Happy World Turtle Day! Turtles Can Learn From Each Other

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Admittedly I don’t know much about turtles. So when I found out today is World Turtle Day, it was the perfect opportunity for me to dig around for some interesting research on these aquatic creatures.

A few years ago, two scientists from the University of Tennessee, Knoxville did a clever experiment and discovered that one type of turtle, the Florida Red-bellied Cooter (Pseudemys nelsoni), can learn from each other.

A Florida Red-bellied Cooter. Source: iNaturalist.
A person holding a Florida Red-bellied Cooter to show its size. Source: iNaturalist.

The scientists came up with the idea because not a whole lot is known about whether turtles are social or not–you can sometimes see them basking in the sun together and they get together to mate, but do they actually “hang out” together? The scientists saw some behaviour in a group of turtles that looked like they were behaving socially. They also witnessed turtles copying one turtle who tried to get a yummy leaf that was hanging over the surface of the water. Maybe turtles are more social than we think? The second observation in particular led to the question: Can turtles learn from each other?

In their laboratory, the scientists had six Florida Red-bellied Cooters. These turtles had hatched in their lab and lived in captivity in a big tank of water. The scientists set up a tank where at one end there were two bottles sitting above the water surface on bricks. One bottle was white and the other was black. Under one of the bottles was a food pellet. The scientists trained two of the six turtles how to knock one of the bottles over to get the food pellet: for one turtle, the pellet was always under the white bottle, and for the other turtle, the pellet was always under the black bottle. Interestingly, one turtle always knocked the correct bottle over by swiping at it with its front legs, whereas the other turtle knocked the bottle over by biting at it. (The scientists swapped the positions of the bottles every so often so that the turtles had to learn the colour of the correct bottle, rather than its position.)

The set-up the scientists used in their experiment. On the left you can see the top of the white bottle and the top of the black bottle. Underneath one of the bottles is a food pellet, and the turtle had to learn which colour bottle to knock over to get it. Here a turtle is climbing up toward the black bottle. It has paint on its shell so the scientists could tell the turtles apart. Source: Journal of Comparative Psychology.

Soon the two turtles learned to knock over the correct bottle to get the food. These turtles were called the Demonstrators. The scientists then put the remaining four turtles, one at a time, with one of the Demonstrators, so they could watch as the Demonstrator knocked over a bottle to get the food pellet. These four turtles were referred to as the Observers. Then the scientists placed each Observer alone with the bottles to see what they would do. Did they learn how to get a food pellet simply by watching a Demonstrator?

When tested on their own, all four Observer turtles chose the correct bottle: if their Demonstrator had to knock over the black bottle, the Observer chose the black bottle; if their Demonstrator had to knock over the white bottle, the Observer chose white. But the funny thing is that the Observers simply approached the correct colour of bottle or just touched it with its snout. They did not attempt to knock over the bottle, like their Demonstrator had done. I wonder why? The scientists aren’t sure either. Maybe the Demonstrator turtles’ big shell blocked the view of the Observers so they couldn’t see exactly what the Demonstrator did to knock over the bottle? More research could perhaps provide an answer.

The cool thing is that turtles learned from other turtles which bottle to choose. And I think it’s neat that the Demonstrators had their own way of knocking over the bottles. This research scratches the surface of what is going on in those reptilian brains. What else is waiting to be discovered? Maybe turtles have more of a “social life” than we think.

Two Florida Red-bellied Cooters. I wonder if they are communicating with each other somehow? Source: iNaturalist.

Reference

Davis, K. M., & Burghardt, G. M. (2011). Turtles (Pseudemys nelsoni) learn about visual cues indicating food from experienced turtles. Journal of Comparative Psychology, 125(4), 404-410. DOI: 10.1037/a0024784