For the first time, scientists have documented how lionfish use their pointed, venomous fins to hunt prey together.
“Cooperation requires high cognition, but fish have traditionally been perceived as being at the bottom” of the cognition scale, said the study‘s lead author, Oona Lonnstedt, a graduate student in marine biology at James Cook University in Queensland, Australia. “But when you look at their social behaviors, you can see that these fish are way more advanced than we thought.”
Lionfish are actually a group of several related species that were historically found in the Indian and Pacific Oceans. With striped bodies and an array of venomous fins, they’ve become prized in the aquarium trade. (See “Top 5 Myths About Lionfish.”)
They’re also known as consummate predators, with few natural enemies. To make up for their lack of speed, lionfish use specialized swim bladders to move about the water column and catch their prey.
These hunts were thought to be solo endeavors. But Lonnstedt spent thousands of hours watching lionfish, both in the lab and in the wild. And she noticed that some of them appeared to be working together to catch other fish.
“The lionfish were in large groups, and they were moving their fins around like fishermen with nets,” she said. “It made me really curious about this behavior.”
If You’re Hunting and You Know It, Wave Your Fins
One thing soon became clear: In each case the fin fanning directly preceded several lionfish hunting for prey. Lonnstedt hypothesized that it was an example of cooperative behavior that allowed the fish to hunt more successfully.
To test her theory, Lonnstedt and colleagues at James Cook University built a special tank that held prey fish at one end. They placed a Dendrochirus zebra lionfish in the middle of the tank, letting it explore the area and discover the prey fish. Then they placed a different species of lionfish (Pterois antennata) at the opposite end of the tank from the prey fish.
Sure enough, Lonnstedt saw the same behavior in the tank as she had in the wild: D. zebra approached the other lionfish and waved one fin after another, then swam back over toward the prey. If the other fish failed to follow, D. zebra returned to it and repeated its fin display.
The approach paid off. Hunting together, the two species of lionfish were 50 percent more successful at catching prey than fish that hunted on their own.
Serena Hackerott, a marine biology graduate student at the University of North Carolina in Chapel Hill, says these studies could potentially help conservationists develop strategies against another species of lionfish—Pterois volitans—that’s been causing tremendous damage to native reefs in the Caribbean and the Atlantic seaboard.
“It’s a really interesting study that could help us learn how lionfish hunt,” Hackerott said. “Determining whether the invasive lionfish hunt like this will be an important next step.” (Related: “Pictures: Sharks Taught to Hunt Alien Lionfish.”)