“Reel them in,” marine ecologist Dr. Mike Heithaus says with a laugh. No, Shark Week titles don’t get much grabbier than his, Sharks vs. Dolphins: Face Off, which premieres tonight at 10 p.m. on Discovery. As it suggests, the two species are at odds more than we suspect, and the hour looks at not only likely attack scenarios — see one in the sneak peek above — but also the strengths and weaknesses of each.
You’ve been studying this relationship for 20 years. What is it that fascinates you?
Dr. Mike Heithaus: I’m just, in general, really interested by interactions between predators and prey, and what that means for the health of ecosystems. If you think about sharks and dolphins, these are two of the top predators in the ocean. How do they navigate that relationship, and how does that interaction between the two affect the rest of the ocean ecosystem? It’s kind of like when you think about lions and hyenas: they’re two top predators. What happens when you have a conflict between those two?
What do you think will surprise people most?
I think people are usually just surprised by the fact that sharks can get dolphins, because the story that people had usually heard is that dolphins will beat up and chase the sharks. When I started working with this question, that’s what I thought. People would actually say, “Why are you bothering to study this? Dolphins are too smart to get eaten by sharks.” I think people are surprised that this happens at all. But to me, the other interesting thing is that the impact that sharks have on dolphins isn’t just if they eat them. If the dolphins really change their behavior in order to stay safe — they will avoid areas, the buffet table of awesome food, if it’s dangerous there — that means some of the prey of the dolphins are actually protected by the presence of sharks in some of these areas. I think that that’s a cool thing.
Then the final one is, people really don’t think that sharks get eaten by dolphins. There are some dolphins that will eat sharks. The bottlenose dolphin, they’ll kill small sharks. They’ll actually, in some areas, kills porpoises, just use them as play things. Killer whales are the biggest dolphins — in some populations, killer whales actually specialize in eating sharks. In New Zealand, killer whales will specialize on eating rays and sharks. Then there’s this group of killer whales they call the “offshore whales” that are in the Pacific Northwest, off British Columbia and Washington state, that appear to dive down to deep depths and eat sleeper sharks a lot.
The special shows a dolphin named JoJo in Turks and Caicos that goes after nurse sharks.
I have never had the opportunity to meet JoJo myself. But you would not want to be in your shark costume if you met JoJo.
What’s the most memorable interaction you’ve seen between dolphins and sharks?
One of the most interesting things I ever saw was when I was working in Western Australia. This was really early in my career. We ran into a small great white shark. We were excited, but we were really calm, like, “Oh, we finally see a shark.” We just started following it and watching it, and we noticed it turn. It started heading right toward a group of dolphins that were hanging at the surface.
My colleague and I were pretty much freaking out: “Oh my gosh, this shark’s going to go attack the dolphins.” The dolphins were faced right toward the shark. The shark kept swimming to them, and the dolphins didn’t even notice it was there until it was probably within about eight feet or less of them. Then one of them must have seen it and just panicked. All the dolphins shoot underwater, and this is a group of moms and calves, and they came up leaping. It was every dolphin for themselves including calves. I think they leapt for five minutes away from this area, and the shark never attacked. It was probably as freaked out as the dolphins when they scattered. That was one of those inklings. It was kind of a small white shark. The adult dolphins weren’t too much smaller than it. If you’re ever going to have a situation where it should be “defend and beat up the shark,” it would seem that that would have been it. The fact that that didn’t happen just goes to show that the best defense is No. 1, not to run into a shark, but No. 2, swim away very quickly.
Another thing that intrigued me, when I was studying the dolphin with my colleague Richard Connor at the University of Massachusetts, is male dolphins have social relationships among them that look a lot like politics to us. Your friend today may be your enemy tomorrow. They’ll team up to attack other ones. The two of us would be in different boats. We would see these dolphins would be together, they’d break apart, go their separate ways, maybe be a mile or more apart from one another. We’re listening underwater for sounds, and won’t hear anything that would be communication, and those dolphins will come together and basically coordinate some attack, like attacking another dolphin, or engaging in one of these social relationships. How did they coordinate? It almost seems like they’re able to plan what’s going on. They’re on the same page. I think that the level of communication and social complexity in dolphins is really amazing.
As you mentioned, we all know how smart dolphins are. But I was surprised to see in the special that one was able to look at two poster boards covered with different quantities of large dots and, 85 percent of the time, correctly pick which board had the smaller number. And also, if you cover one dolphin’s eyes, it can still mimic what the dolphin next to it is doing, in terms of spinning or jumping.
The sensory abilities of dolphins are incredible. Even their echolocation, the clicks they send out so they can see with sound, they can eavesdrop on other dolphins. If one isn’t making clicks, but another does, and the echo bounces off, they can kind of eavesdrop on that click. I guess that’s one of the reasons that people get surprised that sharks can attack dolphins. They seem like they’re super smart, they’ve got these sensory abilities, but there’s still a chink in the armor, which is that echolocation only goes out in front of the dolphin. There’s plenty of sound in the ocean to mask the water movement of the sharks. Sharks still can sneak up on dolphins. So they’ve got to be careful in areas where there are big sharks that could be dangerous.
And why is it important for the ecosystem to continue studying where these attacks are most prevalent and whether the dolphins are leaving those areas?
It’s partially because dolphins eat so much fish. They’re warm-blooded, so they have to eat a lot more than sharks do. If you change where the dolphins are, or how they’re feeding, it could affect the fish, and then that could affect the coral reefs or the sea grass. There’s the potential for these effects to cascade through the whole ecosystem.
Sharks vs. Dolphins: Face Off premieres June 29 at 10 p.m., after Deadliest Shark, which explores whether the oceanic white tip deserves that title, at 9 p.m., on Discovery.