It seems octopuses might be the unlikely Muhammed Alis of the marine world. Biologists have filmed combative cephalopods throwing haymakers at fish who join them on cooperative hunting expeditions.
Though largely solitary animals, octopuses often team up with schools of fish to hunt prey such as molluscs and crustaceans. A team from the Max Planck Institute of Animal Behaviour in Germany observed such behaviour, filming 13 hunting groups consisting of octopus and several different species of fish (including goldfish, gold-saddle goatfish and blacktip groupers), in the Red Sea off the coast of Israel.
They found that the different species in these ‘hunting parties’ took on different roles. For instance, goatfish acted as scouts, deciding where the group patrolled, while the octopuses led the charge when it was time to attack.
This joint approach led to the groups catching more prey than if they hunted alone. However, it was far from happy families. Sometimes when a fish was brave enough to get between the octopus and its dinner it was met with a stiff jab worthy of any boxing ring.
The punches serve to push the fish to the outer edges of the group where they are less likely to catch the prey, or to exclude them from the group entirely, the researchers say. Fish were also observed ramming each other out of the way, but at no point did a fish ram an octopus.
“It turns out that the punching is directed to fish that try to exploit the octopus and the group, particularly the blacktip grouper species,” the study’s lead author Dr Eduardo Sampaio told BBC Science Focus.
“Moreover, we found that punching is also associated with the group's movement. That is, if the group is too clustered around the octopus and doesn’t move through the habitat, the octopus punches fish in order to show this negative feedback.
"When the group is moving, the octopus doesn’t punch the fish, as there are prey opportunities being created for all members of the group.”
The researchers now plan to further study the role that each different species plays in the group and to further investigate their means of communication.
About our expert
Dr Eduardo Sampaio studies the behaviour, cognition and neural functioning of cephalopods at Germany's Max Planck Institute of Animal Behavior.
Read more: