All About Sea Otters

FLORA LICHTMAN: This is Science Friday. I’m Flora Lichtman. Last month there was a viral animal story I cannot stop thinking about. A rogue sea otter was stealing surfboards off the coast of Santa Cruz, California, biting chunks out of boards and even catching a few waves.

SPEAKER: A five-year-old female who’s been stalking surfers in this area for months.

FLORA LICHTMAN: The culprit’s name– Otter 841. She remains at large. Up next, the 411 on Otter 841. Who is she, and why is she taunting surfers?

Plus, a deep dive into all things otter. Do they actually crack shells with rocks? Do they really hold hands? Here to separate otter fact from fiction is my guest, Jessica Fujii, Sea Otter Program Manager at the Monterey Bay Aquarium based in Monterey, California. Jessica, welcome to Science Friday.

JESSICA FUJII: Thank you. I’m so excited to be here.

FLORA LICHTMAN: OK, so let’s start with 841. Who is this surfboard-stealing otter? Do we know anything about her?

JESSICA FUJII: So this particular otter has a little bit unique history. Her mom was actually one of these pups that had been orphaned and needed to be rescued and cared for, so she went through what we call our surrogacy program, where we pair orphaned sea otter pups with our resident adult female sea otters. And we’re doing this so that they are forming that mother bond and able to provide– teaching those essential skills for survival with minimal human interaction. And that has been really key to our success in being able to have these animals return to the wild and act like wild otters.

FLORA LICHTMAN: So it was 841’s mom who was adopted by one of your otters, is that right?

JESSICA FUJII: That’s exactly right. And so her mom was successfully released to the wild. And unfortunately, in her case, we know she was illegally fed by people out on the water. And when that happened, that led to her needing to be brought back. It was no longer safe for her to remain in the wild.

And when she was in our care, we learned that she was pregnant. And so the idea was to be able to have her give birth in an animal care facility– this was with one of our partners– and then have that pup actually raised by her biological mother. And that pup ended up being 841 with the intent of 841 still being able to go back into the wild.

So in many ways, she actually had less interaction with people than many of our other surrogate-reared otters, but all of those protocols to minimize human interaction were still followed. And so 841 came back to us just prior to being released, so she was able to socialize with other sea otters, receiving care. And then, like I mentioned, in 2020, she was successfully released back to the wild.

FLORA LICHTMAN: So do you have a theory? What is with the surfboard thing? Why is she stealing surfboards?

JESSICA FUJII: Yeah. This particular behavior is very unusual, and also the level of persistence and aggressiveness that comes along with this is really not something we’ve seen in quite a while.

FLORA LICHTMAN: This is not a typical otter shenanigan is what I’m hearing?

JESSICA FUJII: No, no. Definitely not.

FLORA LICHTMAN: This is just unique to her it sounds like?

JESSICA FUJII: Yeah.

[LAUGHTER]

This particular focus on surfboards, particular types of surfboards.

FLORA LICHTMAN: Really? What, she has a specific type?

JESSICA FUJII: Particularly ones that have a softer top are ones that she’s seems to particularly going after. We don’t know why that is. There’s nothing that occurred while she was in care with people that would have led to that.

So based on the few other instances we have seen, being fed can lead to these types of associations. And then, in some cases, if a female otter is pregnant, when she’s going through those hormonal changes, that leads to unusual behaviors. We don’t know if either of those are the case with 841 or if there’s something else entirely going on.

FLORA LICHTMAN: Hmm? You know, the social media version of this story, and like the “me” version of this story, was like, “this is hilarious” and “you go, girl, otter.” But what is the otter scientist angle on this story?

JESSICA FUJII: Yeah. So from all the members of the different agencies and the aquarium that have been monitoring this otter, we’re concerned. We’re concerned about what this could mean for her health. If there is something abnormal going on in her that is causing these behaviors. But as well as concern for safety of the public.

FLORA LICHTMAN: Really? I think of otters as so cute.

JESSICA FUJII: And many people do, and that is part of the problem. You know, people don’t think of them as wild animals. They think of them as kind of teddy bears because they have so much fur. They have that very charismatic face.

But they have jaws and teeth designed to be able to crush hard-shelled prey that they need to eat. And so if they chose to turn that skill onto someone’s arm or someone’s leg, it could cause significant damage. And they also can have diseases that could be passed on to people, so that close proximity, that potential for harm is something that we don’t want to take too lightly.

FLORA LICHTMAN: So how do you prevent the otters that you’re caring for, rehabilitating from getting too comfortable with people? What do you do to make sure that the otters don’t see people as animals they want to approach?

JESSICA FUJII: Mm-hmm. Yeah. So a lot of work has gone into this, and the main things that we do are, at key points where there could be positive associations, we’re doing everything we can to disguise our form. So this is wearing dark ponchos to disguise our body, face shields so they don’t see our face.

FLORA LICHTMAN: Like a Darth Vader mask? What should I picture?

JESSICA FUJII: Exactly that. That’s exactly what we call our disguises is our Darth Vader costume. Yeah.

FLORA LICHTMAN: [LAUGHING] Just a wild guess. Amazing. OK.

JESSICA FUJII: And then we also don’t talk while we’re around the otters, especially doing any close proximity grooming of the young pups before they’re placed with their surrogate mothers. And so all of that combined really helps keep that distance emotionally, physically between the people who are providing the care and the animals.

FLORA LICHTMAN: You’re not like, (BABY TALK) oh, what a little cute otter. Love you. (REGULAR VOICE) Like, that’s probably not–

JESSICA FUJII: Absolutely not.

[LAUGHTER]

FLORA LICHTMAN: So I want to dive into sea otter science, generally. Surfboards aside, I feel like otters are having a little bit of a moment, at least on my Instagram Reels, but I want to check some facts with you. So let’s start with otter cuisine. What do otters eat, sea otters eat?

JESSICA FUJII: Yeah, so sea otters eat a wide variety of prey items, mostly different invertebrate prey items that they can find on the sea floor. So this can be anything from urchins, abalone, crab, but also snails, fat innkeeper worms, clams. Just depending on their environment. But we’ll also see that, depending on the location, otters might develop favorites. They’ll specialize on a subset of the different prey that are available and become really good at eating those particular prey items, finding them, getting them opened quickly.

FLORA LICHTMAN: Yeah. I mean, that’s the thing I wanted to ask about. Getting them open. I mean, it’s not trivial to open. Anyone who’s tried to shuck an oyster knows that shellfish are not trivial to open. Do otters actually use tools like rocks to do it? How do they do it?

JESSICA FUJII: Yeah. Some of them will definitely use tools, and they’re really quite skilled at it. So they’ll often find a rock on the sea floor and bring it up to the surface. One of the cool things about being able to study sea otters is that they actually bring all their food up to the surface to eat, so we can directly watch and observe what they’re eating and how they’re eating it. And so if they bring up a rock, they’ll often place it on their chest, and then they’ll hold the food between their paws and smash it up against that rock to break open that shell, and then they can get the softer meat that’s inside.

FLORA LICHTMAN: You know, we hear about crows and monkeys using tools, and I feel like that’s like a big deal when an animal uses tools.

JESSICA FUJII: Yeah. I mean, that list of non-human animals and non-human primates that are using tools is growing, but I think it’s still a really fascinating area of study to understand what problems are these animals trying to solve and how are they able to do that?

FLORA LICHTMAN: How much shellfish does it take to power an otter?

JESSICA FUJII: So an otter typically needs to eat about a quarter of their body weight every single day, and that’s just for survival. So it takes a lot of food for them to survive.

FLORA LICHTMAN: Why? Why do they need so much food?

JESSICA FUJII: Yeah. So unlike pinnipeds, so seals or sea lions or whales and dolphins, sea otters don’t have blubber to help keep them warm. They rely on their thick fur but also having a really high metabolic rate. And so to feed that kind of energy that they need to stay warm, that takes a lot of food.

FLORA LICHTMAN: Wow. Are they constantly foraging? I feel like this would be a lot of trips to the bottom of the sea if you’re picking up one clam at a time.

JESSICA FUJII: Yeah. So how much they need to spend during a day to get that amount of food can vary depending on prey availability, and so it can be anywhere between 25% to almost 50% of their day that they spend foraging. And then, when they’re not doing that, they really need to be able to rest in order to conserve the energy that they just gained.

FLORA LICHTMAN: Doing that back float.

JESSICA FUJII: Mm-hmm. Yeah.

FLORA LICHTMAN: Do they have any food storage techniques?

JESSICA FUJII: So they’re known to have what is kind of affectionately called their pocket. Their fur is very loose so that they can groom all of it, and that includes this extra portion of skin and fur underneath their armpits. And they’re able to use that extra portion of skin to hold food. So often we’ll see, if an otter comes up from foraging, they’ll have maybe one prey item in their paws, and then they’ll roll, and all of a sudden there’s a new clam that they’re holding, and they actually pulled that out of that pocket.

FLORA LICHTMAN: Out of their armpit pocket?

JESSICA FUJII: Yeah, exactly.

FLORA LICHTMAN: Where they store their snacks.

JESSICA FUJII: Mm-hmm.

[LAUGHTER]

FLORA LICHTMAN: Yum. How many clams can they fit in there?

JESSICA FUJII: So we’ve never really measured it, but just from my experience of watching sea otters, we’ve seen probably an otter with smaller clams have three or four at a time. When it’s been smaller snails, like turban snails, I’ve seen them have up to a dozen snails at one time that they just keep rolling and pulling out.

FLORA LICHTMAN: Otter pelts were once a big thing, right? It was part of why otters were almost hunted to extinction. Is their fur special?

JESSICA FUJII: Yeah. So their fur is the densest fur of any mammal. They can have over a million hairs per square inch, and so this keeps them very warm. And this was also, as you said, why they were overhunted for their pelts in the 1700 and 1800s. And then their pups have an even denser coat that makes them more buoyant when they’re first born, and that’s a great evolutionary adaption to being in the marine environment.

FLORA LICHTMAN: I’m Flora Lichtman, and this is Science Friday from WNYC Studios. If you’re just joining us, we’re talking about sea otters with Jessica Fujii from the Monterey Bay Aquarium. Well, yeah, let’s talk about the pups. So when they’re first born, can they dive and swim and do all the things that an adult otter can do?

JESSICA FUJII: When a pup is first born, it’s incredibly dependent on its mother for everything. So they don’t really swim. They definitely cannot dive.

So having that coat that is so buoyant allows them to float at the surface while Mom might need to dive down to grab food, and the pup can still just be resting at the surface. And then, slowly, as they age, that coat will shed, and they’ll get their more adult-like coat. And during that transition, we’ll actually see them trying to start to dive, but they’re still too buoyant, so they just pop right back up like a little cork.

FLORA LICHTMAN: I’ve heard something that seems like it cannot be true, which is that baby otters get put on kind of a kelp leash by their moms. Is there any truth to that?

JESSICA FUJII: I don’t think we’ve ever called it a leash, but we will see– moms will either place their pups in the kelp or maybe even wrap them up a little bit, and that keeps them from drifting off too far. So when a mom needs to forage, you know, she needs to get that 25% of her body weight of energy, plus potentially even more to provide to the pup, she needs to be able to dive down to the surface, come back up, make sure her pup is OK. So having it stay in the same spot can be really helpful for that, so we will see them purposefully put their pup in a kelp area to keep them in place.

FLORA LICHTMAN: Kelp, nature’s playpen. OK. Here’s the one I really need you to tell me if it’s true. We have to talk about the hand-holding thing. This seems like their most adorable trait. I feel like I’ve seen many videos. Even this morning I saw a picture of two otters holding hands. Does this happen?

JESSICA FUJII: Yeah. So unfortunately, I will have to burst some people’s bubble on this. Those two otters that you saw are living very happy lives in an aquarium.

FLORA LICHTMAN: [LAUGHING]

JESSICA FUJII: And so pretty much every photo and video that we see of this are of those particular otters. So it is something that they do, but in the wild, it’s not something that we see, adult animals just holding on to each other. You know, we will see the moms and pups holding on to each other, but beyond that, it’s really not something we see in the wild. We will see them “raft up” is what we call a group of otters resting together. So they might be in the same kelp bed together, but they’re not actually linking paws in order to stay together.

FLORA LICHTMAN: Ah! Bursting everybody’s bubble on a Friday afternoon.

JESSICA FUJII: Unfortunately, yes, but hopefully there’s so many other interesting things about sea otters to learn about that it’s not that much of a let down.

FLORA LICHTMAN: No. I agree. I agree. There’s too many other cool facts. Before we let you go, what’s the plan with Otter 841? Will she remain at large? Are people trying to capture her?

JESSICA FUJII: So we’re still monitoring her and working with the state and federal agencies. And based on environmental conditions, based on her behavior, they are making assessments on whether or not it is feasible to attempt a capture and whether or not it is still needed. So at this point, she is still being monitored. And as of today, she is still out in the wild.

FLORA LICHTMAN: That’s all the time we have for today. I’d like to thank my guest, Jessica Fujii, Sea Otter Program Manager at the Monterey Bay Aquarium based in Monterey, California. Thank you for joining us today.

JESSICA FUJII: Thank you so much for having me.

FLORA LICHTMAN: If you want to see some pictures of sea otters, go to sciencefriday.com/otters. Here are some of the people who helped make this show happen. Our Digital Producer is Emma Gomez.

Diana Plasker is our Experiences Manager. Santiago Flórez is our Community Manager. And Ariel Zych is our Director of Audience. BJ Leiderman composed our theme music.

If you missed any part of this program, or you’d like to hear it again, subscribe to our podcasts, or ask your smart speaker to play Science Friday. You could email us too. The address is scifri@sciencefriday.com. I’m Flora Lichtman. Have a great weekend.

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