Octopuses have been caught on film punching fish out of spite, according to scientists who recorded the footage.
Researchers from the University of Lisbon in Portugal said the ‘punching’ took place during hunts when the octopuses and fish were hunting alongside one-another.
Biologist Eduardo Sampaio said in some cases the ‘punches’ appeared to be motivated by practical gain, such as stealing prey off a fish.
But in several cases, the punches appeared to be administered to ‘impose a cost’ on ‘misbehaving’ fish – an emotion that researchers compared to ‘spite’ in humans.
This is the moment an octopus (pictured) randomly punches a fish ‘out of spite’ while hunting alongside them
The octopus can be seen moving towards the fish and hitting them out of the way with its tentacle. Pictured: the octopus just before its attack
In the footage, octopuses can be seen moving towards the fish and hitting them out of the way with its tentacle.
The two species often hunt together and use each other’s hunting strategy to their advantage but it is rare to see an octopus punch a fish.
While this bizarre behaviour is sometimes out of spite, it can also be to keep its hunting companions in line as competition grows fierce, researchers claim. Any misbehaving fish trying to steal prey may also take a hit.
‘Octopuses and fishes are known to hunt together, taking advantage of the other’s morphology and hunting strategy,’ explained marine biologist Eduardo Sampaio, a co-author of the study published in the Ecology Journal.
‘Since multiple partners join, this creates a complex network where investment and pay-off can be unbalanced, giving rise to partner control mechanisms.’
He continued: ‘We found different contexts where these punches occur, including situations where immediate benefits are attainable, but most interestingly in other contexts where they are not.’
The team of researchers, led by Mr Sampaio, from the Marine & Environmental Sciences Centre of the University of Lisbon in Portugal, filmed the octopuses off the coast of El Qusier, Egypt and Eilat, Israel between 2018 and 2019.
An octopus (centre) approaches a fish before punching it with its tentacle
The different octopuses engaged in ‘active displacement’ of their partner fish in the Red Sea during collaborative hunting. For the octopus, punching serves as a partner control mechanism.
‘To this end, the octopus performs a swift, explosive motion with one arm directed at a specific fish partner, which we refer to as punching,’ the researchers said.
The team recorded punches targeting different fish species, from tailspot squirrelfish, blacktip and lyretail groupers to yellow-saddle.
‘These multiple observations involving different octopuses in different locations suggest that punching serves a concrete purpose in interspecific interactions,’ the researchers added.
While this bizarre behaviour is sometimes out of spite, it can also be to keep its hunting companions in line as competition grows fierce, researchers claim. Any misbehaving fish trying to steal prey may also take a hit
They hypothesise that the punching is used to control the other fish during hunts – either to move them away from prey or to evict them from the group completely.
In cases where fish are opportunists and try to reap the benefits of the hunt without contributing, the octopus can punch the fish due to simple competition, the researchers claimed.
But on two occasions, an octopus punched a fish for the purpose of retrieving prey.
‘In these cases, two different theoretical scenarios are possible. In the first one, benefits are disregarded entirely by the octopus, and punching is a spiteful behaviour, used to impose a cost on the fish,’ the researchers said.
They also think the punching may just be a ‘form of aggression’ against a misbehaving fish.
The team are conducting further research to understand why this bizarre behaviour occurs.