The “Big Nosed” Seal

Hooded seals, Crystophora cristata, are named for their large elastic sac that extends from their noses to their foreheads expanding into a large balloon-like structure on adult males. Hooded seals have a black face and grey-blue coat of patterns with dark patches. Males are larger than females measuring an average 8-10 feet, weighing nearly a ton. Hooded seals are known to dive 1,000m for more than 50 minutes. The lifespan of a hooded seal is 30-35 years of age.

Description and Behavior

Hooded seals are known to be very aggressive compared to other seal species. Adult males display their aggression by inflating their “hood”(balloon-like structure on their face), growing twice the size of a football. The “hood”is an enlargement of the nasal cavity which develops at the age of 4 years. The hood forms a balloon on the head when inflated; when deflated, the hood hangs in front of the upper lip. Males also have an inflatable nasal membrane expanding like a red balloon from one nostril that sounds when shaken. The hood and membrane are used for demonstrations of aggression when threatened and as a signal during breeding season.

Nasal Cavity

The hooded seal is known primarily for its unique nasal cavity. Only males possess this
display-worthy accessory, developed around the age of 4. The hood begins to inflate as the

yooniqimages_101994918
seals take an initial breath prior to going underwater. It repeatedly inflates and deflates as the seal is swimming. the purpose of this “hood” is for acoustic signaling when it feels threatened, attempting to ward off hostile species when competing for resources. It also communicates their health and status of superiority to both males and the females they are trying to attract. A pink colored balloon-like nasal membrane comes out of the left nostril to further aid in attracting a mate. This membrane when shaken produces various sounds dependent of whether on land or underwater. 12% of the signals are used for sexual purposes.

 

Breeding and Life Cycle

The Gulf of St. Lawrence, the “Front” east of Newfoundland, Davis Strait and Jan Mayen are the four major breeding areas for the hooded seal. Within a single mating season, males have multiple mates, following the hypothesis that they are polygynous. Some are mobile and tend to mate with multiple females in short amounts of time, generating maximum offspring within the population, while others tend to and defend just one female for longer periods of time.

Within all areas, the hooded seal whelps, or birth, in March and early April and molt from June to August. It is estimated that 90% of the total Northwest population give birth on the “Front”; the Northeast around Jan Mayen, generally dispersing into the sea after breeding in March. From April through June, this species travels long distances to feed then eventually gather again. Some return to the same area in July to undergo molting, the majority go much further North. After molting, the species disperses widely again to feed in late summer and fall before returning to the breeding areas in the late winter.

Range and Habitat

Hooded seals are found in the deep waters in the far north of the Atlantic Ocean.
According to Marinebio, the total population is currently estimated to be 650,000. This
highly migratory

hooded_seal_range
Hooded Seal Range Map

species are known to wander long distances as far as west Alaska and as far south as the Canary Islands and Caribbean island of Guadeloupe. After breeding season, usually April to June, the hooded seals travel long distanced to feed. In June through August they reconvene on the ice to molt after which they separate to feed until breeding season in the late winter.

Feeding Behavior

Hooded seals feed in deep waters, diving to depths ranging from 100 to 600 m. Their diet differs territorially and includes: halibut, redfish, cod, wolfish, capelin, and herring. Octopus, squid, sea stars, shrimp and mussels are also eaten.

Polar bears, Greenland sharks and orcas are known predators of hooded seals.

Conservation

Brought about by international cooperation and the formation of the Northwest Atlantic Fisheries Organization (NAFO), conservation practices led the hooded seal population to increase. It is required to hold a license to hunt them in international waters and each license is set a quota.

The Hooded Seal is protected under the Marine Mammal Protection Act of 1972.

Resources:

“Hooded Seals, Cystophora Cristata.” MarineBio.org. MarineBio, 14 Jan. 2013. Web. 24 Nov. 2016.

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