown the primary organ of prehension used in capturing prey to be the claw equipped forelimbs. In light of its functional importance, the claw retractile mechanism for 15 felid species is described and its function studied . The anatomy of the claw retractile mechanism for felids is then compared to that of other carnivorans. For felids,claw retraction is mechanically possible due to the unique shape of the middle and distal phalanges. Claw retraction, however, is a function of the dorsal elastic ligaments and not of the forearm extensor muscles. The resistance provided by these ligaments allows for flexion of the wrist and digital joints without claw protrusion. Moreover, co-contraction of both forearm flexor and extensor muscles is necessary to produce claw protrusion. The functional anatomy of claw retraction for felids differs considerably from that of most other carnivorans. However, the claw retractile mechanism for some advanced viverrids is structurally similar to that of the felids. For these viverrids prey seizing, as in the felids, has become a function of the forelimbs. For the other families of carnivorans, the jaws and not the forelimbs are used as the primary organ of prehension and the anatomy of the claw retractile mechanism reflects functional demands placed on it other than grasping and holding prey.