Photo: Sepia officinalis. (Schafer & Hill/The Image Bank/Getty Images)
New research into the intelligence of cephalopods, a group of animals that includes squid, octopus and cuttlefish, has shown them to be smarter than we ever imagined. In one test, a cuttlefish has now even passed an intelligence test designed for human children.
The cuttlefish was exposed to what is known as the 'marshmallow test', which involves examining reasoning and delayed gratification. In the human experiment, a marshmallow is placed in front of a child and told that if they don't eat it for 15 minutes, they will get two marshmallows.
Children with higher intelligence and the ability to delay gratification are able to wait the 15 minutes and get a greater overall reward. It also shows the ability to plan into the future.
In the experiment, it was shown that a cuttlefish could be trained to learn that if it didn't eat the food straight away, in this case crab meat, it would gain more food in the future. This shows that cuttlefish are able to think about the future and plan their actions accordingly.
Alexandra Schnell, the researcher who led the project at the University of Cambridge, said of the findings:
"Cuttlefish in the present study were all able to wait for the better reward and tolerated delays for up to 50-130 seconds, which is comparable to what we see in large-brained vertebrates such as chimpanzees, crows and parrots."
Another part of the experiment involved looking at how good cuttlefish were at learning and adapting. In this experiment, the animals were shown two different visual clues, a circle and a square. If the cuttlefish approached the 'correct' one then they would be rewarded with food. When the researchers switched the shape that would result in the cuttlefish being rewarded with food, the animal was able to soon learn that this change had taken place. This means that they have the cognitive ability to understand a changing environment and that the rules of any game can be changed over time.
Researchers are still unsure as to why cuttlefish are able to delay gratification or pre-planning. In most animals that show these behaviours, such as chimps and some types of bird, it is due to the fact they use tools to obtain food and this requires forward thinking and complex planning. As far as we are aware, cuttlefish do not use tools of any kind. It is suspected however, that it may be related to the foraging for food and hunting that the cuttlefish engages in.
"Cuttlefish spend most of their time camouflaging, sitting and waiting, punctuated by brief periods of foraging. They break camouflage when they forage, so they are exposed to every predator in the ocean that wants to eat them. We speculate that delayed gratification may have evolved as a byproduct of this, so the cuttlefish can optimise foraging by waiting to choose better quality food."
The research has now been published in the Proceedings of the Royal Society B.
[h/t: science alert]
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