A video showing Japanese pygmy squid splatting their prey with ink before attacking it casts doubt on existing theories about how cephalopods use their ink. Rather than squirting it as a defensive mechanism to help them escape predators, the footage suggests that it could also form part of their offensive weaponry.
Numerous species have previously been observed using ink to evade threats, although a new study in the journal Marine Biology is the first to document this type of predatory behavior. To conduct the study, researchers placed Japanese pygmy squid in tanks with three different species of shrimp, and observed their mode of attack.
A total of 322 predation events were recorded, with the squids using ink as an aide on 13 of these occasions. Interestingly, the way in which ink was deployed was not always the same, and its effectiveness as a predatory tool varied depending on which species was being hunted.
In their report, the study authors describe how ink was utilized in two different ways, either by creating a “smokescreen” in between the squid and its prey, which it then burst through in order to attack, or by squirting away from their prey in order to distract it and then attack from a different angle.
Of the 13 occasions in which the squid used ink, they produced a single squirt 11 times and three squirts twice. The success of these attacks was 75 percent when hunting a type of shrimp called Latreutes acicularis, and only 11 percent when hunting a different species called Palaemon serrifer. Interestingly, the squid were not observed using ink to attack a third species of shrimp, Neomysis intermedia, although precisely why this is remains unclear.
Even more intriguing is the fact that success rates were no higher when ink was used compared to when it was not, leaving researchers scratching their heads as to why the animals bother with this type of predatory behavior.