Chapter 7: Furry New Friends

“Caretakers watched closely as 501 was tested by these new experiences and they looked for evidence of her ability to adapt to life in the wild. These experiences had opened new possibilities in her life, but 501’s final test would close a chapter forever.” 

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Little by little, 501’s world expanded. It was now the 19th of August, fifteen days since the introduction to Toola, the first otter she had a face-to-face encounter with since her birth mother. The mother and pup bond cemented, it was now time for 501 to have her first play date.

“We like to give the surrogate-pup combos exposure to each other because that’s a pretty natural social mixing out in the wild,” Karl Mayer said. “The mothers with the pups are in the same areas together, and oftentimes the same mothers with the same pups are encountering each other multiple times throughout the course of the pups’ development.”

Find out more about sea otters in nature from a scientist


505, an abandoned male pup taken in by SORAC shortly after 501’s arrival, had been paired with Mae, another of the Aquarium’s four surrogate mothers. The two had bonded in much the same way as Toola and 501.

The four otters, Mae, Toola, 505, and 501 were put together in a freshly cleaned tank. At first both pups were inquisitive, breaking away from the safety of their mothers to investigate. But much like researchers observe in the wild with biological mothers, the surrogates were protective and weren’t keen to let their pups take off alone.

501 and Toola are joined by 505 and Mae

The SORAC caregivers, having expected this kind of give and take as the four explored their new social boundaries, still monitored their behavior very closely. The situation could change quickly with four animals together.  When the caretakers were convinced that the otters had accustomed to one another without incident, the four were allowed to stay together for days and even weeks at a time.

Many of 501’s major developmental milestones coincided with the time she was introduced to Toola at week 8. But some skills, like opening clams and mussels, were easier to learn when someone else was around to show her. Many of these skills developed four to seven weeks later, at 12 to 15 weeks.

501’s adult canines came in over the course of four weeks, around weeks 14 through 18, and this was one of her last significant milestones.  Armed with stronger chompers, 501 had nearly become an adult.

Catching and eating her own live crab—with its snapping, defensive claws —was one of the last tests of 501’s skills. At first it was a painful challenge, but with adult canines and Toola’s modeling, she became an efficient predator of the most formidable prey. As a scout receiving her final merit badge, 501 had gained all the hard skills she could from her time at the Aquarium. 

From this moment on, caretakers became less concerned about milestones like these, and more concerned about giving 501 experiences that would make her looming transition to the wild less of a shock.


501 had always fed on seafood that met sustainability criteria set by the Aquarium. Restaurant-grade surf clam, local squid, and white shrimp from the Gulf formed the bulk of her diet during captivity. She also got a regular chance at live prey, such as Manila clams, blue mussels, and cancer crabs.

However, in the wild, sea otters feed on dozens of different prey species. She’d have an array of creatures to feed on, if she could find and catch them,. An abbreviated course in identification might give her an edge. Caretakers collected some of the more common wild prey – shore crabs, innkeeper worms, harbor mussels – and tossed them in her tank during mealtime.

Sea otters often use rocks to bash open shells

501 had mastered diving weeks ago, but master or not, she couldn’t dive very far. SORAC’s rooftop tanks are only a couple of feet deep. The exhibit tank where otters were kept when on display at the Aquarium, however, holds more than a full story of water. After Aquarium guests had gone home, 501 and Toola were netted from their rooftop tank, rolled across the Aquarium in a pet carrier, and plopped in to the exhibit tank for 501’s first field trip. 

The depth gave 501 freedom to explore a new world. With luck, it was preparation for an even bigger world back in the wild.

501 gets a chance in some deeper water

Three weeks later, 501 and Toola got another chance to flex their muscles in the deep water. But this time they had company. 505, Mae, and an exhibit sea otter named Kit joined them in a raucous melee.

Caretakers watched closely as 501 was tested by these new experiences and they looked for evidence of her ability to adapt to life in the wild. These experiences had opened new possibilities in her life, but 501’s final test would close a chapter forever. 

Look how much 501 weighs now See how 501 continues to progress
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Watch the 501 Story

Want your own sea otter party? Watch Otter 501 with your family! Order the Otter 501 DVD, snuggle up with your furry and not-so-furry friends, and enjoy the show. Let us know if you’d like to plan a public screening of Otter 501.

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Special Features

This Page All
  • AAS: MS In Nature

    Ask a Scientist: Michelle Staedler – Sea Otters in the WildFind out more about sea otters in nature from a scientist

  • Mae and 505

    Video Clip: Mae and 505501 and Toola are joined by 505 and Mae

  • Dining with Tools

    Video Clip: Dining with ToolsSea otters often use rocks to bash open shells

  • Underwater Otter

    Video Clip: Sea Otter Exhibition Tank501 gets a chance in some deeper water

  • Growth Chart 4

    Growth of Otter 501 to 181-days OldLook how much 501 weighs now

Chapter 1: The Ocean is Cold but Mom is Warm

Chapter 2: Less than Ideal Rescue

Chapter 3: Emergency Treatment

Chapter 4: Species in Danger

Chapter 5: No Substitute for Mom’s Cooking

Chapter 6: The Surrogate

Chapter 7: Furry New Friends

Chapter 8: Release

Chapter 9: A Wild Sea Otter

Ask a Scientist: Michelle Staedler – Sea Otters in the Wild

What is a day in the life of a sea otter in the wild like? 

Michelle Staedler: A typical sea otter day begins with foraging in the early morning for a few hours. This is followed by a little grooming, before resting for several hours in the middle of the day, usually in a kelp bed. Later in the afternoon, around 3:00 or 4:00 pm, they start feeding again for a few hours. After this feeding, they rest again for a period of time and generally forage one more time during the night.

Otters are individuals, just like people. A typical otter will look for food for two or three hours at a time during a feeding bout. We have also watched otters that will sleep all day and have only one very long feeding period of up to seven hours at night. So, it just depends on which otter you are watching. Female sea otters caring for pups will spend a little more time looking for a meal, especially when the pup gets older.

So pups are still learning the skills they will need when they are weaned and on their own?

MS: Otter pups learn how to search for prey from their mothers; and once on their own, they often prefer to eat the same foods that mom taught them to eat, like clams or crabs. But as they get older, they improve their feeding skills through practice. Sometimes they may discover new prey items that require a different technique to open a shell to get through the exoskeleton.

You mentioned age categories. How do they relate to years?

MS: We have very small pups, or what you might call the neonates, at zero to three weeks of age. Small pups would be three to ten weeks old, followed by large pups that are greater than ten weeks of age, to whenever they wean. Usually the average weaning age is about six months but we’ve had some stay longer with mom, and certainly some separate a little earlier.

From six months of age to one year, pups are called juveniles, or immature. The one to three year olds are the sub-adults. Over three years are adults, and otters greater than ten years old are considered aged adults.

Can you describe a little bit about the grooming?

MS: Because otters have no large fat stores to keep them warm, they rely on their warm fur coats. This fur must be kept in top condition to prevent water from seeping in and getting close to their skin where they might get cold. When otters roll around and tumble in the water, rubbing their rear flippers and front paws together and along their bodies, they are grooming their fur. Sometimes when otters groom, people think they are “scratching.” 

Otters groom in preparation for foraging. You’ll see them start grooming—at first it’s very slow. They start to rub their fur with their forepaws, and twirl around a little bit, waking themselves up. They’ll start grooming a little harder, fluffing up their fur, trapping air in to help stay dry. This is followed by a couple of shallow dives, after which they return to the surface and rub their fur even more. Finally, they start diving deeper for food. In between a series of dives, when a prey item is brought to the surface and eaten, they might groom slightly before diving back down. It’s not the vigorous grooming that you would see when they’ve finished feeding, but a little touching up before the next dive. Once they finish a forage bout, they start to settle in to the kelp, groom more intensively, and get ready to go back to resting.

In situations where they are resting and are suddenly startled by a boat or kayak getting too close, they will dive quickly to avoid the threat, and not take time to fluff up their fur.

Video Clip: Mae and 505

It was time for 501 to meet some new sea otters. Mae, another surrogate mother, and 505 joined Toola and 501. Look for how protective the moms were during this encounter.

Video Clip: Dining with Tools

Very few animals have evolved and adapted to use even the simplest of tools, such as rocks. If you’re walking along the seashore in Central California and you hear the sound of rocks banging together in the ocean, chances are it is a sea otter smashing open a clam with its favorite rock.

Video Clip: Sea Otter Exhibition Tank

As the time drew near for 501’s release into the wild, she needed some experience with deeper water. So, when the Monterey Bay Aquarium closed for the night, 501 and Toola got to swim in the Sea Otter Exhibit’s deep tank.

Growth of Otter 501 to 181-days Old

After 501 and Toola’s introduction, 501 got weighed less frequently. The graph shows her growth to 181-days old.

Otter 501′s Development to 185-days Old