Otter Facts

Otter Profile

Otters are carnivorous mammals living either in marine, aquatic or semi-aquatic environments and are related to weasels, badgers mink and wolverines. ¹

There are 13 species of otter on the planet today, the largest species being the giant otter and the smallest being the Asian small clawed otter. To give a comparison, the giant otter can reach up to 1.8m in length, whereas the Asian small clawed otter is usually around 70cm in length. The sea otter can actually grow to be the heaviest otter, with some males weighing up to 45kg!

Whether it’s a freshwater or marine environment that they are found in, otters are strong swimmers. They have powerful tails that act like a rudder to propel them through the water and solid webbed feet to help them remain streamlined. ²

In general, they have a long body with a fairly small head and compact limbs. Their ears are small and they have a short snout and long whiskers. The fur on their bodies is usually darker on top, compared to a lighter underbelly. ³

Otter Facts Overview

Habitat:	Rivers, lakes, wetlands and some in the seas of the pacific ocean
Location:	All continents apart from Australia and Antarctica
Lifespan:	10-15years
Size:	70-180cm long
Weight:	1-45kg
Colour/Appearance:	Fur ranging from grey to reddish brown with long, slim bodies. Relatively short limbs and a lengthy, muscular tail. Most have sharp claws and webbed feet.
Diet:	Generally fish, crustaceans and shellfish
Predators:	Depends on the part of the world they are found but their predators can include sea lions, killer whales, great white sharks, bears, coyotes, wolves
Top Speed:	The giant river otter has been known to swim at a maximum speed of 14kph
Threats:	Humans – fur trade; Pet trade (specifically Asian species); Pesticides and pollution in waterways; Conflict with fishermen and their equipment
Conservation status:	10 species endangered; 2 species vulnerable

Within the 13 species of otter there is the giant river otter, the North American river otter, the Eurasian otter and the African clawless otter to name some of the more well-known species. ⁴

Some of the less well known are the hairy nosed otter, the giant otter and the spotted necked otter. Some species are more prevalent and some are quite rare, such as the hairy nosed otter, found in South-East Asia and at one point was thought to be extinct.

They are a semi-aquatic mammal that can be found in wetlands, lakes, rivers, swamps, coastlines and oceans but can also spend time on land. They inhabit dens that are dug into banks, or reused from other animals such as beavers, close to the water.

These are made up of an intricate set of dry tunnels and chambers. These are usually where mothers go to have their young. The sea otter is a bit of an exception, spending most of its time in the ocean and not on land at all.

It has been observed that the Eurasian otter lives a more solitary lifestyle, only coming together to mate, while the marine otter has been seen to live in a monogamous pair. The giant otter, the African clawless otter and the North American river otter have been seen to live in a more extended family group situation.

This said, the social structure within a species can vary depending on where they are found.  It can also vary depending on the time of year, how large the habitat is and how extensive food sources are.

Otters have a high metabolism and are incredibly active. To keep this up they generally have to eat a lot. Most species feed on fish and crustaceans.

Salt water otters feed on shrimp, sea urchins and shellfish, while river otters can also feed on mussels, crabs and even frogs. The Asian short-clawed otter also hunts birds and even rodents! It is thought that otters have to eat at least 25% of their body weight each day to keep going. ⁵

Interesting Otter Facts

1. Some species have poo that smells quite special.

Otter faeces is so special it actually has its own unique name ‘spraints’. It is thought that because of all the fish that some otters eat, it is this that gives the unique odour. Some scientists have compared it to the smell of violets.  Otters use their faeces to communicate with one another.

2. Sea otters nap in the water but don’t float away

Sea otters are famously known for wrapping themselves and their young up in kelp in the ocean to help stop them from drifting away while they are napping. Some even intertwine their feet with one another to keep anchored.

3. Sea otters are the only species that gives birth in the water

Most otters will give birth to their young in dry dens located near the water. However sea otters are the exception to this, actually giving birth in the water.

They hold their young on their fronts, while they float on their backs. This is where they nurse them too. When the mothers need to go off and feed, they will find a safe space for the young to be left, usually on land.

4. Sea otters help kelp forests

Sea urchins eat kelp, sometimes consuming so much that the kelp forest is irreparably damaged. Sea otters eat sea urchins, meaning that there aren’t so many in the ecosystem.

Sea otters help keep things in balance and are known as a keystone species, having a big impact on their environment. As well as being such a help to kelp, sea otters are pretty amazing in the fact they have learnt how to use stones to crack open mussels, doing this even while floating on their backs.

5. Otters have incredibly thick coats

Otters do not have a layer of blubber to help keep them warm in the water like some animals. Instead they have an incredibly thick coat, the thickest of any animal. Some species have around 1million hairs per square inch of skin!

The fur has two layers, the top being waterproof. This stops water penetrating to the skin, helping keep the otter dry and warm even in the water. They spend a lot of time grooming their fur to keep it in good condition.

6. They can close their nose and ears

Otters can close both these orifices when diving underwater to help keep the water out of them.

7. Otters have a variety of predators, depending on where they are found.

The sea otter is predated upon by sharks, killer whales and even bears. The giant otter in the Amazon can be prey for jaguars and caiman (although they do at times fight back). Congo clawless otters can be prey for crocodiles, pythons, eagles and leopards, however they are mainly active at night and remain vigilant to help protect themselves.

8. Many populations of otters are declining around the world

One of the main threats to otters used to be people hunting them for their fur, which was popular in the fashion industry. However one of the main threats to otter populations today is actually pollutants and chemicals such as pesticides in waterways.

9. Giant otters are very vocal

The giant otter is a pretty social animal, generally living in a group consisting of a breeding pair and their offspring from different litters, each having different roles within the group. Even the young will ‘babble’ to one another. One study showed that adult giant otters have 22 different distinct vocalization types and the young 11 types.

10. There are many names for a group of otters

A group of otters can be called a bevy, family, lodge or a romp. However when in water a group of otters is known as a raft.

11. Gestation time is linked to size

With smaller otter species the gestation time for young can be as little as 2 months. However with larger species it can be up to five. Female otters usually give birth to between 1 and 3 pups usually in their dens (with the exception of the sea otter). Pups usually leave their mothers at 1year old and become sexually mature at 2-5years old depending on the species.

Otter Fact-File Summary

Scientific Classification

Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Carnivora
Family:	Mustelidae
Genus:	7 genera

 

1. “Otter Species”, Otter Specialist Group.
2. “Otters”, National Geographic.
3. “13 Types Of Otters And Where They Live: With Facts And Images”, Outforia.
4. Alina Bradford (2016), “Facts About Otters”, Live Science.
5. Marie-Loup Lélias (2021), “Social organization of otters in relation to their ecology”, Oxford Academic.