Balaena mysticetus is the second largest whale in the world, second only to the blue whale (Balaenoptera musculus) . The name "bowhead" comes from their bow-shaped mouth. The lower jaw makes a U-shape around the upper jaw. This lower jaw is usually marked with white spots, contrasting with the rest of the whale's black body (Nowak 1999). Baleen in the bowhead whale's mouth is the largest of any cetacean with 300 baleen plates measuring 300-450 centimeters in vertical length. The skull makes up almost one-third of the total body length, is curved and asymetric (Lanier 1998). Bowhead whales, on average, are sixty feet in length and weigh around 100 tons. Contributing to the whale's mass is a two foot thick layer of insulating blubber (Nicklen 2000). Balaena mysticetus also has a small pectoral fin for its size, less than 200 centimeters in length (Nowak 1999). Bowhead whale females measure between 16 and 18 meters in length, males measure between 14 and 17 meters in length. Bowhead whales weigh from 75,000 to 100,000 kg.
Range mass: 75000 to 100000 kg.
Range length: 14 to 18 m.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: female larger