Elephant seals
Elephant seals are the largest seals in the world, with the males of the northern species reaching lengths of 13 to 16 feet and weighing between 4,500 and 6,000 pounds, while southern males can grow up to 20 feet and weigh as much as 8,700 pounds. These animals exhibit a distinctive gray coloration, with adult males featuring a notable trunklike extension of their nasal canal, which plays a crucial role in their communication and social behavior. Known for their loud barks and snorts, elephant seals have developed specific vocalizations and dialects within isolated groups.
Reproduction occurs in designated breeding grounds, where dominant males compete fiercely for mating opportunities with large harems of females. After a gestation period, females give birth to pups that are suckled for three weeks before being left to fend for themselves. Elephant seals are highly migratory, capable of traveling up to 13,000 miles annually in search of food, primarily squid and bottom-dwelling fish. After a significant period at sea, they return to land to shed their skin and hair before embarking on long foraging trips, making them the most migratory marine mammals on Earth. Despite their recovery from near extinction due to hunting, concerns remain regarding the limited genetic diversity of the northern elephant seal population.
Elephant seals
Elephant Seal Facts
Classification:
- Kingdom: Animalia
- Subkingdom: Bilateria
- Phylum: Chordata
- Subphylum: Vertebrata
- Class: Mammalia
- Order: Carnivora
- Suborder: Caniformia
- Family: Phocidae
- Genus and species:Mirounga angustirostris (northern elephant seal),M. leonina (southern elephant seal)
- Geographical location: Northern species inhabit the Pacific coastline from Mexico as far north as Alaska, and the waters of the northeastern Pacific Ocean; southern species inhabit specific areas of the southwestern Atlantic Ocean, the Kerguelen Islands in the southern Indian Ocean, and Macquarie Island off the coast of New Zealand
- Habitat: Marine waters or coastal shores of temperate or subarctic seas
- Gestational period: About eleven months, which includes a delayed implantation of the fertilized ovum
- Life span: Twelve to twenty years; females generally live longer than males
- Special anatomy: Massive size; presence of large, trunklike extension of the nasal cavity in the males; hind flippers for swimming
Elephant seals are the largest seals on earth. Male northern elephant seals attain a mature length of thirteen to sixteen feet, and may weigh between 4,500 and 6,000 pounds. Males of the southern species are larger and heavier than their northern cousins, and may reach a length of twenty feet, and weigh as much as 8,700 pounds. Females of both species are smaller. Their weight varies according to certain conditions. Adult elephant seals are gray in color, which is more pronounced in the females. They have no fur, but have areas covered with short, firm hairs.
An adult male has a large, trunklike extension of the nasal canal. This organ plays a vital role in the behavior and communication of these animals. The trunk, which can be described as short, baglike, and fleshy, hangs downward and is longer in the northern species of elephant seals. The skull is large and serves as a point of attachment for powerful muscles that move the trunk. Adult males have huge canine teeth.
Reproduction, Behavior, and Communication
Elephant seals communicate by producing loud barks and snorts with their trunks and mouths. These noises are often highly specific within isolated groups. Several different dialects have been identified. Elephant seals reach sexual maturity rapidly. Females give birth and mate in specific breeding grounds. Males are competitive and battle with raised heads, facing each other. They use their canine teeth as weapons. Dominant males mate with a large harem of females that may number between forty and fifty. Pups are born on land and have a black fur coat at the time of birth. They are suckled for three weeks before they are abandoned. Females enter estrus and mate again immediately after weaning their last pup. Most mature females become pregnant every year.
Because of the value of their oil, both elephant seal species were hunted to near extinction. Successful reproduction and protection against hunting have enabled elephant seal populations to recover, but have left the northern elephant seal population with a limited gene pool. It is unknown how this lack of genetic diversity will affect the survival and future of this species.
Alternating between land and sea, a single elephant seal may travel up to thirteen thousand miles in one year. The migratory cycle starts toward the end of winter, after females give birth and conceive again. Females leave their breeding grounds and are soon followed by the males. Elephant seals search for food in specific foraging sites for about three months. Since they do not eat while on land, they dive continuously to great depths for their preferred diet of squid or bottom-dwelling fish. Once they haul themselves out of the sea onto land, it is time to shed. Shedding can take several weeks. When shedding is completed, the seals return to the ocean for up to eight months and search for food. Elephant seals are the most migratory marine mammals on earth.
Principal Terms
carnivore: an animal that eats flesh
estrus: a time during which females are receptive to mating
harem: a group of breeding females controlled by a single male
shedding: a process through which organisms lose and replace their external covering; in elephant seals this involves loss of hair and portions of worn-out skin
Bibliography
Le Boeuf, Burney J. Elephant Seals: Population Ecology, Behavior, and Physiology. Berkeley: U of California P, 1994. Print.
Nowak, Ronald M. Walker’s Mammals of the World. 6th ed. Baltimore: Johns Hopkins UP, 1999. Print.
Owings, Lisa. Elephant Seal. Minneapolis: Bellwether, 2014. Print.
Scott, Peter. The Encyclopedia of Mammals. 6th ed. London: Greenwich, 1999. Print.
Vaughn, Terry A., James M. Ryan, and Nicholas J. Czaplewski. Mammalogy. 6th ed. Burlington: Jones, 2015. Print.
Waller, Geoffrey. Sea Life: A Complete Guide to Marine Environment. Washington: Smithsonian Institute, 1996. Print.
Wilson, Don E., and Sue Ruff. The Smithsonian Book of North American Mammals. Washington: Smithsonian Institute, 1999. Print.