Otter Facts

Sea otters hold hands when they sleep.

Occasionally, sea otters sleep on the water by floating on their backs. To avoid floating away in the vast seas, they hold each other’s front paws as they sleep. Although they don’t always partake in this behavior, this is one of the most well-known and adorable otter facts out there.

Sea otters sleep together in groups, or “rafts”.

Like most mustelids, adult sea otters prefer to hunt alone. However, when it’s time for them to rest, they band together with other otters of the same sex. A group of otters can take many different names. Many refer to groups of otters as romps, bevies, or families. However, when they’re floating on water, the groups become “rafts”.

A single raft typically holds around 10 to 100 individual otters. Male otter rafts tend to be bigger than female rafts. The largest recorded otter raft even contained over 2,000 individual otters.

Otters are part of the weasel family.

All otters belong to the family Mustelidae, also known as the weasel family. This family includes weasels, honey badgers, skunks, and wolverines, among others. Mustelids are among the oldest carnivorous mammals to exist on Earth, first evolving around 40 million years ago. Most mustelids have long bodies, short legs, and thick fur – however, the sea otter is the largest of all mustelids.

They are adapted to hunt in the water.

Otters have webbed feet and are strong swimmers adapted to hunting in the water. These animals can maneuver with great agility in the water by using their muscular tails as rudders. When diving, otters can also close their ears and nostrils to prevent water from getting in. In terms of hunting, otters often ambush their prey, but they can also chase them for a sustained period of time.

Additionally, otters are quite agile and fast in the water. Giant river otters can reach a top swimming speed of 8.7 mph (14 km/h), which is almost twice as fast as the fastest human swimmer, Michael Phelps!

Otters can hold their breaths for a long time.

Given that otters hunt in the water, it is not surprising that they have special adaptations for aquatic life. That said, an inning against an otter in a breath-holding contest would be no easy feat, because sea otters can hold their breath for up to 5 minutes. River otters, on the other hand, can hold their breath for up to a whopping 8 minutes. The lung capacity of otters is around 2.5 times greater than any mammal of similar sizes.

They can smell underwater.

Otters have a good sense of smell, and one of the more interesting otter facts is that they actually are capable of smelling things underwater. This is quite a unique adaptation because smelling things underwater for most mammals can only result in inhaling water, which puts them at risk of drowning. Even large marine mammals like whales and seals don’t rely on their sense of smell underwater.

Surprisingly, some otters can smell their prey as they swim. They do so by exhaling air bubbles from their noses, capturing the smell inside the air bubbles, and quickly inhaling them again.

Otters can snuggle.

This is another one of those otter facts that are just too cute to miss. Smooth-coated otters often rub their bodies against one another, often in pairs or groups. This full-body contact, not unlike what we call snuggling, strengthens their social bonds and also refreshes their thick coats.

They use tools.

Relatively few animals can use tools to get by, but otters make the cut. Without particularly strong jaws, otters have to rely on tools to open the hard shells of mollusks and crabs. Among the more well-known otter facts is their use of rocks as hammers to crack open the shells of their prey.

Otters can store items under their arms.

In addition to their tool use, they also can keep their rocks for convenience. Otters have a loose patch of skin underneath their armpits that act as pockets for storage. This allows them to store food and even their prized rocks for safekeeping. Interestingly, some otters may even use the same rock throughout their whole lives.

Otters are playful.

Like humans, dolphins, crows, and dogs, otters also engage in play. Otters usually fool around for enjoyment and socialize with other otters. Many have observed otters making waterslides and also sliding on land. They also can wrestle with other otters and like to shuffle rocks, showcasing a behavior similar to juggling.

They groom their fur a lot.

Otters take hygiene very seriously. Their fur serves a lot of important functions and therefore requires a lot of maintenance. If their fur gets dirty, it can affect their ability to float and regulate their body heat. Therefore, it’s important for otters to regularly groom their fur. Otters have loose skin and quite flexible bodies and have the ability to reach and groom fur from every part of the body.

When grooming, otters untangle knots and ruffle their fur out to clean themselves, which often looks like scratching. Otter mothers can also blow fur into their pups’ fur to keep them warm and buoyant. Additionally, sea otters roll around in water frequently to wash food scraps off of their fur.

Baby otters can float but can’t swim.

As marine mammals, sea otters can spend their whole lives without touching dry land. They typically give birth in the water, usually producing a single baby otter or pup. Unlike other species, sea otter pups have dense fur, teeth, and developed eyes at birth.

Although pups can float, they don’t instinctively know how to swim and have to rely on their mothers for around six months up to a year. Mothers would carry their pups on their stomachs and teach them important survival skills such as swimming, hunting, and cracking open shells.

Otters have the densest fur of all mammals.

Like many other members of the weasel family, otters have a thick coat of fur. This fur isn’t just for show, either, because their thick fur provides another one of their unique adaptations to life in the water. Made of two layers, their fur repels water and traps air underneath it. This helps their bodies stay dry and warm beneath the coats. Furthermore, the air beneath the fur helps them stay buoyant.

Sea otters especially need this thick coat of fur because their range extends to the Arctic. Unlike other marine mammals like seals and whales, they don’t have blubber to protect them from the sheer cold. Instead, they have an exceptionally thick coat, even having the densest fur among all mammals. On average, otters have around 800,000 to 1,000,000 individual hairs per square inch.

Otter mothers wrap their babies in kelp to keep them from floating away.

Because sea otter pups can’t swim, they’re prone to floating away with the waves of the sea. For this reason, pups are entirely dependent on their mothers to keep them safe and well-fed. When mother sea otters dive for food, they leave the pups on the surface. To keep them from floating away, they wrap the pups in kelp. Adult otters may also wrap themselves in kelp to stay anchored when resting or feeding.

Cat poop can be deadly for an otter.

Otters face many threats, with most otter species being vulnerable or endangered. They face grave challenges such as poaching, habitat destruction, and water pollution. One of the more peculiar threats, however, is the typical housecat. Sometimes, cat poop may contain a certain strain of parasite called Toxoplasma gondii. When otters come across infected scat, either on land or in polluted waters, they can get sick and potentially die.

A rescue otter developed asthma and learned how to use inhalers.

Though it’s not uncommon for otters to use tools, you’d be surprised by their capacity. For one, a rescued sea otter at the Seattle Aquarium serves as a living example of how clever otters can get. Aside from being the first sea otter to be diagnosed with asthma, Mishka learned how to use an inhaler designed for cats. How’s that for amazing otter facts?

Otters can help humans in fishing.

For generations, humans have employed the help of otters to fish in rivers using a technique called “otter fishing”. The practice of otter fishing dates back to the 6th century and was a popular method of catching fish throughout many regions of the world. Marco Polo even observed this practice in the 13th century on Yangtze River.

For this method, otters would chase fish into nets, after which the humans would retrieve the nets. After a good catch, humans would reward otters with some fish to eat. To this day, the practice remains alive in southern Bangladesh.

Sea otters are important to the ecosystem.

If you’ve ever come across kelp forests teeming with life near the coast of California, you can thank sea otters for those. As a keystone species, sea otters play a huge impact on the ecosystem they live in.

The otters feed on sea urchins, which feed on the stems of kelp. If left unchecked, sea urchins could cause kelp plants to drift away and die off. The affected areas subsequently become urchin barrens and would have very little biodiversity. As such, sea otters help balance the kelp forests’ ecology by feeding on the urchins that would otherwise collapse it.

Another one of the most interesting otter facts is that they also help control climate change to an extent. Since kelp forests capture carbon dioxide from the atmosphere, the presence of otters helps supply oxygen to the world.

Giant otters are social animals.

While most otters prefer to hunt alone, giant river otters are social butterflies. These animals hunt in packs and live in groups of extended families. The average giant river otter group has four to eight members, but they can also range from 2 to 20 individual otters. These otter groups are usually tight-knit, staying together to hunt, sleep, and play. They also have social hierarchies with one dominant breeding pair in the family.

Otters can overpower alligators.

In the rivers of South America, giant otters sit at the top of the food chain. These apex predators feed on cichlids, catfish, and even piranhas. They aren’t picky eaters and will eat almost any species of animal they can manage to catch.

Because they tend to hunt in groups, giant otters can overpower animals that are much larger than them. This includes caiman, anacondas, and alligators. Even a single otter can take on an alligator using their stamina. Prolonged thrashing can cause lactic acid buildup in alligators, which eventually paralyzes and kills them. The giant otters then can use their sharp teeth and claws to feast on the alligators’ organs.

Otters can help raise their siblings.

Around 2% of sea otter births result in twins, which usually ends in a competition between the two pups, or the mother abandoning one of them. However, river otters don’t have such intense sibling rivalry. In fact, older otters can help their mothers raise their younger siblings by catching food for the pups.

Giant otters are the most vocal species of otters.

Because they are highly social animals, it’s no surprise that giant otters need to communicate with others. These otters communicate with each other through complex vocalizations. They can make 22 distinct vocalization types, each relaying its own message. Depending on their intentions, giant otters can bark, scream, growl, or whistle. Impressively, each giant otter family has its own unique sound signature.

Otters are voracious eaters.

Like weasels, otters have a high metabolic rate to keep their bodies warm in colder waters. Their metabolism varies from species to species and under different environmental temperatures. European otters typically consume around 15% of their body weight in food each day, while sea otters can eat up to 20–25% of their body weight in one day.

While otters eat a variety of foods, they heavily favor seafood. They mostly eat fish, but can also eat shellfish, frogs, crabs, birds, or even large reptiles. In one day, otters would hunt for three to five hours. However, otter mothers nursing their young need more food than usual, hunting for up to eight hours a day.

Sea otters are the heaviest mustelids.

Among the weasel family, sea otters are the heaviest members, surpassing wolverines. Sea otters grow to about 3.3 feet (1 m) long and reach a body weight of 55–99 pounds (25–45 kg). Although they are the largest mustelids by mass, they are the smallest marine mammals. Meanwhile, giant otters have longer bodies that can reach up to 5.6 feet (1.7 m) long. In comparison, they are significantly less massive than sea otters, only reaching a weight of up to 71 lbs (32 kg).

Sea otter mating rituals can sometimes be lethal.

Although sea otters look innocent and adorable, their mating habits can sometimes be devious and deadly. Male sea otters are aggressive in mating, and will often forcibly grasp female otters. They also bite down on the females’ noses, which typically leaves deep wounds and scars and the occasional tearing away of flesh.

Mating takes place in the water and lasts for around 10-30 minutes. During this time, the two otters thrash and spin violently. The male sea otters sometimes hold the females underwater until mating is done, resulting in the drowning and death of the females. As much as 11% of sea otter deaths are due to this aggressive mating behavior.

To add to these gruesome otter facts, the deaths aren’t restricted to female sea otters. Male sea otters sometimes attack baby harbor seals and attempt to copulate with them. They also engage in necrophilia, attempting to mate with the otters and baby seals that have been dead for up to a week. Others reported sea otters copulating with dead birds and even dogs.

Some otters mate for life.

While most otters are promiscuous, some pairs of river otters stay monogamous and may sometimes mate for life. Some remain monogamous only in the breeding season. That said, other species such as the North American river otters are strictly polygynous.

They have diverse cultural depictions.

For the religion of zoroastrianism, otters are near sacred creatures. They believe that otters belong to the deity Ahura Mazda, and killing otters is therefore taboo. The atonement for killing these “water-dogs” would be to kill ten thousand frogs, ten thousand snakes, ten thousand tortoises, and tens of thousands of other animals in its place.

In Japan, otters are quite the tricksters. Like foxes and tanuki, the Japanese believe that otters deceive humans in many ways. One popular belief is that otters shapeshift into children or beautiful women. They do this in order to lure men and kill them. There are also stories in China that note the otters’ shapeshifting powers.

Some Native American tribes view otters as totem animals, and they often associate the animals with good luck. Others may also view them as symbols of loyalty. For some tribes, however, otters are symbols of death and drowning.

Otters can kidnap pups for ransom.

When female sea otters dive for food and leave their pups on the surface, males sometimes take advantage of them. They kidnap the pups and hold them hostage for a price. In some cases, the male sea otter would hold the pup’s head underwater until the female brings him food.

Otters are hard to handle.

Otters may look adorable and cuddly, but they’re known to attack humans and other animals. Some people poach these animals to keep as pets, but quickly learn that they are hard to handle.

Most otters spend a lot of time on land.

Although sea otters live a mostly marine-based life and are awkward on land, other otter species spend most of their time on dry land. For these species, they would only dive into the water to hunt and travel. Moreover, they need to spend time on dry land to keep their dense fur from being waterlogged.