Hooded seal (Cystophora cristata)

Physical characteristics

Hooded seals are sexually dimorphic, with males generally larger and heavier than females. Their common name refers to a distinctive inflatable nasal structure on adult males: a flexible bladder or "hood" that can be extended over the head, and a separate inflatable sac that can be pushed out from a nostril to form a balloon-like display. The hood develops as males mature and is used in visual and acoustic displays during interactions with rivals and potential mates. The pelage is mottled grey and silver in adults; newborns have a different, often darker juvenile coat.

Life history and behaviour

Breeding and pup rearing are closely tied to ice conditions. Hooded seal pups are notable for an exceptionally short lactation period—among the briefest of any mammal—during which they nurse and put on a large proportion of their body fat before weaning in only a few days. Adults feed on a range of fish, squid and crustaceans, foraging at sea and making dives to capture prey. Natural predators include large marine carnivores such as polar bears and killer whales.

Conservation and human interactions

Hooded seal populations have been affected by historical hunting, changes in sea-ice habitat and other human activities. Some regional populations have declined, and the species' well-being is closely linked to the availability of stable ice habitat for pupping and moulting. Management measures, research and monitoring aim to balance subsistence and commercial uses with conservation needs as climate change alters their environment.

Notable facts and distinctions

• Taxonomy: Cystophora cristata is the species name; the genus name highlights the bladder-like nasal structure.
• Unique male anatomy: the "hood" and a single-nostril inflatable sac are used in displays and possibly sound production.
• Pup development: very rapid transfer of energy from mother to pup during a short lactation period.
• Longevity: individuals can live into their early thirties in the wild.

Because hooded seals depend on seasonal pack ice, continued monitoring of populations, careful harvest regulation and research into their ecology remain important for understanding how they will fare as ocean conditions change.