September 24, 2024, 10:29 am | Read time: 4 minutes
Octopuses are considered solitary animals. However, for the first time, video recordings from a new study show that the animals hunt together with different species of fish. They even deal blows to fish that do not participate in the hunt. PETBOOK has summarized the exciting results.
Biologists long believed that octopuses were solitary creatures, coming together only for mating purposes. However, a new study suggests that some of them maintain a surprising amount of social contact – with fish. This is particularly true for individuals of the big blue octopus (Octopus canea). Using underwater images, researchers showed for the first time that these octopuses hunt in groups with different species of fish. The octopuses appear to decide how and what is hunted. The results were published in the scientific journal Nature on September 23. 1
Diving expedition reveals hunting secrets
Eduardo Sampiano and his colleagues wanted to study the hunting behavior of octopuses during their dives. The researchers went out into the seas of Israel, Egypt, and Australia and recorded over a hundred hours of footage. However, instead of encountering solitary hunters, they observed that some individuals of the big blue octopus hunted together with various fish. This is a previously unknown behavior.
In total, they followed the octopuses on 13 hunts. During these, they observed groups of two to ten fish working with each octopus. Two cameras were used simultaneously for the filming, which allowed the researchers to later create a 3D view of the scenes.
Each fish has its task
The hunting groups usually consisted of one octopus and several species of reef fish, such as groupers and mullets. The influence that each individual had on the hunt was not evenly distributed. Rather, they are hierarchical structures, as biologist and study leader Eduardo Sampaio explains in the scientific journal PhysOrg.
This means that each fish has a specific task. For example, mullets are primarily responsible for exploring the environment and setting the direction of the group. On the other hand, the octopus determines the timing and initiation of the group’s movement when hunting. However, they take on less of a leader’s role. Rather, they lead the hunt and ensure that it is regulated and that social order is maintained.
Stragglers receive a tentacle slap
If fish danced out of line, the octopus would hit them with its tentacle. In particular, those fish that only took advantage of the group, i.e., did not move while hunting or looking for prey were hit, as Sampaio reports in an article in the US news magazine NBC News.
However, the strikes were not only used to keep group members in check, but also to keep the group moving. “When the group is very still, and all the fish are swimming around the octopus, it starts to strike,” explains the biologist. “But if the group is moving along the habitat, that means it’s looking for prey, so the octopus is happy and doesn’t hit anyone.”
Fish and octopuses have advantages by hunting together
The researchers believe the fish benefit from such hunting groups because an octopus can reach into crevices where prey is hiding. This allows it to reach food sources that are otherwise denied to the fish. The octopus benefits from the hunting group by following the fish to the food instead of searching for food itself.
“This cooperation allows fish to reach otherwise inaccessible prey and octopuses to conserve energy by focusing on high-value food sources while exerting control and providing feedback within the group, highlighting the sophisticated dynamics of marine life cooperation,” summarizes Sampaio.
Prey is not shared directly
But how do octopuses and fish regulate who gets how much of the prey? “When the octopus catches the prey, it also kills it,” explains Sampaio. The prey is not directly shared but consumed by the individual who captures it. However, as the group repeats the hunt several times, the prey is “shared” in the sense that sometimes the octopus catches the prey, and sometimes the fish catches the prey, as the biologist explains.
The research results show that the otherwise solitary big blue octopus exhibits remarkable social competence and cognitive flexibility, adapting its behavior in response to the actions of different species. “These results expand our understanding of leadership and sociality and emphasize the complexity and adaptability of social interactions in nature,” says Sampaio.
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Octopuses are more similar to us than we think
The researchers’ video recordings are the world’s first evidence that at least one octopus species exhibits traits and markers of intelligence that scientists have previously only attributed to vertebrates.
“I think that sociality, or at least attention to social information, is much more deeply rooted in the evolutionary tree than we may think,” says Sampaio. “We are very similar to these animals,” he adds. “In terms of sentience, they are very close or closer to us than we think.”