10 Incredible Otter Facts

Written by Emmanuel Kingsley
Updated: August 15, 2023
© iStock.com/pr2is
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The otter, also known as a sea otter in many places, is a mammal with about 13 different species. Known scientifically as Lutra canadensis, 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

Otters are known by many people as sea otters. While that’s true, not all otter species are sea otters in a strict sense. We also have river otters, who are mostly found in freshwater and known for their swift movement on land and in water. They also swim belly down while paddling with their webbed feet. 

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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. 

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


2. Otters Can Be Described in Many Ways

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? 

river otter vs sea otter
A group of otters on land is called a “romp.”


3. Otters Are Voracious Eaters

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 and birds and their eggs.

Thanks to their healthy appetites, 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. 

What Do River Otters Eat?
Otters can eat up to 33% of their body weight in a day.

©iStock.com/Troy Levengood

4. Otters Have Favorite Rocks

We mentioned earlier that 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 usually under their left arm.

Cutest Animals: Sea Otter
Otters usually store rocks, which are used to crack open shellfish, in their underarm pouches.

©Kirsten Wahlquist/Shutterstock.com

5. Otters Sometimes Hold Hands While Sleeping

Some otters are known to hold hands while sleeping or resting and can be seen laying 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. 

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

©fred goldstein/Shutterstock.com

6. Sea Otters Have Incredibly Dense Fur

Otters have the thickest fur of all animals, period. Now, isn’t that something? 

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.

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


7. Only Female Otters Look After Pups

In the world of 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 called 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.

river otter and pup
Mother otters spend up to 14 hours per day looking for food for their pups.


8. Otters Are Swift Swimmers

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

otter swimming in clear water
Otters can hold their breaths for up to 4 minutes.

©Jonathan Chancasana/Shutterstock.com

9. Male Otters Can Be Aggressive

Otters are often considered some of the cutest sea creatures and it’s hard to disagree with that especially when you have a look at them. However, the male of the species 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, some male sea otters in California’s Monterey Bay were observed by scientists to display violence toward and attempt to mate with another species: seals. The animals were seen to 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.

river otter sticking tongue out
Despite their cute appearance, male otters display aggression during the mating process.

©iStock.com/Heather Burditt

10. Otters Are Endangered

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 is listed as of Least Concern. 

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

They are also threatened by a cat parasite known as toxoplasmosis, which is often found in cat droppings. 

river otter vs sea otter
The biggest danger to otters in the wild are oil spills.


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