Killer Whales Seen Making Kelp Tools To Scrub Their Backs

FLORA LICHTMAN: This is Science Friday. I’m Flora Lichtman. When you think about animals using tools, maybe Jane Goodall’s chimps come to mind, using a long blade of grass to get tasty ants from a nest, or maybe a crow using a windy twig to fish out a grub. But there’s more writing.

This week in the journal Current Biology, researchers describe a different use of tools in the animal kingdom in orcas, killer whales. But it’s not to get food. It’s for spa time. Joining me now to scrub through the research is Dr. Michael Weiss, research director at the Center for Whale Research in Friday Harbor, Washington. Michael, welcome to Science Friday.

MICHAEL WEISS: Thank you so much for having me.

FLORA LICHTMAN: OK, an animal that pioneers tool use for back scrubbing is really my kind of animal. Tell us what you observed.

MICHAEL WEISS: Since 2018, we’ve been using drones to observe killer whale behavior. But it wasn’t until this last year, 2024, when we got a new drone with a camera with a much bigger Zoom lens on it, that we were able to start seeing this behavior. And what whales were doing is grabbing bull kelp stocks. And if you’ve never seen a bull kelp stock before, what you’ve got to imagine is multiple meters long stem or stipe that’s just basically a big hollow tube that ends in a big gas-filled bulb at the end with these leafy blades coming off.

And if these kelps become detached from the seafloor, they’ll float. And then that thin stipe or stem will dangle in the water. What the whales will do is grab that thin end and break off only about a 2 foot length of kelp stipe.

So it’s this 2 foot length of basically, like, garden hose-like material. They’ll carry that in their teeth to a partner. And right before making it to their partner, they’ll flip that onto their rostrum, onto their nose, and push it against their partner’s side, rubbing it back and forth along each other’s backs anywhere from a minute to– we had one observation that lasted nearly 15 minutes, just rubbing this kelp, rolling this kelp, back and forth across each other’s bodies.

FLORA LICHTMAN: What is your hypothesis? Is this for exfoliation? Why would they do it?

MICHAEL WEISS: Yeah, when we looked at this behavior and when we showed it to some of our colleagues who study other animals like primates, whales with greater amounts of this kind of flaky, sloughing skin on their body were more likely to do this behavior, which kind of hints at that maybe exfoliant function, or maybe it’s just relieving some discomfort that’s associated with having a lot of dead skin. We also found that whales who were closely, maternally related, so mothers and their kids or grandmothers and their grand offspring or maternal siblings, were more likely to do this behavior together and that animals who were close in age were also more likely to do this behavior, both of which also point to that social function that grooming often serves in animal societies.

FLORA LICHTMAN: Yeah, I mean, should we think about this like the chimp grooming that we’ve seen and know about?

MICHAEL WEISS: I think that’s probably a good place to start. I think a big difference with these whales compared to that behavior is that it’s not just one animal grooming another, and then maybe getting something back later in return. Maybe that other animal turns around and grooms them or gives them some food.

It’s two animals who are simultaneously grooming each other. No one’s got hands here. No one’s picking skin off each other. They’re both just using their bodies to rub this kelp back and forth. So it’s a behavior that you need a partner for, but you and your partner are simultaneously benefiting.

FLORA LICHTMAN: Do killer whales in other places do this?

MICHAEL WEISS: Not that we of. We don’t know of any reports of similar behavior in other populations. And actually, we saw this behavior in the southern resident killer whales, which is a closed population of fewer than 80 whales here in the Salish Sea, which are the inland waters of British Columbia and Washington.

What’s interesting is there’s another population of killer whales in these same waters, called the Bigg’s killer whales or the transient killer whales, that we’ve also been observing using the same methods. And despite using the same methods on that population, we’ve never seen them perform this behavior. So right now, all signs are pointing to this being a southern resident killer whale kind of specific social behavior.

FLORA LICHTMAN: Does that mean it’s learned and it’s passed down?

MICHAEL WEISS: That’s our current thought, is that this doesn’t seem like a behavior that would be innate. Most learning that killer whales do is of the social variety, usually from their mothers and grandmothers. We’ve seen very young calves, less than a year old, not necessarily doing this behavior but watching other pairs do this behavior very closely. The mom will be swimming around with a piece of kelp in between bouts of this behavior, and the kid will just be swimming along, staring at that piece of kelp with a lot of interest. So our best guess, really, at this point is that it’s a socially learned behavior, probably learned from mothers and grandmothers.

FLORA LICHTMAN: This community only has 70-some members, right? Does this teach you anything that could help you protect this pod of killer whales?

MICHAEL WEISS: Yeah, I think right now, we don’t know what survival benefits, if any, this behavior gives the whales. What I do think it does, and maybe this is more important, is provides an opportunity for us to reemphasize to the public and to politicians and people making decisions that these are not just 70-some individual whales.

This is, as we were saying earlier, a unique culture and society. There are these sets of behaviors and traditions that if we lose those 73 whales, we’re never getting back on this planet. We’re never going to see it again. And to me, if that’s not worth conserving, I don’t really know why we’re doing conservation. And to me, the culture is one of the primary things we’re trying to preserve.

FLORA LICHTMAN: Have whales ever been observed using tools before?

MICHAEL WEISS: So, other species of dolphin have been observed using tools. Bottlenose dolphins in Shark Bay, Australia, are very well-known for using sponges as foraging tools. They’ll put a sponge on their rostrum while they’re searching through the seafloor kind of as a cushion. Depending on your definition of tools, some folks might call bubble net feeding and humpback whales a form of tool use.

But what’s special here is that these whales are making this tool from an object in the environment that they then have to alter in order to use it for this purpose. The kelp stalks they’re actually finding at the surface would not be usable for this behavior. They’re there too long and unwieldy, and they’ve got these blades that get in the way.

They have to find these stocks and then alter it to just the right length that is then useful for this behavior. So that’s also really rare. We don’t see that in many animals.

FLORA LICHTMAN: You know, I feel our understanding of tool use in the animal kingdom has really changed, even just in the last few decades. Way back, we used to think only humans made tools. Then we had chimps, now sea otters and crows and elephants. Were we thinking about tool use wrong, like it’s not as special or as hard as we thought? Or were we thinking about us wrong, that we’re not as special as we thought?

MICHAEL WEISS: I think when we’re talking about tool use in humans, there is obviously something kind of special there in terms of the complexity of the tools we use and the way we combine them. But I think we are wrong if we think about humans as man, the tool user, which is the classic kind of old school anthropological idea. I also think what this research specifically maybe is showing us is that there’s a lot more tool use even in species that are really well studied that’s still out there in the natural environment to be found.

We’ve been studying southern resident killer whale behavior since the ’70s, every single individual in the population by sight. We know who their family are. We know their social units are.

And yet it took us this kind of leap in our observation abilities that drone technology is provided to see what turns out to be a quite common and widespread behavior in the population. This isn’t one or two individuals doing this every so often. Every indication is that this is every animal in the population doing this behavior daily. And it still took us– it still took us 50 years to find it. So it just makes me think of all the other interesting kinds of tool use that are probably still out there waiting for us to find it.

FLORA LICHTMAN: Thank you. Michael.

MICHAEL WEISS: Yeah, thanks so much for having me.

FLORA LICHTMAN: Dr. Michael Weiss is research director at the Center for whale research in Friday Harbor, Washington. Staying with giants of the deep, researchers have identified 200 new species of giants living in the ocean. And they’re huge, almost as big as a bacterium. These are newly identified giant ocean viruses.

Joining me to discuss is Dr. Mohammad Moniruzzaman. He’s an assistant professor in the Department of marine biology and ecology at the University of Miami in Florida, and he recently wrote about these giant ocean viruses in the journal NPJ Viruses. Monir, welcome to Science Friday.

MOHAMMAD MONIRUZZAMAN: Thank you so much for inviting me, and I’m very excited about talking about this bizarre, we’ll call it, this virus that we study in our lab.

FLORA LICHTMAN: Man, I’m excited to hear you call them bizarre because they sounded bizarre to me. What is a giant virus?

MOHAMMAD MONIRUZZAMAN: So, these are– biologically these are viruses, and they have all the features of a virus. But what sets them apart is actually this really, like, outsized particle size that they are, like, really big. So, sometimes I get–

FLORA LICHTMAN: How big? How big?

MOHAMMAD MONIRUZZAMAN: How big would be– one example I give is that some of these viruses can be as big as a regular bacteria, a 1 to 2 micron in size. Another example I give is that many of these giant viruses have a genome that’s like at least 10 times as big as the coronavirus that we’re still dealing with.

So they’re pretty big. And another feature is that they sometimes have more than 1,000 genes in their genome. A regular virus probably would have 30 to 40 or even like 100 genes in their genomes. But these viruses can routinely have more than 1,000 genes they can encode. Most of these viruses that we know of infect single celled eukaryotic cells in the ocean or freshwater or even, like, soil ecosystems. So basically, they’re infecting eukaryotic microbes.

FLORA LICHTMAN: Do they have different behaviors from an ordinary virus because of all these additional genes or because of their size?

MOHAMMAD MONIRUZZAMAN: We can say yes because when they’re inside the host, when they’re infecting a eukaryotic cell, as they bring in a lot of these genes, many of these genes are actually genes that we see in the cellular life.

So for example, some giant viruses have genes for carbon metabolism or energy metabolism, like Krebs cycle or glycolysis. So some of these viruses will bring these genes in, and they can use those genes to further reprogram the host cell, which actually helps the replication of the virus. So basically, they can use their own genomic material to manipulate host metabolic program.

FLORA LICHTMAN: Wow. So they’re transforming their hosts with this big bag of genes.

MOHAMMAD MONIRUZZAMAN: Yes, I think I would say that. Yes.

FLORA LICHTMAN: And is that what’s in it for them being big, that they have this sort of added power that they can get the cell that they’re infecting to do something new?

MOHAMMAD MONIRUZZAMAN: That’s a big part of the story, that the fact that they have many metabolic genes help them to successfully infect the host and overcome the host defense possibly. Another possible reason could be that many of these viruses likely have a very broad host range. That means they can infect a very large diversity, different types of hosts, different type of eukaryotic cells in the ocean or freshwater.

And having these genes possibly help them with this possible host switching that we call it. Having these genes might help them to adapt to a new host environment. The second hypothesis I just mentioned, it’s not really tested yet, it. So it’s more like my favorite story, like favorite narrative, but it’s not scientifically proven.

FLORA LICHTMAN: Can they infect us?

MOHAMMAD MONIRUZZAMAN: As far as we know so far, there’s– oceanic giant viruses are their close relatives. They don’t infect humans. But we do have some viruses that we know of that can infect other animals like fish.

FLORA LICHTMAN: Where did these giant viruses get all of these extra genes? Did they steal them from some previous host?

MOHAMMAD MONIRUZZAMAN: One of the way they can get it is definitely is they pick up the genes from their host, which is all viruses are known to do that to some degree. But in case of giant viruses, this is very intense. Another way they can gain genes is a process we call gene duplication.

So one gene gets duplicated. So then you have two copies of the same gene. And over time, one of those two copies can actually diverge enough that it becomes a different gene compared to the original gene it duplicated from.

FLORA LICHTMAN: Your team has identified over 200 of these viruses. How did you find them?

MOHAMMAD MONIRUZZAMAN: Obviously, 200 viruses is a lot of them, and we can’t culture them in the lab. What I’m saying is you can actually pick them, isolate them from the ocean, and maintain them in culture in the lab so you can study them. So what we do is we do it indirectly. We have taken metagenomic approach to identify the DNA of these viruses, and we have developed tools to actually separate the viral DNA sequences from everything else in our data set so that we can actually identify those DNA as viral. And that’s how we got to the point where we could actually confidently say that, well, we have 200 distinct viral genomes in this DNA database.

FLORA LICHTMAN: Why do you care about these guys? What’s the bigger picture?

MOHAMMAD MONIRUZZAMAN: Well, so I think from out of pure curiosity-driven research, they’re fascinating. They are very odd in the virus world because of all these features we talked about, the genome size and all kind of metabolic genes that they have which you don’t see in other viruses. I as a scientist, I’m very driven by this question.

Like, why do viruses need to have this many genes? Why do they need to be so big? What is the evolutionary reason that this large size persist in the virus world?

And the second question, of course, there’s this big question of what is their impact. They are incredibly diverse in the ocean, and they’re very common in the ocean. They’re present in the very deep ocean. They’re present in the sunlit, the upper surface.

And that they infect a lot of important primary producers. That’s like algae in the ocean. They also infect things that eat algae, like certain type of planktons.

So they have a very broad impact on the marine food web. And that has impact in the biogeochemical cycle of the planet. And as I always tell my students, always remember, the ocean is big.

It’s actually 3/4 of the world that you live in. And if you scale that up, you can imagine there are billions and billions of giant viruses in the ocean. And the question is, what is their impact on the biogeochemistry of the ocean and the planetary chemical cycles like carbon cycle, nitrogen cycle and things like that. So I am fascinated by this question. That drives me actually to study these guys.

FLORA LICHTMAN: I mean, you found 200. That must be a drop in the bucket.

MOHAMMAD MONIRUZZAMAN: Oh, yeah. Yeah, we’re sure, we’re sure. Actually, 200 is just almost like a beginning.

But the fact is that we have to start somewhere. So this could be a drop in the– what you said, a drop in the bucket or a bucket in the ocean. But it’s still significant as a initial steps.

FLORA LICHTMAN: Fascinating. Thanks, Monir.

MOHAMMAD MONIRUZZAMAN: Thank you so much.

FLORA LICHTMAN: Mohammad “Monir” Moniruzzaman is an assistant professor in the department of marine biology and ecology at the University of Miami in Florida.