Editing Harp seal (section)

===Reproduction and development===
[[File:Harp seal mother and pup.jpg|thumb|Nursing]]
The harp seal is a fast ice breeder and is believed to have a promiscuous [[mating system]].<ref>{{cite journal |last1=Miller |first1=Edward H. |last2=Burton |first2=Lauren E. |year=2001 |title=It's all relative: allometry and variation in the baculum (os penis) of the harp seal, ''Pagophilus groenlandicus'' (Carnivora: Phocidae) |journal=Biological Journal of the Linnean Society |volume=72 |issue=3 |pages=345–355 |doi=10.1111/j.1095-8312.2001.tb01322.x|doi-access=free }}</ref> Breeding occurs between mid-February and April.<ref name="Fisheries"/> While [[Courtship (animals)|courtship]] starts on the ice, mating usually takes place in the water.<ref name="NOAA"/> Courtship peaks during mid-March and involves males performing underwater [[Courtship display|display]]s, using bubbles, vocalizations, and paw movements to court females.<ref name="Ronald-1982">{{cite journal |last1=Ronald |first1=K. |first2=J. L. |last2=Dougan|s2cid=23015146 |title=The Ice Lover: Biology of the Harp Seal (''Phoca groenlandica'') |journal=Science |volume=215 |issue=4535 |year=1982 |pages=928–933 |jstor=1688319|doi=10.1126/science.215.4535.928 |pmid=17821351 |bibcode=1982Sci...215..928R }}</ref> Females, who remain on the ice, will resist [[copulation]] unless underwater.<ref name="Ronald-1982"/>

Females become [[sexually mature]] between ages five to six.<ref name="Perrin-2009" /> Annually thereafter, they may bear one pup, usually in late February.<ref name="Perrin-2009" /> The gestation period lasts about 11.5 months, with a [[fetal development]] phase of 8 months.<ref name="Ronald-1982"/> There have been reported cases of [[twin birth]]s, but singletons are vastly more common.<ref name="Britannica">{{Cite encyclopedia|url=https://www.britannica.com/animal/harp-seal|title=Harp seal {{!}} mammal|encyclopedia=Encyclopedia Britannica|access-date=2018-04-03|language=en}}</ref>{{Better source needed|date=March 2025|reason=Needs a research paper to supplement this claim ([[WP:NOTRS]]).}} The fertilized egg grows into an embryo which remains suspended in the womb for up to three months [[Delayed implantation|before implantation]], to delay birth until sufficient pack ice is available.<ref name="Perrin-2009" />

Harp seal [[birth]]s are rapid, with recorded lengths as short as 15 seconds in duration.<ref name="Ronald-1982"/> In order to cope with the [[Cold shock response|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.<ref name="Ronald-1982"/>
{{Multiple image
| image1            = Weaned harp seal pup.jpg
| direction         = vertical
| caption1          = A weaned harp seal pup
| image2            = Harp seal pointing upwards.jpg
| caption2          = Juvenile harp seal—a "bedlamer"
}}
Newborn pups weigh {{convert|11|kg|lbs}} on average and are {{convert|80|–|85|cm|in|abbr=on}} long.<ref name="Perrin-2009" /> 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 {{convert|3|kg|lb}} per day.<ref name="Perrin-2009" /> Harp seal milk initially contains 25% [[fat]] (this number increases to 40% by weaning as the mother fasts) and pups gain over {{convert|2.2|kg|lb}} per day while [[Lactation|nursing]], quickly thickening their [[Blubber|blubber layer]].<ref name="Ronald-1982"/> During this time, the juvenile's "greycoat" grows in beneath the white neonatal coat, and the pup increases its weight to {{convert|36|kg|lb|abbr=on}}. Weaning is abrupt; the mother swiftly turns from nursing to [[Promiscuity#Other animals|promiscuous]] mating, leaving the pup behind on the ice.<ref name="NOAA">{{Cite web |title=NOAA - Harp Seals | date=20 April 2022 |url=https://www.fisheries.noaa.gov/species/harp-seal#:~:text=Harp%20seal%20pups%20have%20long,more%20than%203%2C100%20miles%20roundtrip.}}</ref> In the post-weaning phase (after abandonment), the pup becomes [[Sedentary lifestyle|sedentary]] to conserve body fat. Within a few days, it [[Moulting|sheds]] its white coat, reaching the "beater" stage.<ref name="Perrin-2009" /> This name comes from the sound a beater's tail makes as the seal learns to swim.<ref name="Britannica" /> 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.<ref name="Ronald-1982"/> 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.<ref name="Perrin-2009" /> During this time the ice begins to melt, leaving them vulnerable to [[polar bear]]s and marine predators such as [[killer whale]]s and [[greenland shark]]s.<ref>{{cite web | url=https://oceana.org/marine-life/harp-seal/ | title=Harp Seal }}</ref><ref>{{cite web |title=Somniosus microcephalus (Bloch & Schneider, 1801) Greenland shark |url=https://www.fishbase.se/summary/Somniosus-microcephalus?ref=biodaily.it |website=fishbase.se |publisher=FishBase |access-date=20 March 2025}}</ref> 

Around 13–14 months old, the pups molt again, becoming "bedlamers".<ref name="Britannica" /> Juveniles molt several times, producing a "spotted harp", before the male adults' harp-marked pelt fully emerges after several years. In females, it may not emerge.<ref name="Perrin-2009" />

Seals congregate annually on the ice to [[molt]], pup and breed before migrating to summer feeding grounds. Their lifespan can be over 30 years.<ref name="Perrin-2009" />