One of the largest beaked whale species, Arnoux's beaked whale is almost identical in appearance to its close relative, Baird's beaked whale (Berardius bairdii
), but is smaller in size (2). The body is uniform blackish-brown or dark grey, with irregular white blotches on the underparts of some individuals (2), and may be extensively scarred with single or paired rake marks made by the teeth of conspecifics (2) (4). The melon is relatively small, with a steep, almost vertical forehead, beneath which a short, tapering snout projects (2) (5). Interestingly, the lower jaw projects well beyond the upper jaw, so that the lower, front pair of large teeth is constantly exposed (2).