I’ve got a lovely bunch of coconuts’ shells

Octopuses using coconut shells has been all over the web the last couple of days due to the publication today of a new paper by Finn and colleagues. The title is helping generate the attention: tool use.

This is a cool finding, but it is not as path-breaking as one might think.

First, the authors do note that there have been possible cases of tool use in invertebrates besides octopuses, but argue that other cases are too context-specific to be “real” tool use.

Second, this is not the first time the phrase “tool use” has been used regarding octopus behaviour. I remember having discussions about tool use in octopuses arising from discussions with Jennifer Mather, my undergrad supervisor. In her field site, she noted that octopuses made dens. These were not just nooks and crannies that octopuses crawled into. The octopuses actively modified their dens by bringing in rocks to block the entrance.

So we’ve known for 15 years that octopuses can actively use objects in their environment for protective purposes. I think the coconut shell carrying and use could be an extension of the den modifying behaviour. The difference with coconuts is that the octopuses can move them around with them, and it’s hard to think of rocks an octopus could do that to.

The coconut carrying behaviour is interesting not because it shows tool use as such, but because it shows anticipation and planning. They show octopuses carrying the coconut shells under their bodies. Finn and company argue that is costly behaviour, except that the octopus could then cover itself with the two halves of the coconut.

In reading the paper, though, I am not sure if they saw a case where an octopus carrying the coconut shells switched to covering itself with the coconut shell. Yes, I’m being picky with that criticism. They may have seen that behaviour. Even if they did not see it, it’s a completely reasonable assumption that the octopuses do use the shells as shelter, and I have no other hypothesis as to what the octopuses are doing with those shells. But if they did not see it, it’s important to keep in mind that they’re inferring the connection between carrying the coconut shells and using them as shelter.

References

Finn, Julian K., Tregenza, Tom, & Norman, Mark D. (2009). Defensive tool use in a coconut-carrying octopus Current Biology, 19 (23), 1069-1070. DOI: 10.1016/j.cub.2009.10.052

Mather, J. (1994). ‘Home’ choice and modification by juvenile Octopus vulgaris (Mollusca: Cephalopoda): specialized intelligence and tool use? Journal of Zoology, 233 (3), 359-368 DOI: 10.1111/j.1469-7998.1994.tb05270.x