An in-depth look at cuttlefish hunting
The tricky part was getting them to wear glasses.
Yes, this is a cuttlefish wearing 3D glasses.
The reason is that it was one of a group of cephalopods invited to a special underwater theatre in Massachusetts, US, and encouraged to strike out at images of two walking shrimp.
And the reason for that is that scientists led by the University of Minnesota wanted to better understand how cuttlefish determine the best distance to strike moving prey.
The images were offset, allowing the researchers to determine if their subjects were comparing images between the left and the right eyes to gather information about distance to their prey. This process is called stereopsis, and it is the way humans determine depth.
"How the cuttlefish reacted to the disparities clearly establishes that cuttlefish use stereopsis when hunting," says Trevor Wardill, lead author of a paper in the journal Science Advances.
"When only one eye could see the shrimp, meaning stereopsis was not possible, the animals took longer to position themselves correctly. When both eyes could see the shrimp, meaning they utilised stereopsis, it allowed cuttlefish to make faster decisions when attacking. This can make all the difference in catching a meal."
The findings are significant, the researchers say, because they provide further evidence that complex brain computations such as stereopsis are not exclusive to higher order vertebrates.
"This study takes us a step further toward understanding how different nervous systems have evolved to tackle the same problem," says first author Rachael Feord.
"The next step is to dissect the brain circuits required for the computation of stereopsis in cuttlefish with the aim of understanding how this might be different to what happens in our brains."