According to a new study, cuttlefish may recall events up to their last few days of life.
The study is considered to be the first to show that an animal’s recollection of specific experiences does not degrade with age.
Memory tests were performed on 24 common cuttlefish. Half of them were between the ages of 10 and 12 months (thus not quite adults) and the other half were between the ages of 22 and 24 months (equivalent to a human in their 90s).
- The fish were taught to approach a black and white flagged spot in their aquarium.
- They were educated that specific flag-marked sites offered two of their favorite dishes.
- The flag was flown at one place, and they were offered a piece of king prawn, a dish they dislike.
- For four weeks, they were given live grass shrimp from a new location with a different flag every three hours. They prefer grass shrimp a lot more.
- To ensure that the fish weren’t learning a pattern, the two feeding places were changed every day.
- When a flag was waved, the cephalopods watched to see which food appeared first, so they could figure out which feeding spot was best.
The researchers were interested in seeing how well the cuttlefish remembered which meal was offered.
The findings showed that, although human episodic memory (remembering events from different times and locations) declines with age, cuttlefish memory does not.
This is thought to be due to the hippocampus, which is present in human brains but absent in cuttlefish brains.
The vertical lobe of the brain is associated with learning and memory in cuttlefish, and it does not degrade until the last few days of life.
“Cuttlefish can remember what they ate, where they ate it, and when they ate it, and use that information to influence their feeding decisions in the future,” said first author Dr. Alexandra Schnell of the University of Cambridge’s department of psychology.
“What’s remarkable is that they don’t lose this capacity as they get older, despite other indicators of aging like muscle loss and appetite reduction.”
“In the memory task, the older cuttlefish were just as excellent as the younger ones – in fact, several of the older ones did better in the test phase,” Dr. Schnell added.
“We believe that this capacity may aid cuttlefish in the wild in remembering who they mated with so that they do not mate with the same partner again.”
Researchers from the University of Cambridge, the Marine Biological Laboratory in Woods Hole, Massachusetts, and the University of Caen in France collaborated on the project.
It’s in the Proceedings Of The Royal Society B: Biological Sciences journal.
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