Difference Between Otter and Seal (With Table)

There are a ton of sea animals with various features and characteristics in the world. Some are extremely dangerous, some are small and cute, while some are harmless. Otters and Seals are two of such kind. Sea Otters and seals share many common things like both are mammals but the list of differences is quite long. The issue is that many people get confused with Otters and seals due to their same looking physique externally.

Otter vs Seal

The main difference between Otter and Seal is that Otter comes from the Mustelidae family whereas a seal belongs to the Phocidae family. Both of them belong to different families in spite of the fact that both are mammals, produce milk, and give birth.

A major difference comes into the picture when we see their strategy of keeping themselves warm. Otters use their dense fur as a way to keep themselves warm while Seals got a blubber deposit inside their skin. There are many more differences regarding their physique, features, and habits.

Comparison Table Between Otter And Seal

Parameter of Comparison




Otter comes from the Mustelidae family.

Seal belongs to the Phocidae family.

Strategy of being warm

With the help of their furs.

With the blubber deposit below their skin.

Place of Living

Spends most of their time in the water.

Spends most of their time on the land.


Otters usually like having invertebrates. 

Fish is the favorite food of Seals.

Physical characteristics

Otters have paws and external ears.

Seals have flippers and do not have visible ears.

Swimming ability

Otters are good swimmers.

Seals love to swim and are better at swimming than Otters.

Gestation Period

The gestation period for Otters is about 60 to 86 days.

Seals have 12 months as their gestation period.

What is Otter?

Sea Otters are the mammals that live in seas and oceans near the eastern north and the northern Pacific Ocean. A fully-grown sea otter weighs around 14 to 45 kg which makes them the heaviest member in the smallest marine animals in the Weasel family.

Unlike other mammals in the ocean, they do not have blubber under their skin. They have a very thick layer of fur over their body to protect them from cold. This thick layer of fur is the densest in the whole animal kingdom. They have the ability to walk, but they still prefer living in the oceans most of the time.

Below is the Scientific classification of the Otter:

  1. Kingdom: Animalia
  2. Phylum: Chordata
  3. Class: Mammalia
  4. Order: Carnivora
  5. Family: Mustelidae

Sea Otters were intensively hunted for their quality of fur from around 1700 to 1900 with the great fall in their population. This resulted in an international ban on hunting them via various programs. It is one of the smallest marine creatures but it is known for being the heaviest in the Mustelidae family. 

What is Seal?

Seals are commonly known as Pinnipeds. These are highly distributed and diverse carnivorous. There are a total of 33 extant species found for Seals. However, 50 plus extant species are described from the fossils found.

Seals weigh from 45 kg(Baikal Seal) to 3,200 kg(Southern Elephant Seal). Many species of Seal exhibit Sexual Dimorphism. Seals are highly agile and flexible due to their four limbs and streamlined bodies. These limbs of Seals are modified into flippers.

Below is the Scientific classification of the Seals:

  1. Kingdom: Animalia
  2. Phylum: Chordata
  3. Class: Mammalia
  4. Order: Carnivora
  5. Family: Phocidae 

Several species of Seals are very amazing at diving into deep oceans. Seals have a fat layer( also called blubber), under their skin that has the function of keeping them warm inside the cold water. Seals mate and give birth to their young ones on the land. They also come to land to escape from their hunters and predators like sharks. 

Indigenous people around the Arctic use the blubber, meat, and fur coats by hunting Seals. They are sometimes trained to perform various tasks and tricks and mostly kept in Captivity. They were once brutally hunted for these qualities but now are protected under International law.

Main Differences Between Otter And Seal

  1. However both of them are mammals, they come from different families. Otter belongs to the Mustelidae family whereas Seal comes from the Phocidae family.
  2. The technique of keeping themselves warm is also different. Otter, unlike other marine mammals, does not have blubbers and use their furs to keep themselves warm. On the other hand, Seals use their blubber deposits under their skin for keeping them safe from the cold water.
  3. Otters spend most of their time in the water while Seal roams more on the land. They mate, give birth, as well as protect themselves from the predators by moving themselves to the land.
  4. Otters are not fish lovers and usually live with feeding themselves with invertebrates whereas, Seals love fishes as their meals.
  5. Physical characteristics are also different for the two. Otters have paws while Seals have flippers. Otters have external ears while Seals’ ears are not visible.
  6. Both of them are good swimmers. However, Seals are better at swimming than Otters.
  7. Otters have their gestation period of around 60 to 86 days. On the other hand, Seals have their gestation period of 12 months.


Otters and Seals have many adaptations in common. Both of them are marine mammals and have lungs to breathe. Otters, as well as Seals, are both protected through the Marine Mammal Protection Act. It is not legal to capture or harass them by any person. 

However, there are various traits, behaviors, and characteristics which differentiate these two marine animals. For example, if we compare the swimming ability, the Seals win here because of their streamlined body and flippers. 


  1. https://www.ncbi.nlm.nih.gov/pubmed/9414481
  2. https://books.google.com/books?hl=en&lr=&id=eyJLlkpZ2-wC&oi=fnd&pg=PA1&dq=otters&ots=zFHEGQW7WK&sig=XaMnHPVwZhHzwyoEVYMP_7rvl70