Sea Otter Trivia

According to the Otter Foundation, the California sea otter population declined from July 2008 to July 2011. Estimates suggest a California population of approximately 2,700 individuals.

Sea otters are considered a keystone species and play a major role in the community by controlling herbivorous invertebrates. Sea otters prey on sea urchins, thereby preventing sea urchins from overgrazing the kelp forest. This allows the kelp forest to thrive and contributes to an increase in marine diversity.

Sea otters are considered a keystone species and play a major role in the community by controlling herbivorous invertebrates. Sea otters prey on sea urchins, thereby preventing sea urchins from overgrazing the kelp forest. This allows the kelp forest to thrive and contributes to an increase in marine diversity.

Sea otters are considered a keystone species and play a major role in the community by controlling herbivorous invertebrates. Sea otters prey on sea urchins, thereby preventing sea urchins from overgrazing the kelp forest. This allows the kelp forest to thrive and contributes to an increase in marine diversity.

The distribution of giant kelp (Macrocystis pyrifera) forests limits the southern range to about 22 degrees North latitude.

Sea otters display sexual dimorphism as males are larger than females. Males measure 1.2 to 1.5 meters in length, while females measure 1 to 1.4 meters.

Sea otters are found in two geographic regions around Canada, the United States, and Mexico in North America and around Russia and Japan in Asia.

Sea otters are found in two geographic regions on the Pacific Coast around Canada, the United States, and Mexico in North America and around Russia and Japan in Asia.

Sea otters are capable of diving to depths of at least 45 meters.

Pups are weaned at around 6 months of age but start to eat solid foods shortly after birth.

Sea otters inhabit marine neritic and marine oceanic habitats. They can be found in temperate coastal waters with rocky or soft sediment ocean bottom and live in offshore forests of giant kelp (Macrocystis pyrifera).

Sea otters inhabit marine neritic and marine oceanic habitats. They can be found in temperate coastal waters with rocky or soft sediment ocean bottom and live in offshore forests of giant kelp (Macrocystis pyrifera).

Sea otters are polygynous, with males having multiple female partners throughout the year.

Sea otters communicate through body contact, scent, and vocalizations, although they are not overly vocal. Researchers have recognized nine vocalizations. Pups use squeals to communicate with their mothers. Other calls include coos, whines, distress screams, growls, snarls, and whistles.

When resting or sleeping, sea otters float on their backs and wrap themselves in kelp to keep from drifting.

Sea otters are one of few mammals that exhibit tool use.

Three regional subspecies of the sea otter have been confirmed and are recognized with distinct geographical distributions.

Sea otters are social creatures and congregate in groups when resting.

Sea otters utilize vertical undulations of the body to swim, tucking in the forelimbs and using the hind limbs and tail to control their motion.

Sea otters can reproduce year round, though there are peaks of birth in May to June in the Aleutian Islands and in January to March in California.

Sea otter fur is the densest of all mammals, with about 100,000 hairs per square centimeter.

Many males actively defend their territories. Disputes are usually settled with splashing and vocal displays, and fighting is rare.

Many males actively defend their territories. Disputes are usually settled with splashing and vocal displays, and fighting is rare.

Sea otter individuals tend to be specialized in their choice of prey. One otter may consume only urchins and crabs while another may eat mostly fish, depending on the abilities of the individual and local food availability.

The Asian sea otter is the largest subspecies and has a slightly wider skull and shorter nasal bones than both other subspecies. Northern sea otters are slightly larger than Californian otters. Adult male northern sea otters weigh 27 to 39 kilograms, while females weigh 16 to 27 kilograms. Adult male southern sea otters average 29 kilograms in mass, while females average 20 kilograms. Northern sea otters possess longer mandibles (lower jaws) while southern sea otters have longer rostrums and smaller teeth.

Sea otters are carnivorous. They will eat nearly any fish or marine invertebrate they can find in their kelp forest foraging grounds. Their diet consists of marine invertebrate herbivores and filter feeders such as sea urchins (Strongylocentrotus purpuratus and Strongylocentrotus franciscanus), sea stars (Pisaster ochraceus), limpets (Diodora aspera), coast mussels (Mytilus edulis), chitons (Katharina tunicata), and purple-hinged rock scallops (Crassadoma gigantea). Otters also eat crabs, octopus, squid, and fish.

Male sea otters have larger home ranges than females. The home range of a male may overlap with that of several females.

Sea otter fur was coveted due to its extreme density and insulating quality.

Sea otter fur was coveted due to its extreme density and insulating quality.

As of 2020, the sea otter is considered Endangered by the International Union for Conservation of Nature and Natural Resources (IUCN) Red List of Threatened Species.

Sea otters are long-lived. The maximum estimated lifespan of sea otters is 23 years in the wild.

Male sea otters do not provide any care for their offspring, but females do.

Sea otters are diurnal with crepuscular peaks in foraging activity.

Parasites and infectious disease contribute to sea otter mortality, specifically Toxoplasma gondii, which infects domestic cats (Felis catus), and Sarcosystis neurona, which infects opossums. These apicomplexan protozoan parasites infect the sea otter and cause encephalitis. It is postulated that cat and opossum feces travel to storm drains via runoff and disposal in toilets, eventually coming into contact with sea otters.

Parasites and infectious disease contribute to sea otter mortality, specifically Toxoplasma gondii, which infects domestic cats (Felis catus), and Sarcosystis neurona, which infects opossums. These apicomplexan protozoan parasites infect the sea otter and cause encephalitis. It is postulated that cat and opossum feces travel to storm drains via runoff and disposal in toilets, eventually coming into contact with sea otters.

Only one pup can be raised successfully.

Sea otters have circular, furry faces with short noses, rounded eyes and ears, and long whiskers that assist in foraging for food. Sea otters use their sensitive whiskers to locate small creatures in the dense kelp beds and crevices.

Great white sharks (Carcharodon carcharias) are one of the primary predators of sea otters. Otters are occasionally eaten by coyotes (Canis lantrans) after taking refuge on the sand during stormy weather. Young pups left alone on the surface while their mothers feed beneath the surface are preyed upon by bald eagles (Haliaeetus leucocephalus). It was once thought that killer whales (Orcinus orca) were responsible for declines in the sea otter population in Alaska, but evidence is inconclusive.

Great white sharks (Carcharodon carcharias) are one of the primary predators of sea otters. Otters are occasionally eaten by coyotes (Canis lantrans) after taking refuge on the sand during stormy weather. Young pups left alone on the surface while their mothers feed beneath the surface are preyed upon by bald eagles (Haliaeetus leucocephalus). It was once thought that killer whales (Orcinus orca) were responsible for declines in the sea otter population in Alaska, but evidence is inconclusive.

Great white sharks (Carcharodon carcharias) are one of the primary predators of sea otters. Otters are occasionally eaten by coyotes (Canis lantrans) after taking refuge on the sand during stormy weather. Young pups left alone on the surface while their mothers feed beneath the surface are preyed upon by bald eagles (Haliaeetus leucocephalus). It was once thought that killer whales (Orcinus orca) were responsible for declines in the sea otter population in Alaska, but evidence is inconclusive.

Great white sharks (Carcharodon carcharias) are one of the primary predators of sea otters. Otters are occasionally eaten by coyotes (Canis lantrans) after taking refuge on the sand during stormy weather. Young pups left alone on the surface while their mothers feed beneath the surface are preyed upon by bald eagles (Haliaeetus leucocephalus). It was once thought that killer whales (Orcinus orca) were responsible for declines in the sea otter population in Alaska, but evidence is inconclusive.

Sea otters prefer coastal waters up to 30 meters deep. The shallower the water, the less time is spent diving to reach food.

The tail comprises less than a third of the body length, measuring 25 to 35 centimeters, or 10-14 inches.

Sea otters are found in two geographic regions on the Pacific Coast.

Pups start diving at 2 months of age.

Sea otter milk is 20 to 25% fat.

Female sea otters have two mammae.

Sea otter couples engages in playful and sometimes aggressive behavior. The male holds the female’s head or nose with his jaws during copulation. Visible scars are often present on females from this behavior.

Scent is important in recognition and surveying physiological states. Each sea otter has its own distinct scent that conveys identity, age, and sex.

Scent is important in recognition and surveying physiological states. Each sea otter has its own distinct scent that conveys identity, age, and sex.

Scent is important in recognition and surveying physiological states. Each sea otter has its own distinct scent that conveys identity, age, and sex.

Sea otters keep the same rock for many dives.

Sea otters break open prey items with hard shells or exoskeletons with a rock. Some otters hold the rock on their chest and drive the prey into the rocks. Others leave the prey on their chests and hit the prey with the rocks.

The Asian sea otter is the largest subspecies.

Sea otters congregate in groups known as bevies, families, lodges, rafts, romps, or pods, when resting. Romp is descriptive of their playful nature, while raft is descriptive of their water-floating habits. Sea otters commonly feed in small groups.

Sea otters congregate in groups known as bevies, families, lodges, rafts, romps, or pods, when resting. Romp is descriptive of their playful nature, while raft is descriptive of their water-floating habits. Sea otters commonly feed in small groups.

Sea otters congregate in groups known as bevies, families, lodges, rafts, romps, or pods, when resting. Romp is descriptive of their playful nature, while raft is descriptive of their water-floating habits. Sea otters commonly feed in small groups.

Sea otters can swim as fast as 9 kilometers per hour, or 6 miles per hour, underwater.

A single pup is born weighing 1.4 to 2.3 kilograms.

The fur consists of two layers: a dark undercoat and longer, lighter-colored guard hairs, which trap a layer of air next to the skin to keep it dry.

Females reach sexual maturity at 4 years of age. Males reach sexual maturity at 5 to 6 years, but may not mate until much later.

Sea otters consume 20 to 25% of their body weight each day and usually eat 3 to 4 times a day.

Enhydra lutris nereis, the southern sea otter, is the smallest sea otter subspecies.

Sea otters are the only carnivores with just four lower incisors.

An otter’s den is called a holt or couch.

An otter’s den is called a holt or couch.

Sea otters were hunted to near extinction (1,000 to 2,000 individuals worldwide) at until the turn of the 20th century when the United States, Russia, Japan, and Great Britain reached an agreement in 1911 called the International Fur Seal Treaty, banning the hunting of fur-bearing sea mammals. In 1972, the U.S. Marine Mammal Protection Act offered further protection by banning capture and harassment of sea mammals.

Sea otters are vulnerable to large-scale population declines, with oil spills being the greatest anthropogenic threat. The Exxon Valdez oil spill of 1989 had a dramatic effect on the Alaskan sea otter population, killing approximately 5,000 individuals.

Sea otters have patches of loose skin under the forearms that they use to help store tools, such as rocks, so they can free up their paws while eating. They also use these loose folds of skin to collect and transport invertebrates during diving.

The pup typically remains dependent on the mother for about 6 to 8 months after birth.

Foraging dives usually last 50 to 90 seconds, but otters can remain submerged for nearly 6 minutes.

In September 2006, Governor Arnold Schwarzenegger passed a law raising the maximum fine for harming a sea otter to $25,000, and required that all cat litter sold in California display a warning label that advises not to dump cat feces down storm drains or in toilets.

The sea otter’s hind legs are long and the paws are broad, flat and webbed. The forelimbs are short and have retractable claws, which help with grooming and eating. Sea otters use their small, agile forepaws to capture the prey and rub, roll, twist, and pull the prey apart.

Twins occur in 2% of sea otter births.

Sea otters spend the majority of their time in the ocean, but rest on land when the population density is high or during stormy weather.

Sea otters spend the majority of their time in the ocean, but rest on land when the population density is high or during stormy weather.

Sea otters are one of several species of mammals that undergo delayed implantation in which the embryo does not implant during the immediate period following fertilization, but remains in a state of suspended growth allowing for birth to occur under favorable conditions.

Because males steal food from females if they get a chance, females tend to avoid males except when mating and forage in separate areas.

Sea ice limits the sea otter’s northern range to below 57 degrees North latitude.