Otter

Otters are mammals that have adapted to a life close to the water. They are the only member of their family, Mustelidae, to spend extended periods in or under water. Other members of their family include weasels, wolverines, and badgers. Carnivorous by nature, their diets include fish and invertebrates.  

These creatures are often spotted grooming themselves as they must keep their fur clean to stay buoyant and remain insulated. This is why the global otter population is at risk, due to oil spills and other forms of pollution clogging their fur, making it hard to survive.

List of the Common Types of Otter Species

There are 13 known species of otter found globally.

Physical Description and Appearance

Size: Length: 2.0 to 5.9 ft (0.6 to 1.8 m)

Weight: 2.2 to 99.2 lb (1 to 45 kg)

The Asian small-clawed otter is the smallest at 16 to 24 inches (41 – 64 cm) and 4.4 to 11 lbs. (2 – 5 kg), and the giant otter is the longest at 3.3-5.6 ft (1-1.7m) while the sea otter is the heaviest at 31-99 lb (14-45 kg).

Body and Coloration: Otters are long and slim, with relatively short limbs. Their feet are webbed with sharp claws on them. Except for the sea otter, all otters have long, muscular tails for steering. They have two layers of fur. The underfur is soft and insulated, protected by an outer layer of long guard hairs.

Their body color comes in different shades of brown, be it light cinnamon or dark brown. The dorsal part mostly appears dark, while the ventral region is of a lighter shade.

Where are they found

They reside on every continent except for Australia and Antarctica.

Habitat

Otters are found in varied aquatic habitats, such as coastlines, freshwater rivers, lakes, marshes, and oceans.

How long do they live

The average lifespan of an otter is 10-16 years. In captivity, they may live up to 20 years.

What do they eat

As carnivorous aquatic mammals, both fresh and seawater species of otters thrive on fish and crabs. Sea and marine otters consume abalone, clams, mussels, snails, and urchins. Those living in freshwater habitats eat birds, crayfish, frogs, mollusks, and small mammals.

Behavior

• Depending on the species, otters can be social like the giant otter or territorial like the river otter. Social species play “games” that include chasing their tails, sliding into the water, and wrestling with other group members.
• Most otter species are nocturnal, except for the sea and giant otters, which remain active during the day. The clawless and river otters on the other hand are known to show both diurnal and nocturnal behavior.
• Otters spend long periods grooming themselves, cleaning their fur by biting and scratching. They also rub against grass and rocks to remove dirt from their bodies, as well as rub their faces with their hands to drive out moisture and spread out the natural oil secreted by them.
• Inquisitive by nature, these smart aquatic mammals will investigate any unknown entity in their surroundings.
• When asleep, otters are often observed holding hands. This is more common in those otters at rest at sea, where by cuddling they anchor themselves and prevent themselves from drifting away.
• They are active hunters, with some like the sea otter even using rocks to break the shells of abalones and clams.
• While underwater, otters will sometimes exhale out bubbles from their nostrils onto the surfaces of objects. After inhaling these bubbles again, they can effectively “smell” underwater.

Predators

Adults have few predators, however, the pups, old, and infirm ones may fall prey to wolves, birds of prey, and large reptiles. Sea otters found in Alaska are preyed upon by killer whales.

Adaptations

• The guard hairs in the outer layer of their fur protect the inner coat from becoming dirty. The inner layer, besides providing insulation, also traps air allowing the otter to float on water.
• Their feet have webbing between the paws, allowing them to swim with ease. Also, most otters except for the clawless otter have sharp claws for grabbing and holding prey.
• The tails of most otter species are powerful enough to propel them forward while swimming.
• Otters hold their breath for long periods underwater, closing their nostrils and ears to prevent water from coming in. This is possible due to their high lung capacity, which can be 2.5 times greater than similar land species.
• Several species live in cold waters and need a high metabolism to keep them warm. They maintain this metabolic rate by eating constantly. At 10 °C (50 °F), an otter needs to consume 3.5 oz of fish per hour to survive.
• They have keen senses, such as good hearing, smelling, and vision that help them when underwater. Otters also use their whiskers to detect movement in their surroundings.

How do they reproduce

During the mating season, males approach a female and attempt to embrace her with their forelegs or rub and sniff her body. If she reciprocates, the two engage in a period of play, which includes chasing, diving, and swimming. Copulation takes place in the water, lasting for 10 to 30 minutes.

In some species, the male bites the female’s upper jaw or nose, while in others, the male grabs her by the nape. The male sea otter, in particular, may leave behind scars on the female’s nose due to their violent form of mating.

Life Cycle

After a 2-5 months gestation period, female otters give birth to 1-5 young, though 2 is the average number of offspring. While most otters give birth in dens, sea otters do so in water.

The baby otters, called pups, have sealed eyes that only open after a month. After two months, they begin swimming.

At one year of age, the pups leave their mother. Females reach sexual maturity at 2 years, while males do so at 3.

Conservation

According to the IUCN’s Otter Specialist Group, most species are “Near Threatened” or “NT”, “Vulnerable” or “VU”, or “Endangered” or “EN”.  The only exception is the North American river otter, listed as “Least Concern” or “LC.

The threats faced by otters include loss of habitat, hunting for their pelts, and oil spills. Otters are currently protected by the Endangered Species Act, 1973 (ESA), the Marine Mammal Protection Act of 1972 (MMPA), and the International Fur Seal Treaty signed by Britain, Japan, Russia, and the U.S. in 1911.

Otters – FAQs

Interesting Facts

• Japanese folklore heavily features the otter. There are several stories about otters turning into beautiful women and then killing men. Other myths include turning into a bōzu (a monk) which grows larger or shapeshifting into a severed head when caught in fishing nets.
• Fishers in southern Bangladesh bred smooth-coated otters and used them to chase fish into their nets. This traditional use of domesticated wild animals is still in practice in the district of Narail, Bangladesh.
• Otters were often hunted for their pelts, which were used to create robes for royalty, hats and belts for men and mittens for children.
• On October 2021, the U.S. Postal Service issued a series of stamps featured the otter playing in the snow.
• Otters have often been symbolized as playful creatures, and often are representations of curiosity and mischievousness in several cultures.
• On December 10, 2021, in Singapore a man was attacked by a gang of 20 otters and was bitten 26 times in 10 seconds. He survived the attack and was administered tetanus shots.