The harp seal (Pagophilus groenlandicus), also known as Saddleback Seal or Greenland Seal, is a species of earless seal, or true seal, native to the northernmost Atlantic Ocean and Arctic Ocean. Originally in the genus Phoca with a number of other species, it was reclassified into the monotypic genus Pagophilus in 1844. In Greek, its scientific name translates to "ice-lover from Greenland," and its taxonomic synonym, Phoca groenlandica translates to "Greenlandic seal."[2] This is the only species in the genus Pagophilus.
Harp seals spend relatively little time on land compared with time at sea. They are social animals and can be quite vocal in groups. Within their large colonies, smaller groups with their own hierarchies form.[2] Groups of several thousand form during pupping and mating season.[16] Harp seals can live over 30 years in the wild.[2] On the ice, pups call their mothers by "yelling," and "mumble" while playing with others. Adults "growl" and "warble" to warn off conspecifics and predators.[2] Underwater, adults have been recorded using more than 19 types of vocalization during courting and mating.[2]

Reproduction and development
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The harp seal is a fast ice breeder and is believed to have a promiscuous mating system.[17] Breeding occurs between mid-February and April.[16] Courtship peaks during mid-March and involves males performing underwater displays, using bubbles, vocalizations, and paw movements to court females.[18] Females, who remain on the ice, will resist copulation unless underwater.[18]

Females mature sexually between ages five to six.[2] Annually thereafter, they may bear one pup, usually in late February.[2] The gestation period lasts about 11.5 months, with a fetal development phase of 8 months.[18] There have been reported cases of twin births, but singletons are vastly more common.[19] The fertilized egg grows into an embryo which remains suspended in the womb for up to three months before implantation, to delay birth until sufficient pack ice is available.
Harp seal births are rapid, with recorded lengths as short as 15 seconds in duration.[18] In order to cope with the shock of a rapid change in environmental temperature and undeveloped blubber layers, the pup relies on solar heating, and behavioral responses such as shivering or seeking warmth in the shade or even water.[18]

Newborn pups weigh 11 kilograms (24 lb) on average and are 80–85 cm (31–33 in) long.[2] After birth, the mother feeds only her own pup. During the approximately 12-day long nursing period, the mother does not hunt, and loses up to 3 kilograms (6.6 lb) per day.[2] Harp seal milk initially contains 25% fat (this number increases to 40% by weaning as the mother fasts) and pups gain over 2.2 kilograms (4.9 lb) per day while nursing, quickly thickening their blubber layer.[18] During this time, the juvenile's "greycoat" grows in beneath the white neonatal coat, and the pup increases its weight to 36 kg (79 lb). Weaning is abrupt; the mother turns from nursing to promiscuous mating, leaving the pup behind on the ice. While courtship starts on the ice, mating usually takes place in the water.
After abandonment, in the post-weaning phase, the pup becomes sedentary to conserve body fat. Within a few days, it sheds its white coat, reaching the "beater" stage.[2] This name comes from the sound a beater's tail makes as the seal learns to swim.[19] Pups begin to feed at 4 weeks of age, but still draw on internal sources of energy, relying first on energy stored in the body core rather than blubber.[18] During this time the ice begins to melt leaving them vulnerable to polar bears and other predators. This fast can reduce their weight up to 50%. As many as 30% of pups die during their first year, due in part to their early immobility on land.

Around 13–14 months old, the pups molt again, becoming "bedlamers".[19] Juveniles molt several times, producing a "spotted harp", before the male adults' harp-marked pelt fully emerges after several years. In females, it does not emerge.

Seals congregate annually on the ice to molt, pup and breed before migrating to summer feeding grounds. Their lifespan can be over 30 years.

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