Octopuses Punch Fish That Cheat During Hunts, New Study

In the waters of the Red Sea, fishes and octopuses appear to work together to hunt for tasty treats. However, some fish can get a bit cheeky and attempt to take advantage of the octopus’s efforts, according to a new study. If they do, they might just receive a swift punch from the octopus—a clear reminder that teamwork has its limits.

Octopuses and Fish: Unlikely Hunting Partners in the Red Sea

Typically seen as solitary, clever hunters, octopuses have long puzzled scientists with their advanced behavior despite a lack of social pressures from complex social interactions, says Eduardo Sampaio, a postdoctoral researcher at the University of Lisbon in Portugal and the Max Planck Institute of Animal Behavior. In other words, what drives their intelligence?

Unraveling the Mystery of Octopus Intelligence

A study published in the journal Nature Ecology & Evolution might reshape our understanding of these charismatic cephalopods and their unexpected relationships with fishes.

Sampaio, the lead author of the research, first learned about this behavior at a conference, where a colleague presented videos of day octopuses, also known as big blue octopuses (Octopus cyanea), hunting alongside fish such as goatfish and blacktip groupers. This unconventional partnership sparked a question in his mind: Are these species actually working together as a team?

Sampaio’s 120-Hour Underwater Exploration

To explore this, Sampaio and his team spent 120 hours scuba diving to film the octopuses and conduct field experiments, carefully observing their behavior underwater. After analyzing the footage from both wild observations and controlled experiments, Sampaio concluded that the octopuses and fish were, in fact, cooperating.“ The way we know that it is cooperative is that they both increase their payoffs,” Sampaio explains. 

That means when octopuses and fish hunt together, they both come out ahead—they catch more food or use less energy than if they hunted alone. It’s a win-win situation, showing they’re truly teaming up!

Octopus and Fish Boost Each Other’s Hunting Success

During hunting, octopuses extend their arms and the webbing between them to create a net around hiding prey, a technique known as a web-over. In this cooperative dynamic, the goatfish would first search the area, allowing the octopus to determine whether the group was moving or not. By working with the fish, the octopus could execute a single, targeted strike led by the fish, significantly reducing its hunting effort. “It relies less on speculative hunting and jumping around,” Sampaio notes. “It does one large web-over directly where the fishes are, resulting in much less work and more reward.” The fish benefit by gaining access to prey that would otherwise be unavailable.

Octopus Enforcement: Punching Cheating Fish

However, not everyone in the group contributes equally. One of the study’s most striking findings according to Sampaio is the octopus’s behavior when the group becomes inactive. When the group stops moving, the octopus punches the fish. “It stops punching when the group starts moving, which I found fascinating. This suggests that the octopus understands individuals who are cheating and the dynamics of the group.” 

The blacktip grouper, in particular, often finds itself on the receiving end of the octopus’s punches for not participating. These punches serve as a form of communication, effectively prompting the group into action, says Sampaio.

Fish Signaling and Coordinated Group Movement

The experiments add more support for his theory of collaboration. The scientists found that octopuses would pounce on a structure about 50% of the time, regardless of whether food was present, indicating that their decisions weren’t influenced by odor cues. However, when a fish had previously interacted with the structure, octopuses pounced on it about 90% of the time, suggesting they use social information from other animals, says Sampaio.

They also observed active signaling from fish to octopuses. For instance, in one video, a yellow goatfish repeatedly gestures to recruit the octopus to a specific spot. Further analysis of group movement revealed that the animals don’t move randomly but follow each other in a coordinated way. For example, “anchors” (where one animal stops while others continue) occurred 70% of the time, and “pulls” (where one animal leads others) happened 30% of the time, demonstrating a clear differentiation in movement patterns, says Sampaio. 

Rethinking Octopus Social Behavior

“I was impressed by the depth of data collected and analyzed, which allowed for a more nuanced understanding of this octopus behavior,” says Alex Schnell, marine scientist and octopus expert not involved in the study. “The level of detail revealed subtle patterns and provided insights that highlight the complexity of these interactions.”

For Sampaio, the study highlights the fact that despite being solitary creatures, something in octopus genes allows it to use social information available in the environment and interactions with other species. 

Expert Insights: Complexity of Octopus-Fish Interactions

While the Social Intelligence Hypothesis suggests that an animal’s thinking skills evolve through social interactions, scientists believe octopus intelligence is more likely shaped by predator-prey encounters, such as adapting to different predators and hunting strategies. “With our work we show that it’s a little more complicated than that,”  and that the octopus can have a complex social life with other species.”

Schnell points out that the exact driver behind the animals’ cooperative behavior is still unclear. It might be as simple as animals learning that working together leads to getting food—this kind of associative learning is common across many species, she explains. But it could also involve more advanced thinking, like perspective-taking, where animals consider what their partner is thinking to improve their own outcomes. This type of behavior has been observed in apes and some big-brained birds, like jays, Schnell says. 

“It just goes to show — never judge a book, or in this case, an animal, by its cover,” says Schnell. “As we broaden the spectrum of animals we study, we’re discovering that even the most unlikely creatures display sophisticated behaviors — a reminder of how much more there is to learn.”