Life expectancy is 25 to 30 years. Females grow slightly larger than males and display more variation in weight. Adult females range between seven and eight feet while adult males measure approximately seven feet at maturity. Newborn pups are 30 to 40 inches in length.
Newborn pups display a jet-black coat.
Mature females may also bear scars from aggressive males encountered during mating. During successive annual molts, the epidermis peels off with the old hair to reveal the bright new pelage underneath. This epidermal molt is like the snake's shedding of skin. The only other seal known to molt like this is the elephant seal. Mediterranean monk seals are found in the Aegean Sea, along the Mediterranean coast of Morocco, along the Algerian coast of Tunisia and in the eastern Mediterranean Sea.