Individuals of this species can reach up to 9.8m in length, but most are around 6.7-7.6m at the age of sexual maturity (7-14 years). They are sexually dimorphic, with males being up to 25% larger than females. The size of individuals in the Gully population (off Nova Scotia) is believed to be some 0.7m shorter than that of other Northern bottlenose whales. Individual whales may live up to 37 years (Herman 1980, MacDonald 1987, Whitehead et al. 1997a).

Northern bottlenose whales are varied in color, ranging from greenish-brown to chocolate and gray. Individuals may be blotted with patches of grayish-white and coloration is generally lighter on the flanks and underbelly, fading to a white or cream color. Young calves are generally chocolate colored in appearance (Evans 1987, Tinker 1988).

The body is long, robust and cylindrical and the beak is short, resembling a bottle in shape. Both sexes have large, protruding melons that are often vertical anteriorly in older animals and turn yellowish-white with age in males. The melon of the female is not as prominent as that of the male.The posteriorly-curved dorsal fin is 30-38cm in height and is located at a distance of 1/3 the total body length from the tail. The tail fluke lacks a medial notch and the flippers are small and pointed (Minasian et al. 1984, Tinker 1988).

The dentition of the species is highly reduced, with males possessing one or occasionally two pairs of short teeth in the tip of the lower jaw. These teeth never erupt in females, may never fully erupt in males, and often fall out with age (Minasian et al. 1984).

Range mass: 5800 to 7500 kg.

Range length: 9.8 (high) m.

Sexual Dimorphism: male larger