The body of these whales is around 6-7 meters in length. The head is small with a long, narrow beak. The dorsal fin is small and is located 1/3 of the body length from the tail. The tail fluke is not notched, and the flippers are small and oval in shape. The back is uniform grayish-brown in color, fading to nearly white on the underbelly. Since very few of these whales have been seen while alive and body colors quickly darken following death, the true coloration of Tasmacetus shepherdi is not known (Evans 1987, Tinker 1988).
Shepherd's beaked whale can be easily distinguished from other members of the family Ziphiidae by the presence of 17-29 conical teeth in both the upper and lower jaw. Males possess two additional teeth on the anterior most part of the lower jaw. These teeth, described as possessing "bulbous bases and conical crowns", are larger than the homodont cheek teeth, and are separated from the cheek teeth by a 4 cm diastema. One tooth sits on either side of the mandibular symphysis (Walker 1975, Evans 1987, Tinker 1988).
The blowhole is crescent in shape and is asymmetrically located on the left side of the top of the head. The eye sits directly below the blowhole. The first five vertebrae are fused and the first through seventh pairs of ribs possess two heads (Evans 1987, Tinker 1988).
Range mass: 5600 to 6500 kg.
Range length: 6 to 7 m.