How do octopuses and fish carry out "cross-border hunting cooperation"?

In nature, we often see animals of the same species cooperating to achieve a certain goal, such as wolves hunting together or bees building hives together. However, cooperation between different species is relatively rare.

Recently, a study published in the journal Nature Ecology & Evolution unveiled the mystery of octopuses and fish hunting together. This cross-species friendship is more complex and wonderful than we imagined.

Octopus and fish hunt together

Cross-border cooperative hunting is more efficient

When you think of cross-species cooperation, you probably first think of the deep friendship between humans and dogs. Whether it's herding or hunting, humans and dogs always work together to achieve their goals. But similar cooperation also exists in the underwater world.

Moray eels and groupers are a classic cross-border hunting partner. When a grouper approaches a moray eel and sends a hunting signal, the moray eel will respond immediately, and a wonderful hunting drama begins. The grouper will indicate the crevices of the coral reef where the prey may hide, while the moray eel is good at driving the prey out of the coral. The two work together seamlessly, leaving the prey nowhere to hide.

Compared with hunting alone, the success rate of cross-border cooperation between moray eels and groupers has greatly increased. But new questions also arise: Who is the real leader in cross-border cooperation between species? Do both parties reach a consensus through some form of compromise, or does one species dominate the decision-making?

To answer these questions that have long puzzled scientists, biologist Eduardo Sampaio of the Max Planck Institute for Animal Behavior in Germany and his international team conducted an in-depth study of cross-species interactions between the big blue octopus, which is usually considered to be solitary, and a variety of fish, such as goatfish and grouper.

Octopus or fish, who decides to hunt?

Octopuses and fish share a common goal - to improve hunting efficiency. In the past, it was believed that octopuses were the leaders of the hunting team, and fish just followed closely behind to pick up leftovers. When hunting, octopuses use their long tentacles to explore every corner of the hunting grounds, drive out prey, and then fish can take advantage of the opportunity to catch them. In this scenario, octopuses are the absolute decision makers, and fish are just followers.

However, when researchers looked deeper, they found that the cooperative relationship between octopuses and fish was far more complicated than they had imagined . Without detailed analysis and solid evidence, it is difficult to reveal the true mystery of this cooperation.

Blue goatfish plays a role in exploring the environment and finding prey

In order to understand the details of the cooperation between octopuses and fish, researchers dived in a coral reef near the coast of Eilat, Israel for about a month, tracked 13 octopuses with several cameras, and recorded 120 hours of 3D video data. During this period, the researchers tracked 13 predations of the octopus and observed that each octopus had 2 to 10 fish groups working with it.

Through the video footage shot during diving, the Sampaio team conducted an in-depth behavioral analysis. They found that in the cross-border cooperation between octopuses and fish, each partner plays a specific role. In fact, there is no single leader in the cooperation, but a "democratic consultation" model has been formed.

Video data showed that blue goatfish would wander around and lead the hunting group in a certain direction, but if the octopus did not immediately follow, the group would linger. Sampaio explained that the blue goatfish played the role of exploring the environment and finding prey, while the octopus was the decision maker of the group's actions.

Do octopuses and fish share prey when they cooperate? Researchers have not found evidence of this, but as long as members of the group can catch the prey, they can enjoy a good meal.

Octopus and blue goatfish hunt together, but blackfin grouper waits on the sidelines

Fish is lazy, octopus punishes with a whip

Although octopuses are generally more successful at catching prey when they forage with fish companions, not all members of the group are as dedicated as they should be.

The research team observed that blackfin groupers often "slack off", sticking to the group but not participating in hunting. At this time, the octopus will stretch out its tentacles to hit them, as if punishing or driving away these "free-riding" members. This behavior not only maintains the efficiency of the team, but also reveals that the octopus has complex cognitive abilities - they can recognize the contributions of collaborators and take action to maintain order.

Is this social hunting behavior of octopuses an innate skill or something they learn? The researchers speculate that it may be something they learn, because small octopuses seem to have a harder time cooperating with fish than large octopuses.

In summary, this study proves that octopuses have amazing sociality and decision-making abilities, overturning people's stereotypes of them as "solitary and less social". In addition, the "democratic model" of cross-species cooperation also provides a new perspective for understanding animal cognition: even if the evolutionary paths are completely different (octopuses are invertebrates and fish are vertebrates), organisms can still achieve win-win results through division of labor and negotiation.

Reference Information:

[1]https://phys.org/news/2024-09-octopuses-fish-decisions-complex.html

[2]https://www.nbcnews.com/science/science-news/octopuses-hunt-with-fish-punch-video-rcna171705

Compiled by: Wen Xing

Planning: Liu Ying, Zhang Chao, Li Peiyuan, Yang Liu

Reviewed by: Zhang Jinshuo, Director and Researcher of the National Museum of Zoology