Hooded seal

The hooded seal (Cystophora cristata) is a large phocid found only in the central and western North Atlantic, ranging from Svalbard in the east to the Gulf of St. Lawrence in the west. The seals are typically silver-grey in colour, with black spots that vary in size covering most of the body. Hooded seal pups are known as "blue-backs" because their coats are blue-grey on the back with whitish bellies, though this coat is shed after 14 months of age when the pups molt.

Naming

The generic name Cystophora means "bladder-bearer" in Greek, from the species' unusual sexual ornament – a peculiar inflatable bladder on the head of the adult male. This bladder hangs between the eyes and down over the upper lip in the deflated state. In addition, the hooded seal can inflate a large balloon-like sac from one of its nostrils. This is done by shutting one nostril valve and inflating a membrane, which then protrudes from the other nostril.

Size

Adult males are 2.6 metres (8 ft 6 in) long on average, and weigh 300–410 kg (660–900 lb). Sexual dimorphism is obvious from birth and females are much smaller: 2.03 metres (6 ft 8 in) long and weighing 145–300 kg (320–661 lb). The colour is silvery; the body is scattered with dark, irregular marks. The head is darker than the rest of the body, and without marks.