Northern Elephant Seal

Description:

The northern elephant seal (Mirounga angustirostris) is one of two species of elephant seal (the other is the southern elephant seal). It is a member of the family Phocidae ("true seals"). Elephant seals derive their name from their great size and from the male's large proboscis, which is used in making extraordinarily loud roaring noises, especially during the mating competition. There is a great sexual dimorphism in size. The males can grow to 14 ft (4 m) and 5,000 lb (2,300 kg), while the females grow to 11 ft (3 m) and 1,400 lb (640 kg). Correspondingly, there is a highly polygynous mating system, with a successful male able to impregnate up to 50 females in one season

Habitat:

Pt. Reyes National Seashore. The northern elephant seal lives in the Eastern Pacific Ocean. Feeding grounds extend from northern Baja California to northern Vancouver Island.[4] Males migrate as far north as Alaska and British Columbia,[4][5] while females migrate as far west as Hawaii.[4] They come ashore to breed, give birth and molt, mostly on offshore islands. While the pelagic range covers an enormous span, there are only about seven principal breeding areas, four of which are on islands off the coast of California. Recently increasing numbers have been observed in the Gulf of California. Breeding colonies exist at Channel Islands, Año Nuevo State Reserve, Piedras Blancas Light, Morro Bay State Park and the Farallon Islands in the US[6] and Isla Guadalupe, Isla Benito del Este and Isla Cedros in Mexico.[6] Some breeding has been observed at Castle Rock in Northern California and Shell Island off Oregon[7][8] and in January, 2009 the first elephant seal births were recorded in British Columbia at Race Rocks.[9] The California breeding population is now demographically isolated from the population in Baja California.[6]

Notes:

The northern elephant seals are nocturnal deep feeders famous for the long time intervals they remain underwater.[10] This species dives to great depths while feeding, typically between 300 m (1,000 ft) and 800 m (2,600 ft); moreover, the Northern elephant seal will generally not feed in depths of less than 200 m (700 ft).[5] Both sexes eat a variety of prey including pelagic, deep water squid, Pacific hake, sharks, rays, and ratfish.[5][10] Octopoteuthis deletron squid are the most common prey item, found in the stomachs of 58% of individuals sampled off the coast of California.[11] Elephant seals don't need to drink as they get their water from food and broken down fats. While hunting in the dark depths, it is partly thanks to the use of vision that the elephant seals seem to locate their prey; the bioluminescence of some prey animals can facilitate their capture. Elephant seals do not have a developed a system of echolocation in the manner of cetaceans, but it is assumed that their vibrissae, which are sensitive to vibrations, play a role in search of food. Males and females differ in both diving behavior. Males tend to hug the continental shelf while making deep dives and forage along the bottom,[4] while females have more jagged routes and forage in the open ocean.[4] Males return to the same feeding ground every year while female have less predictable feeding migrations. Elephant seals are preyed on by orcas and white sharks. Both are most likely to hunt pups and seldom hunt large bull elephant seals but have taken seals of all ages. The shark, when hunting adults, is most likely to ambush a seal with a damaging bite and wait to finish the kill until it is weakened by blood loss.[12]