Size and shape

White-beaked dolphins are robust animals with a stout body shape.  Adults reach around 3 m in length, with calves born just over 1 m in size.  The dorsal fin is tall, prominent and falcate and usually has a rounded tip.  The beak is short and thick, and is white or pale grey in colouration.

Colouration

This species has a very variable colour pattern, showing a large amount of variation between individuals, age groups and geographically.  The body is a mosaic of white, pale grey and dark grey/black pigmentation.  The throat and beak are white, and the eye is surrounded by a white patch.  The dorsal surface is mostly dark grey forward of the fin, but a white 'saddle' extends across the dorsal surface astern of the fin and back towards the tail.  The belly is white, and a thick white blaze extends from the shoulder, along the flank and back towards the tail.  The flippers and tail fluke are dark grey, and there is a dark grey/black 'teardrop' on the lower forward flank, narrowing towards the rear.

The dorsal fin is tall and falcate, and there is a white 'saddle' patch across the back behind the fin

The colour pattern is complex, but features a white beak, white flank blaze and white 'saddle' patch

Other clues

In the North Sea and on the Scottish continental shelf, groups of three to five animals are common.  In this area large groups of dolphins exceeding 20 animals are less likely to be white-beaked dolphins and may be one of the other species described below.  Dolphins observed in deep water off Scotland are unlikely to be white-beaked dolphins, since this species usually inhabits waters of less than 200 m depth.

Similar species

In Scottish waters a number of other cetacean species occur in shelf waters and some of these may be confused with the white-beaked dolphin.  The most likely species to be confused with white-beaks is the Atlantic white-sided dolphin (Lagenorhynchus acutus) which is superficially similar in body shape and has a white patch on its flank.  However, the white-sided dolphin is a smaller and more slender animal, with a sharply pointed dorsal fin and a conspicuous yellow-patch on the rear flank.  It also lacks the white beak and white saddle of the white-beaked dolphin, tends to occur in larger groups, and rarely bow-rides.  The short-beaked common dolphin (Delphinus delphis) also overlaps in distribution with the white-beaked dolphin, but should be readily distinguishable by its prominent longer beak and hourglass flank pattern with a diagnostic yellow-tan thoracic patch.  Bottlenose dolphins are larger and a uniform grey in colour with white undersides.  Given reasonable views the white-beaked dolphin should not be confused with any other Scottish cetacean species.