10 Incredible Otter Facts

Written by Emmanuel Kingsley
Updated: January 29, 2024
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Otter is a term that can refer to a river otter, a sea otter, or a giant otter. An otter is a mammal with about 13 different species. Part of the Mustelidae family, otters have a presence on virtually every continent with their major habitats being lakes, river banks, as well as streams

Below are 10 other incredible facts about the otter, some of which may be new to you!

Infographic of 10 Otter Facts
Otters have voracious appetites and eat as much as 20-33% of their body weight daily.

1. Not All Otters Are Sea Otters

Otter

River otters, including the European otter, are smaller than sea otters.

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Often, people refer to otters as “sea otters.” While there are sea otters, not all otter species are sea otters in a strict sense. There are also river otters, who mostly live in freshwater and feature swift movement on land and in water. They also swim belly down while they paddle with their webbed feet. 

Sea otters, on the other hand, reside almost exclusively in the ocean along coastlines. Unlike river otters, they move haphazardly on land, and they paddle mostly with their hind feet. Sea otters are also much bigger than river otters.

2. Otters Can Be Described in Many Ways

river otter vs sea otter

A group of otters on land is called a “romp.”

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One fun, incredible otter fact is how you describe otters. When talking about or describing otters, there are quite a number of terms involved. For example, a group of otters has a range of names, including family, bevy, lodge, romp, or raft. “Romp” is commonly used for a group of otters on land, while “raft” is commonly used for a group of otters in the water. 

While male otters are called boars, female otters are called sows. Infant otters are commonly called pups, but they are seldom called kits and kittens. Quite a number of names, right? 

3. Otters Are Voracious Eaters

What Do River Otters Eat?

Otters can eat up to 33% of their body weight in a day.

©iStock.com/Troy Levengood

Otters have voracious appetites across all 13 species. Scientists say they eat food with daily amounts weighing as much as 20-33% of their entire body weight. Little wonder they often spend up to five hours each day seeking food. 

They will eat virtually anything they can catch, with their diets dependent on their habitats. For instance, the North American river otter primarily eats trout, salmon, crayfish, and suckers. Otters’ diets typically include fish, crayfish, crabs, frogs, and turtles, as well as snakes, birds, and their eggs.

Thanks to their healthy appetites, sea otters keep the sea urchin population at bay by eating them, thereby protecting kelp forests that have long suffered destruction from sea urchins. The consequence of that is an indirect reduction in the levels of atmospheric carbon dioxide. 

4. Sea Otters Have Favorite Rocks

Cutest Animals: Sea Otter

A fun otter fact is that otters usually store rocks used to crack open shellfish, in their underarm pouches.

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We mentioned earlier that sea otters spend up to five hours foraging daily because of their appetite. They often take rocks along with them. They put these rocks in their body pouches and use them to crack open captured shellfish. Scientists say they all have a favorite rock that they go with for these very important expeditions, and they usually store them in the pouches under their left arm.

5. Sea Otters Sometimes Hold Hands While Sleeping

Otters hold hands to keep from floating away from one another.

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Some sea otters hold hands while sleeping or resting. They lie on their backs, floating on water while holding hands.

Besides the cuteness of it all, otters hold hands to keep from floating away from one another. In fact, when it comes to a mother and her pup, the mom will sometimes hold the pup on her belly to keep it from floating away from her. 

6. Sea Otters Have Incredibly Dense Fur

otter

Sea otters have 1 million hair follicles per square inch, making their fur 1,000 times thicker and denser than human hair. 

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The honor for the thickest fur of all animals belongs to the sea otter. Now, isn’t that an interesting otter fact?

Experts say they have up to 1 million hair follicles per square inch, making their fur a thousand times thicker and denser than human hair. 

“Why do they need that much fur?” you might ask. Since they are the only aquatic mammals without blubber layers, all of that extra fur helps them with insulation as well as trapping much-needed air to help keep their bodies buoyant. This is not just natural air but also the air they are fond of blowing onto their pelts during grooming.

7. Only Female Sea Otters Look After Pups

river otter and pup

Mother sea otters spend up to 14 hours per day looking for food for their pups.

©iStock.com/Dgwildlife

In the world of sea otters, mothers often do all the work for their infant pups. Since they cannot swim until at least a month after birth, the mothers often have to blow air into their coats to make them buoyant enough for water. This activity is grooming, as referenced earlier. 

Mothers also reportedly spend as much as 14 hours every day just looking for food for their pups. They do all of this on their own without any assistance from their fathers. However, male Asian small-clawed otters look after the young. They will also bring food for both mother and baby.

8. Otters Are Swift Swimmers

otter swimming in clear water

An otter can hold their breath for up to 4 minutes.

©Jonathan Chancasana/Shutterstock.com

Otters have incredible swimming capabilities, with some reaching up to 7 miles per hour. To put that in perspective, that’s about three times faster than you if you are an average swimmer. Researchers say they can hold their breath for up to 4 minutes and deliberately close their nostrils to keep out water. 

9. Male Sea Otters Can Be Aggressive

The sea otter Enhydra lutris resting on seaside rock. It is a marine mammal native to the coasts of the North Pacific Ocean. The heaviest in weasel family

Despite their cute appearance, male sea otters can be aggressive.

©2009fotofriends/Shutterstock.com

Sea otters are often considered some of the cutest sea creatures, and it’s hard to disagree with that, especially when you look at them. However, the male sea otter can be aggressive at times. When it comes to mating, the male will hold onto the female otter and bite deeply on her nose and face, which can cause cuts and gouges. They will spin in the water until mating is complete, and the male will release his grasp on the female, who may sustain fatal injuries or, sadly, even drown afterward.

In a highly unusual situation, scientists observed some male sea otters in California’s Monterey Bay display violence toward and attempt to mate with another species: seals. They saw the animals dominate juvenile seals in encounters that led to their deaths. While the reasoning behind this behavior is uncertain, scientists believe that it may be due to a decline in the area’s otter population, particularly of females, that results in males having fewer mating opportunities.

10. Otters Are Endangered

river otter vs sea otter

The biggest danger to sea otters in the wild is oil spills.

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Otters are an endangered species, with five types listed by the IUCN as Endangered, another five as Near Threatened, and two as Vulnerable. That leaves us with one — the North American River Otter, which IUCN lists as of Least Concern. 

Threats to their existence include pollution, habitat destruction, overfishing (entanglement with dangerous fishing gear), and oil spills. Oil spills are considered the greatest danger due to their vulnerability to hypothermia upon contact with oil. 

They also face the threat of a cat parasite known as toxoplasmosis, often found in cat droppings. 

The photo featured at the top of this post is © iStock.com/pr2is


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