Credit: Discovery Channel

Loyal Shark Week viewers have, in years past, seen reef sharks turn upside down and go near catatonic. It’s a state known as “tonic immobility,” and while the sharks appear to enjoy it, it also renders them unable to defend themselves. In the new special Zombie Sharks (premiering Aug. 13 at 9 p.m. ET on Discovery), professional diver Eli Martinez sets out to determine whether great whites can, like their reef brethren, also achieve tonic. If so, it could help support one theory about a recent spike in orca attacks on white sharks: killer whales may have learned how to induce the state. Since there’s nothing not interesting about the idea of zombie sharks, we talked with Martinez about the phenomenon and his show.

EW: Shark Week fans know how bold Andy Casagrande is. He was the only cameraman willing to go to New Zealand with you as you tried to test tonic on great whites. If Andy calls you a little crazy, wow.

MARTINEZ: We’re both in the same field, we just specialize in different things. He spends a lot more time shooting some of the craziest footage you’ll ever find, and my thing is trying to play with the sharks as much as I can.

Why is tonic so fascinating to you?

Why do sharks have this adaptation in their natural state? What’s the main purpose of it? No one really knows. There’s definitely some kind of high they get from it. To see that you can induce this on a wild animal, and that the wild animal would enjoy it—you see them go lethargic, almost falling asleep in your hands—there’s no greater feeling. What’s exciting is whether other animals are exploiting this. Obviously, an animal like an orca being able to induce tonic in sharks so it can eat them—that’s exciting. I mean, that’s not something I want to see—I love sharks a lot—but if I’m there, and I’m witnessing it, man, what a treat.

After you learn to do it on reef sharks, you test it on a tiger shark. How difficult was that to master?

The first time it ever happened was by accident. I put my hand on a tiger shark’s face so I could feel her and know where she’s at—I’m able to push her away from me if she gets too excited or shows any signs of aggression. Then it kind of evolved into just rubbing their face every time they come in. Then one day I did something and the tiger shark just started spinning in my hand. I had no idea what I did, and it kinda freaked me out. But at the same time, it was really cool. A little while later it happened again. I was trying to figure out why it was rolling, spinning and turning and exposing its belly to me, which is when they’re the most vulnerable. It was after countless dives that I was able to figure it out and induce it at least once on every dive. It went from me being able to roll them to having them go vertical. It was always something they allowed me to do. It was nothing that I was forcing. If I force it, they don’t want to play. You can feel it: As soon as they come in, and I start giving them a little nose rub or a little belly rub, I can feel them relaxing and allowing the interaction to happen.

At one point you’re in a cage, looking for a great white to try this on, and we see the shark “mark its territory” around you, as the narrator puts it. I don’t recall seeing that before. Is that rare?

I don’t know if it was marking its territory or just telling me what he thought of me. He swam underneath the boat, stopped, and came back and did it again. That was a first for me. It was special, I guess. [Laughs]

So you eventually find a curious great white, and you’re trying to touch its nose off the side of the boat. Then you go back in the water in a cage—and then you get out of the cage. It didn’t seem like Andy was expecting that.

You can try to plan things, but you can’t really do anything until you’re actually in the water and feeling out the animals that are there, because every shark has its own personality. You just have to play with it and say, “Now’s the right time, or it’s not.”

You’re outside the cage trying to work with one shark—then a larger one arrives and you have to swim to the cage. How alarming was that moment?

It’s not the sharks that you see that you have to worry about, it’s the sharks you don’t see. You have to remember they will exploit opportunities. It’s a matter of respect, and knowing what you’re doing and when you’re doing it. With white sharks, that’s what it’s all about—looking for the right opportunities, and hoping that you’re gonna follow the rules. If you break the rules, you will pay the price.

This was your first time with great whites in New Zealand. What did you learn?

The sharks in New Zealand are really, really big. The visibility is not always the greatest. Conditions are cold, so you have thick wetsuits, which minimizes your movement. I work a lot with sharks in the Bahamas, the tigers. I’m able to move around. So everything’s different. It boils down to time in the water, and making sure you do everything right. First and foremost, white sharks are extremely shy. They don’t really like people, so they tend to shy away from you. I know they’re big and scary looking, but they get that big by being extremely careful. So it’s hard to get a great white to want to come up to you. Then finding out the personality of that animal once he does come in. I’m looking for one that’s not darting in and out, going extremely fast. That’s the hardest part of the whole thing, finding the right shark. You need one that’s gonna work with you, so that you and it will be able to feed off each other … or, rather, vibe off each other. “Feed,” I guess, is a bad word for this. [Laughs]

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