Ectrodactylism in the harbour seal, Phoca vitulina L. (Mammalia:Phocidae)

Ectrodactylism in the hind limbs of a pinniped is described and discussed. This malformation is characterized by defective development of the distal phalanges which result in shortened, thick digits terminating in bulbous swellings. It is unlikely that such flippers are damaged as a result of some physical force; rather, the malformation appears to be of a congenital origin. To the authors' knowledge, this is the first report of a congenital limb deformity in a marine mammal.