|Researched by||Ruby Nash||Refereed by||This information is not refereed|
|Other common names||-||Synonyms||Cystophora borealis Nilsson, 1820|
The hooded seal is a relatively large seal, famous for its balloon-like nasal appendage. It has a small head, reaches up to 2.5 m in length and weighs up to 400 kg. Males are typically longer and heavier than females. Its flippers are short compared to the size of the body and are dark in colour. The face is completely black. The young are generally blue all over with silver bellies. After maturity, it develops a silver to greyish body colour with irregular dark spots over most of the body. Males have a distinct nasal appendage that hangs as a sac over the nose. When inflated this sac covers the front of the face and top of the head. The sac is dark in colour. Males can also inflate an elastic balloon-like bladder from one nostril. The bladder appears red and can cover part of the face.
Cystophora cristata is probably an occasional visitor (vagrant) to the waters of Britain and Ireland.
Recorded in the Arctic Ocean and the high latitudes of the North Atlantic. The majority of hooded seals (Cystophora cristata) are recorded off the east coast of Canada, Davis Strait, West Ice and the east of Greenland. It has also been sighted in the Strait of Gibraltar and off the Spanish coasts of the Mediterranean Sea.
The hooded seal is a marine neritic and oceanic species. It is associated with sea ice and exhibits seasonal migration with females and males keeping separate except when meeting to breed in the spring.
Cystophora cristata are very efficient divers. They can dive to 1000 m for at least an hour. Diving depth and duration depend greatly on the season and are generally longer in the winter. This is thought to be associated with prey behaviour and the vertical distribution of fish and zooplankton (Folkow & Blix, 1999). Cystophora cristata stores oxygen in their blood and skeletal muscles during dives, which helps prevent diving hypoxia. Low oxygen levels can cause traumatic injuries or even death if they are prolonged. They also undergo cardiovascular alterations such as the constriction of capillaries to ensure oxygen is reaching the most vital organs e.g. the heart and the brain. The brain of Cystophora cristata has cerebral neurones, located in the uppermost part of the brain, that have a high tolerance to hypoxia and are able to fire effective signals during long dives (Folkow et al., 2008).
Kovacs, K.M. 2016. Cystophora cristata. The IUCN Red List of Threatened Species 2016: e.T6204A45225150. https://dx.doi.org/10.2305/IUCN.UK.2016-1.RLTS.T6204A45225150.en. Downloaded on 09 February 2021.
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Last Updated: 01/01/1970