The pup is born with a fine-textured woolly white coat or lanugo, which keeps the pup warm until it acquires an insulating layer of blubber. The lanugo is shed by the age of eight weeks. The adult's coat is made of stiff guard hairs and occurs in various colour patterns. The underside may be silvery white to creamy yellow with a scattering of black spots while the back is dark grey marked by grey-white rings. By counting annual growth rings in the dentine layers of their teeth, the oldest recorded age for a ringed seal is 43 years.
Sexual maturity occurs between the ages of five and ten.
After ten years of age the females have a high annual pregnancy rate. Breeding males have a strong, musky odour and may be territorial. The peak of mating activity is in April and the embryo development is delayed for 81 days followed with a 9-month gestation period. Little is known about diseases in seals. Some afflictions include skin diseases, pneumonia and numerous parasites.