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Glistening dark bodies roll in the water. Light-furred faces pop to the surface, then dive back in. And slinky forms trade places between pool and rocks.

For someone without a trainer’s eye, Shedd Aquarium’s sea otters look an awful lot alike. And they seldom stay still long enough for you to try to discern differences. To help you figure out who is who, here are each otter’s key characteristics, or field marks, as wildlife biologists say.

A sea otter pup lies on its front amidst strips of blue fabric.


Cooper is one of two rescued southern sea otter pups that arrived at Shedd in July 2019. At a little over a year old, Cooper is already starting to get grey around the face, with a white chin and white eyebrows giving him a recognizable pattern to spot at Shedd.

But he was tiny when, in May 2019, he was picked up off the California coast by a kayaker who heard the pup's calls, thought he was abandoned and removed him from the location. In all likelihood, the pup had probably been "parked" in kelp by mom so she could hunt. The pup wound up with Monterey Bay Aquarium's sea otter rescue team, which returned to the site hoping to locate the mother. Because the rescuers failed to find any adult sea otters and the pup needed immediate nourishment, the decision was made to take him into human care, effectively eliminating the likelihood that the 2-week-old pup could ever be returned to the wild. While the kayaker's intentions were good, it is a reminder that the public should not intervene with wild animals, but instead call experts with their concerns.

A fluffy otter pup lies on its back with its arms raised above its head.


Southern sea otter Watson was rescued two days after Cooper, and the two infants became fast buddies at Monterey Bay Aquarium's sea otter nursery. You can tell them apart by their facial fur. Watson hasn't quite started growing the white facial fur characteristic of adult sea otters--for now, he retains his dark brown yearling fur.

When rescuers discovered Watson, after hikers reported a stranding, the pup was hungry, wet and shivering from hypothermia. No adult otters were in the area, and the pup was in such rough shape that rescuers immediately took him to the aquarium for triage. Watson was tangled in seagrass and covered in sand, leading experts to believe he had been separated from his mother during a recent storm and tossed by waves onto the beach. Without a mother to teach him survival skills, he needed a permanent home. Monterey Bay Aquarium asked if Shedd could take both pups. Today, while Cooper and Watson are still closely bonded, they play with younger adults like Luna.

Sea otter Luna's dark coloring and light-colored whiskers make her easy to pick out among the other otters.

At just a few days old, Luna was one of the tiniest rescues taken in by Monterey Bay Aquarium's sea otter experts.


At just a few days old, Luna was one of the tiniest rescues taken in by Monterey Bay Aquarium's sea otter experts. On Sept. 30, 2014, rescuers were called after the 2-pound pup's high-pitched cries had been heard along a rocky stretch of California coast. After four weeks of intensive care, Luna, who could not be returned to the wild, was welcomed at Shedd. The tiny, photogenic ball of fluffy fur and her rescue story caught national attention, and Luna appeared on two lists of cutest animals in the world. More important, she became an ambassador for her species. Although they used to be abundant, threatened southern sea otters are now only found in small populations along the California coast, where they are vulnerable to food limitation from human overfishing, warming ocean temperatures, severe weather and periodic climatic events, pollutants, diseases from land-based runoff, predation and human intrusions. The risk of a major oil spill also continues to pose a serious threat.

Once you know what to look for, you should be able to identify at least a few of the sea otters, even if they don’t stay in one place long enough for easy comparisons. If you happen to catch a training session, you can decode who they are by the unique hand-held shapes used to call them to station, the same as the dolphins and belugas have: Luna—yellow star; Cooper—green-and-blue bowtie; Watson—red-and-yellow cross.

—Karen Furnweger, web editor