Elephant Seals By: Jen Cooley Megan Flox Northern

Overview  Species Traits  Breeding Behaviors  Sexual Dimorphism  Underwater Expertise  Foraging  Habitat  Ecosystem  Human Impact  Q & A  Sources

Species Traits The northern elephant seal is a large marine mammal. Adult males weigh 2-7 times more than adult females. Adult males measure up to 4.5 m long and weigh up to 2300 kg. Adult females measure up to 3.6 m long and with up to 750 kg. Males live up to 17 years and females to 22 years.

Species Traits Coat is dark gray to brown. They have an annual molt on the shore during the warmer months between March and July for about 2-3 weeks. It's called a “radical molt” because the fur comes off in sheets.

Species Traits Each sex and age class molts at a different time, beginning with immature seals early in the season and ending with bulls which molt in July. In the Autumn juvenile seals congregate at the colony sites for around 2 months beginning in late September and lasting until November.

Breeding Behaviors Polygamous (one male with multiple females). Females reach sexual maturity 3-5 years old and males 4-6 years. Males reach their productive peak at 9-12 years. Large adult males arrive at the breeding grounds in December to compete for access to females.

Breeding Behaviors Females usually give birth to the previous year’s pup in January. Pups are born 1.5 m long and 30 kg in weight. Pups are born with black hair which is replaced by a silvery coat after they are weaned about 3-4 weeks later.

Sexual Dimorphism Male Elephant SealFemale Elephant Seal When males reach puberty at about 7 years old, they develop a large inflatable nose, or "proboscis." Adult males inflate it during the winter breeding season to resonate sound when vocally threatening each other.

Underwater Expertise Elephant Seals are able to dive very deeply and for extremely long periods of time. Males can dive 350 to 800 meters. Females can dive 300 to 600 meters. Dives are average minutes longer for males followed by a brief 3 minute surface interval. They remain submerged 80-95% of the time spent at sea. Researchers have identified 5 different dive patterns, they associate with travel, sleep and foraging. They also have a habit of holding their breath for as long as 25 minutes.

Underwater Expertise

Foraging Elephant Seals are the only mammals with a biannual migratory pattern. Carnivorous (Kingdom Animalia, Phylum Chordata, Class Mammalia, Order Carnivora, Family Phocidae, Genus Mirounga). Females will travel from California and Baja all the way to Mexico to feed. Males will travel from California and Baja to the Gulf of Alaska to feed. Cephalopods are an important part of the elephant seal’s diet as well as rays, Pacific Whiting, sharks, skates and pelagic red crabs.

Habitat California has about 84,000 northern elephant seals. Mexico has about 32,000 northern elephant seals. Northern elephant seals spend much of the year, generally about 9 months, in the ocean. They congregate onshore during breeding season, molt season, and the juvenile “haulout” period in the autumn. Dark Blue: Breeding Colonies Light Blue: Non-Breeding Individuals

Ecosystem Predators of Northern Elephant Seals Great White Sharks Orcas Prey of Northern Elephant Seals Fishes and Skates Rays and Sharks Pelagic Red Crabs Cephalopods

Human Impact Elephant seals were nearly hunted to extinction for their blubber in the 19th century. Received protection under U.S. and Mexican law and the species recovered. Genetic diversity is low because recovered population came from only a few ancestors. Entanglement in gillnets still causes around 100 deaths per year. Entanglement in marine debris, fishery interactions, and boat collisions are their main threats.

Q & A Sources