Harbor Seals live near coastlines and eat a highly varied seafood diet, depending on what is available. They can dive as deep as 450 m and stay under for almost half an hour, but six-minute dives to depths of 30-100 m are more usual. Females usually have one pup a year, and two weeks after the pup is born, mate again. The fertilized egg stays dormant in the uterus for up to three months before it implants in the uterine wall and begins to grow. This is called delayed implantation. Total gestation, including the period of delay, lasts 8-9 months. Instead of being born with the white coat typical of most seals in the family Phocidae, the pups often molt before birth, shedding the very soft white or pale gray coat called a lanugo while they are still in the uterus. Like dogs, Harbor Seals can suffer from heartworm. The disease has been found in North American and European populations.

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Mammal Species of the World