Our significant Otters: 10 fascinating facts about the Sea Otter

Ever wondered where a sea otter keeps its favourite rock? If so this is this is the article for you.




1. Fat Free

Sea otters are the only marine mammal on the planet that has no blubber. Without blubber for insulation against the freezing waters they inhabit sea otters rely on incredibly dense fur to keep themselves warm. This coat has two types of fur in it; underfur and guard hair. Air trapped between these two layers stops the otter’s core temperature from dropping to dangerous levels. With nearly 1 million hairs per square inch this is the densest fun of any animal.


2. Big Eaters


Sea otter need to eat a third of their body weight every day just to keep warm.

A warm coat is not the only adaptation sea otters have to keep the icy waters at bay, they also have an incredibly high metabolic rate around two or three times that of most mammals of a comparable size. A high metabolic rate keeps the otters warm in a similar (but not identical) way to the warming effect we experience when we exercise; the only problem with this is it gives otters quite an appetite. Imagine if you spent all day everyday running at an easy jog, you’d feel pretty hungry by tea time! To cope with this huge energy demand sea otters eat around a third of their body weight daily, equivalent to a 70kg human eating 2000 slices of bread.


3. Sea Otters have pockets

Believe it or not sea otters have pockets. Under each arm and extending on to their chest are loose flaps of skin that can be used to store small objects. The otters use these for carrying food they find to the surface for consumption and also as a safe place to keep their favourite rock…


4. Tool Users

Sea otters are amongst a small and select group of mammals to use tools. They have been observed using their rock as an anvil to break open shellfish. This is done whilst the otter is floating on its back with the anvil resting on its chest and the shellfish clamped in its paws. Otters also regularly use their rock as a hammer to pry stubborn abalones off rocks deep under water. Each otter’s rock is unique and is kept until it breaks.


5. Sensitive type


Sea Otters hold paws to prevent drifting apart whilst they sleep.

Sea otters primarily use their sense of touch and their paws to hunt for food. This involves delicate work such as picking snails off kelp and digging for clams but also catching fish. The sea otter is the only marine mammal to catch fish using its paws not its mouth. As well as using their dexterity to hunt, forage and use tools sea otters also use their paws to hold hands whilst asleep. This prevents an individual from drifting off whilst they doze. A group of otters doing this is called a raft.


6. Well groomed

To keep their life saving fur in good condition sea otters spend any free time meticulously cleaning themselves. Via a combination of baggy skin and a flexible skeleton all of the fur can be reached to ensure a thorough clean. Maintaining their amazing coat consists not only of cleaning but also of untangling knots, removing malting fur, rubbing the fur to squeeze out water and introduce air, and even blowing air into the fur to ensure it remains waterproof. Because otters are so dependent on cleanliness they are highly vulnerable to oil spills. Even a small amount of oil will cause hypothermia within hours.


7. Not good enough to eat


Sea otters are inedible to most predators.

Sea otters have very few natural predators. This is mainly due to their pungent scent glands. Even the ocean’s largest predators such as orcas find them inedible due to the terrible taste of these glands.


8. Keystone Species

Sea otters are what conservationists refer to as a keystone species. This means they have a much more important role in maintaining the eco system they inhabit than their size and numbers would initially suggest. In this case the otters’ control of the sea urchin population (which feed on kelp) keeps the kelp forests from being destroyed. Areas without sea otters have turned into ‘urchin barrens’ –areas with no kelp but hoards of sea urchins.


9. Heavy Drinker

Whilst most of a sea otter’s water demand can be satisfied from the food it consumes they still need to drink some water. Incredibly this is fulfilled by drinking sea water! Thanks to large kidneys the salt can be excreted and the otter never needs to leave the water in search of a drink.


10. Back from the brink


The future looks bright for sea otters.

From approx. 200,000 individuals in the early 18th century to under 1% of that in 1910 and now back to 100,00 individuals it’s fair to say sea otters have truly bounced back from the brink. The reason for this population boomerang is the fur trade. As I mentioned earlier sea otter fur is amazing stuff and was consequently prized by humans for its warmth. This soon led to dramatic over exploitation which nearly wiped out the sea otter. Farsighted legislation and a committed conservation effort have led to the recovery of this amazing species and is regarded by many as one of marine conservation’s great success stories. It goes to show that conservation is not always about limiting losses and that with the right methodology and resources human damage to an animal population can be reversed even in what appears to be a species’ final moments.


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Asher Collins

Asher Collins

Asher Collins is a student and author based in the UK. He writes about conservation because he thinks vultures are underrated, pistol shrimps are actually quite interesting, and the world could do with a few more Kakapos. He also writes for Farsight Conservation.
Asher Collins

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