There have been very few sightings of this whale due to its spending little time on the surface. Of the roughly 35 specimens studied, the following is specific to M. bowdoini: indiviuals weigh 2.6 tons at their maximum and at birth the average length is approximately 2 meters. Females grow to an average of 4.6 m., with males growing slightly longer to 4.8 m. The color of males ranges from dark grayish-blue to black, except for the "beak", the tip of the rostrum and lower jaw, which are white in color. Females have more of an off-white beak.

Andrew's whale females or young are distinguished from other Mesoplodon species by their heads, which have a small melon and as a result, slants down dramatically from the body. Also, females and young have short, thick beaks. The dorsal fin of this species is rather small for its body size. This fin is found in the middle of the back, and it is triangular and blunt tipped.

The teeth of males are helpful in identification. Males have two teeth located in the lower jaw within a set of sockets in the middle of the beak. Females also contain these teeth, but they are not visible since they do not erupt through to the surface.

Average mass: 2359 kg.

Range length: 2 to 4.7 m.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: male larger