Difference Between Beavers and Otters

Otters and beavers belong to the class Mammalia in biological classification. Beavers are large, herbivorous, semi-aquatic rodents in the northern hemisphere’s temperate climate.


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They are considered the second-largest living rodents after capybaras. These mammals belong to the order Rodentia and genus Castor.

There are two living species of beavers, the North American beaver (Castor canadensis) and the Eurasian beaver (Castor fibre).

Otters are furry, predatory animals of the Mustelidae family to which the weasels and badgers belong. They are semi-aquatic, aquatic or marine and are known for their playfulness, especially in the water.

They are found everywhere in the world except Australia and Antarctica. There are currently 13 living species of otters ranging from smooth-coated (Lutrogale perspicillata) otters to giant otters (Pteronura brasiliensis).

Key Takeaways

  1. Beavers are larger rodents that build dams and lodges in aquatic habitats, while otters are smaller, more agile mammals that swim and hunt in rivers and oceans.
  2. Beavers have large front teeth to cut down trees and build dams, while otters have sharp claws and teeth to catch fish and other prey.
  3. Beavers are primarily herbivores, while otters are carnivorous and eat various fish, mollusks, and crustaceans.

Beavers vs Otters

The difference between the beavers and otters is their nutrition mode, which also affects their behaviour. A beaver is a herbivore, while an otter is a carnivorous mammal.

Beavers vs Otters

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Comparison Table

Parameters of ComparisonBeaversOtters
Mode of nutritionHerbivoresCarnivores
Time partitioningNocturnalDiurnal
RegionsNorthern hemisphereEverywhere except Australia and Antarctica
BehaviourHardworking, territorial and live in a close-knitted family.Playful as they love splashing in the water and gambolling on the land.
MoultingBeavers moult during summer.Otters do not moult
IUCN Red list statusLeast concernedEndangered

What are Beavers?

Beavers are the large, semi-aquatic rodents of the temperate northern hemisphere. They have stout bodies with large heads and can range from 80 cm to 120 cm in body length.

Long chisel-like teeth help them cut down the trees and in digging. Their front feet resemble hands and help in manoeuvring their surroundings.

They are semi-aquatic and thus have webbed back feet, flat scaly tails and waterproof fur. Their colour may range from reddish-brown to almost black.

They are herbivores and eat tree bark, aquatic plants, brush (scrub vegetation), grass and sedges.


Beavers live in freshwater habitats like rivers, streams, lakes and ponds. They are good builders and affect their environment by building dams and lodges.

They use things from their environment, like tree branches, vegetation, rocks and mud, to create these structures.

They are classified as keystone species because of their impact on the environment and other species.


Beavers can live up to 7- 8 years in the wild and 24 years in captivity.


Beaver families have so much in common with human families. Adult beavers live in monogamous pairs with their young ones. Adults build structures and feed the young ones.

When parents are old, young beavers help parents build the structures and even help in raising younger siblings – just like humans.

Highly territorial- Beavers are highly territorial and even mark their territories using scent mounts made of mud, debris and castoreum (a substance excreted in urine through their castor sacs).

Beavers are good swimmers.

Nocturnal- Beavers are mostly active during the night. They sleep for almost 11 hours a day.


Beavers are hunted for their fur, meat and castoreum, which is used in medicine, perfume and flavouring.

In the 19th century, they almost got extinct, but their population bounced back, and now they are listed as the least concerned in the IUCN Red List.


What are Otters?

Otters are the adorably charismatic members of the Mustelidae family of members such as weasels, badgers and ferrets etc. Small, elongated-sized otters have a head-body length of around 60 cm to 180 cm.

They have short ears and noses, which they can close underwater. They have dense fur and long rudder-like tail.


Otters live in freshwater habitats like rivers, lakes and wetlands. Some species have adapted to live in the oceans, such as the sea otter and the smaller marine otter.

They do not build their own homes but use structures built by the beavers and other animals to give birth to their young ones.

They have webbed feet and a powerful tail making them a great swimmer. Their waterproof fur keeps them warm. This fur has no fatty layer but is the thickest of any other animal (a million hair per square inch).

Some cold-water species of otters have a high metabolism rate, which keeps them warm in the water.


They generally live around 16 years in the wild and can live up to 24 years in captivity.


Excellent hunters – Apart from being good swimmers, they are excellent hunters and hunt small fishes, crustaceans and other critters.

They have highly sensitive whiskers that detect the slightest change in the current and help them locate the fish. Some other species, like the sea otter, have learned to open the shellfish.

The sea otter keeps swimming on its back and hits the shellfish with the stone until it opens.

Unlike the busy beaver, otters are very playful and love splashing, hopping and running around.

Diurnal – Otters are mostly active during the day.

They use their vocals to communicate.


Otters are listed as endangered mammals on the IUCN Red List because of massive hunting for their fur. They are also getting affected adversely by pollution and pesticides.


Main Differences Between Beavers and Otters

  1. Beavers are herbivores, and otters are carnivores.
  2. Beavers are nocturnal, and otters are diurnal.
  3. Beavers are found only in the northern hemisphere’s temperate regions, while otters are everywhere except Australia and Antarctica.
  4. Beavers moult during summer, but otters do not moult.
  5. Beavers are famous for their industriousness and busyness, while otters are famous for their playfulness.
  6. Beavers are currently listed under the least concerned category in the IUCN Red List, while otters are listed under the endangered category.
Difference Between Beavers and Otters


  1. https://pdfs.semanticscholar.org/65e9/c16f5224532aff12ee87b673d39fba8aac59.pdf
  2. https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2907.2005.00067.x
  3. https://pubs.er.usgs.gov/publication/70189969
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