River Otter Vs Sea Otter! Differences You Ought To Know

Christian Mba
Feb 20, 2024 By Christian Mba
Originally Published on Nov 16, 2021
Giant river otter standing on log
Age: 3-18
Read time: 8.4 Min

What comes under the category of the most adorable creatures? Otters, of course!

Their cute faces and charming behavior aside, many of us find it difficult to distinguish between sea otters and river otters. What's the difference anyway?

Physical variations are the ones that can be noticed immediately. For instance, the stature of a sea otter is enormous compared to that of a river otter. The largest sea otter is still heavier than the largest river otter (the Giant otter) when it comes to weight. The maximum size of male river otters comes up to 30 lb (13.6 kg), while for male sea otters, it goes up to 90 lb (40.8 kg). Concerning fur types, river otters have short and sleek fur, while sea otters have distinctly long, fuzzy fur. Their coat is dense and warm, giving them the apperance of being fluffy.

If you like our article about river otter vs sea otter facts, then why not take a look at hairy-tailed mole and Gervais' beaked whale facts.

Differences Between Their Personalities

There is always confusion between adorable sea otters and river otters, but you can tell the difference by the physical features of each animal and, of course, their personality.

Sea otters are like the party animals of water bodies. They are intelligent, chatty, curious, and much more. River otters can be described as playful at best as they love sliding down icy or muddy slopes. Sea otters are usually out and about during the day. On the other hand, many otters are said to be nocturnal. They are more solitary in nature compared to their seafaring counterparts, though river otters are sometimes spotted in small family groups. Sea otters congregate in groups ranging from small to large. River otters prefer to avoid conflict, whereas sea otters are ready to confront and challenge at all times. The former is more territorial than the latter.

Mother otters also behave differently. For instance, sea otters keep their young ones nestled on their stomach as they float. This is done until they are capable and old enough to swim on their own. To keep the babies safe, the mothers are known to wrap them in kelp. That said, river otters keep their young ones safely by their side or in dens that are built by them on riverbanks. The dens made by otters are known as holts. Apart from these, they also use hollows under trees and old rabbit holes.

Concerning their swimming styles, river otters love to lounge around on riverbanks and swim with their bellies down. If otters are seen in float mode, and they are on their backs even when they are eating, they are definitely sea otters. There is a feeding hierarchy observed among sea otters by researchers. Smaller sea otters eat less desirable food, including discarded bits. The bigger otters end up taking food from the smaller ones.

What do they eat?

Sea otters eat slow-moving fish and invertebrates, including crabs, clams, mussels, and abalones, and they have the ability to fracture shells with their teeth.

Sea otters can consume up to 24.3 lb (11 kg) of food on a daily basis. In contrast, a river otter's diet consists of crabs, fish, frogs, and crayfish. Sea otters eat around 25-30% of their body weight, whereas river otters eat about 15-20%. Food preferences vary among individuals. They hunt alone or in pairs, and they find food in the water as well as on land. For instance, at times, they can travel around 10-18 mi (16-28.9 km) in search of food. Giant otters mainly eat fish and crabs.

River otters catch their prey using their teeth. Sea otters, on the other hand, use their forepaws to seize prey and bring it to the surface. They are also counted among the few marine animals known to use tools to obtain their food. For instance, they use a rick to dislodge mollusks and urchins.

A Southern Sea Otter cradles her pup

Where can you find them?

It is as easy as their names suggest. If you find an otter floating in a sea, it is a sea otter. If an otter is in a river, it is a river otter.

Sea otters are mostly found in the shallow coastal waters of the North Pacific Sea. Apart from the obvious, some river otters are found in wetlands and lakes. River otters go wherever they find fish, whether it be rivers, lakes, lagoons, ponds, or even oceans. That may be one reason why there are other places where river otters are found, apart from just rivers. Sea otters spend their life in seawater.

Sea otters are mostly found in areas where there is protection from the most severe ocean winds, for instance, thick kelp forests, barrier reefs, or rocky coastlines. They are native to northern and northeastern North Pacific Ocean coasts, from Alaska to Southern California. Sea otters are seen linking arms in single-sex groups known as rafts and also tend to rest together.

A typical raft consists of anywhere between 10-100 in number. On the other hand, in non-coastal water areas of every US state, you will find river otters. As long as the water is fresh or brackish with a tinge of saltiness, it is good enough for them to settle in. They inhabit water bodies less than 130 ft (40 m) deep. They can dive 300 ft (91.4 m) down into the water for food if needed. The only areas where they are not found are arid deserts and the treeless Arctic.

What kind of animals are they?

Otters are on top of the food chain as predators and are responsible for keeping the environment balanced. They are vital for the health of carbon-absorbing kelp forests as they prey on sea urchins that, in turn, feed on kelp. Thus, forests flourish where otters are present.

Sea otters are known to get attached to a stone and often keep it by hiding it in their armpit! They also juggle stones. River otters are ready to move when necessary. They move with the season to find more food. Sea otters are the greatest member of the weasel family and, at the same time, the smallest marine species in North America. Both river and sea otters are dark-brown in color, but the latter has a much lighter head.

A short tail indicates sea otters, while a long, circuitous one indicates river otters. River otters never float on their back, unlike sea otters who do it very often. Instead, they swim using a doggy paddle. River otters can effortlessly run on land, while sea otters are never even found on the surface. Concerning their family size, river otters have two to three pups per litter on average, whereas sea otters have only one.

Sea otters are slow swimmers, while their river-living counterparts are rather agile. The former can reach up to 5.6 mph (9 kph) underwater, while the latter, in North America, has a maximum speed of 8.7 mph (14 kph). It might be because river otters have to fight the strong currents of a river and catch their food and fish.

Did You Know...

Otters are probably the cutest animals. Otters are furry animals. You can tell the difference between sea and river otters by fur type. River otters are known to have short double-coated waterproof fur.

You will find that sea otters have the densest fur. Sea otters' fur is probably the densest fur in the entire animal kingdom. Otters love to swim in the water. You can find river otters around river banks, while sea otters are found in saltwater and rarely visit the land. You can distinguish between river otters and sea otters by considering the size of the animal. However, most otters have webbed feet. Sea otters are big and river otters are just small animals. Another fascinating distinguishable part of the otter's body is that river otters are dark brown, whereas sea otters are also dark brown in color but the heads of the sea otter are somewhere lighter.

This can be the easiest distinguishable area between river otters and sea otters. The swimming styles of both otters are remarkably different. River otters tend to keep swimming on their stomachs while sea otters swim on their backside. Sea otters are found to be floating on water while the river otters are 90% submerged inside the water. You can even point out the differences by taking a look at the tails of otters. River otters do have long and sharp tails. Sea otters have short tails. This is not all that has to be different about otters.

A river otter will have two or three pups in one go, while a sea otter would only have a single pup near a bay. Their nurturing styles are even different. River otters are found to keep their young ones in dens or always by their side near river banks. The sea otter's caring nature is the loveliest. A mother sea otter will keep her litter upon her stomach while floating and will do this until the baby grows big enough and learns swimming for itself. When you speak of the diet of a sea otter vs a river otter, there is quite the difference even though they are both aquatic. River otters are feed on crabs, frogs, crayfishes, and fish.

Sea otters are known to feed on urchins, clams, snails, mussels, and even abalones. Otters are indeed the most lovely and amazing creatures on earth. Even if both aquatic otters sound similar due to their names, they are relatively distinct from each other. They belong to different classifications and populations. You can look at them just as you look at different breeds of dogs. As mentioned before, one of the easiest ways to differentiate is where they are (sea or river) and how they look (large and fluffy or small and streamlined).

Here at Kidadl, we have carefully created lots of interesting family-friendly facts for everyone to enjoy! If you liked our suggestions for 'River otter vs sea otter' then why not take a look at 'Greater horseshoe bat', or 'Geoffroy's cat'?

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Written by Christian Mba

Bachelor of Science specializing in Computer Science

Christian Mba picture

Christian MbaBachelor of Science specializing in Computer Science

Christian Mba is an experienced blogger and content writer with over a decade of experience. He holds a Bachelor of Science degree in Computer Science from Nigeria and has a keen interest in Python programming. Along with his writing and blogging expertise, he is also an SEO specialist with more than six years of experience. Chris, as he is commonly known, has a passion for music and enjoys playing the piano.

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