Why Do Sea Otters Hold Hands? Rafting and Sleeping Facts

Why sea otters need to stay in place while they rest

A sea otter spends almost its whole life at sea. It eats, grooms, sleeps and even gives birth in the water, floating on its back thanks to large lungs and the air trapped in its dense fur. There is no bed to return to, only open water that keeps moving with the tides, wind and currents.

A sleeping otter usually lies on its back with its front paws folded on its chest or pressed over its eyes and its hind feet held out of the water. In this position it can doze for long periods, but it also drifts. An otter that drifts away from its group, its feeding grounds or a sheltered bay may end up in rougher water or have to swim back, wasting energy that is precious for an animal that must eat about a quarter of its body weight every day to stay warm.

Holding on to something, whether kelp, another otter or, in a few California harbors, a boat fender, solves the problem. The paw-holding seen in videos is one version of this anchoring habit.

How often do sea otters really hold hands?

Nobody has a reliable figure for how often wild sea otters hold paws. Scientists who study sea otters describe kelp wrapping and resting in close groups as the usual way to stay in place, and paw-holding as something seen now and then rather than every night.

The behavior became world famous in 2007, when a video of two sea otters at the Vancouver Aquarium floating side by side with their paws linked drew millions of views. One of the pair, Nyac, had survived the Exxon Valdez oil spill in Alaska in 1989. Captive otters live in calm pools with no kelp to grab, which may help explain why paw-holding is seen more often in aquariums.

In wild rafts, otters often float so close together that they touch and bump into each other. Some brief paw contact is probably common, but long hand-holding sessions like the famous video are not the normal way wild otters sleep.

Wrapping up in kelp: the natural seat belt

Giant kelp and bull kelp are large brown seaweeds fixed to the seabed by root-like holdfasts. Their long, floating stems and blades form a canopy at the surface, which makes them an ideal anchor. A resting otter rolls over several times in the canopy so that the fronds wind around its body, then falls asleep held loosely in place.

A kelp canopy also damps small waves and offers some cover, so kelp beds are favorite resting spots. Mothers use the same trick for their young: before diving for food, a mother may wrap her pup in kelp so it does not float away while she is underwater. Where there is little kelp, as in some estuaries, otters rest in sheltered water instead. Their kelp forests depend on otters in turn, as explained in Why are sea otters a keystone species?

Rafts: how sea otters rest in groups

Although each adult forages alone, sea otters gather to rest in groups called rafts. A raft typically holds 10 to 100 otters, and in Alaska rafts of more than 2,000 have been recorded. Being in a group may help otters spot danger, and floating close together keeps them from scattering.

Rafts are usually single-sex. Males gather in male areas, often in larger groups, while females and their pups rest in separate areas where territorial males patrol the edges during the breeding season. Long-term tracking of tagged otters in Monterey Bay suggests that rafts are not just random crowds: some individuals keep resting near the same companions year after year.

Sheltered places such as Morro Bay and Elkhorn Slough in California, and bays along the coasts of British Columbia and Alaska, are well known for their rafts.

Mothers and pups: the closest hold of all

The tightest bond in a sea otter’s life is between a mother and her pup. A newborn pup weighs only 1.4–2.3 kg (3–5 lb) and is covered in fluffy baby fur that holds so much air it cannot dive. For its first weeks it rides on its mother’s belly as she floats on her back, nursing, sleeping and being groomed there.

The mother grooms her pup for long periods to keep its coat dry and buoyant. If danger appears, she can grip the pup by the scruff of the neck with her teeth and dive with it. Pups start diving at around two months and remain dependent on their mothers until roughly six to eight months of age.

Males take no part in raising pups. The famous hand-holding is therefore not a sign of a devoted couple: sea otters are polygynous, and a courting male and female usually stay together only for the roughly three days of mating.

Myths and facts about sea otters holding hands

Myth: sea otters hold hands with their life partner. Sea otters do not mate for life: a male mates with several females and does not help raise the pups. Paw-holding is about staying put, not romance, and rafts are usually made up of otters of the same sex.

Myth: all otters hold hands when they sleep. River otters, including the Eurasian otter in Europe and the North American river otter, sleep on land in dens and resting places, so they have no need to anchor themselves at sea. See sea otter vs river otter for other differences.

Fact: sea otters do hold paws. It has been filmed many times, especially in aquariums, and it is a real way for floating otters to stay together. It is simply less common in the wild than kelp wrapping.