Harp seals boast a wide range of pelages through their development. Harp seal pups are born with a white coat of embryonic fur or lanugo, which gives them the name “whitecoats.” Some pups’ fur may be dyed yellow at birth by amniotic fluid, but it fades to white after a few days. About 21 to 22 days later, pups begin to lose their white fur in tufts, creating a “jagged coat.” The lanugo is replaced by a silver-white coat with irregular black spots, which the juvenile seal or “beater” retains for a year. After 12 to 14 months the blacks spots grow larger and the seal is called a “bedlamer.” The seal remains a bedlamer until it reaches sexual maturity. When the seal reaches sexual maturity (around 5.5 years old), the blacks spots converge into a “harp” shaped design, which is composed of two black lines that run up the dorsal side of the seal’s flanks, starting at their pelvis and curving and converging between the shoulders. Also, adult harp seals develop a black head and may have black markings where the hind flippers meet the body of the seal. Some harp seals retain their spotted pelage (“spotted harps”). Of the seals that retain their spots, some have dark gray streaks, creating a completely gray pelage (“sooty harps”). The harp-shaped design on the backs of adults, along with the black head and sliver-white fur, helps Pagophilus groenlandicus stand out from the other members of Phocidae that share its habitat.
Harp seals are sexually dimorphic in size and pelage. Male harp seals weigh an average of 135 kg and are 171 to 190 cm long. Females weigh an average of 120 kg and are 168 to 183 cm long. Besides being larger than females, male harp seals tend to have a more-defined “harp” pattern and black head than females.
Adult harp seals have fairly small hind flippers and the fore flippers are pointed with short digit tips that boast large claws. Their heads are flat and wide and they tend to have a fairly long, but tapered snout.
The dental formula of Pagophilus groenlandicus is 3/2 incisors, 1/1 canines, and 5/5 post-canines.
Range mass: 120 to 135 kg.
Average mass: 130 kg.
Range length: 1.5 to 2.0 m.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry ; polymorphic
Sexual Dimorphism: male larger; male more colorful