Memory of explicit occasions doesn’t fall apart with age in cuttlefish

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• Source: University of Cambridge


• Date: 19 Aug,2021

Researchers have discovered that Cuttlefish can recall the exact details of specific events, even up to the end of their lives. These results were published in the journal Proceedings of the Royal Society and are the first to show that animals can retain specific events even after they age.

Memory tests were conducted by researchers from the University of Cambridge (UK), the Marine Biological Laboratory, Woods Hole, Mass. and the University of Caen (France) with common cuttlefish, Sepia officinalis. Half were between 10-12 months and half were between 22-24 months and two-thirds were between 20-24 months of age – the equivalent of humans in their 90s.

“Cuttlefish are able to remember what they ate and where it was. This information can be used to help them make better food choices in the future.” It’s amazing that they retain this ability even though they show other signs of ageing like loss of muscle function or appetite,” stated Alexandra Schnell, first author from the University of Cambridge’s Department of Psychology. She conducted the experiments at MBL Senior Scientist Roger Hanlon.

As we age, our ability to recall events that occurred at specific times and places gradually declines. For example, last Tuesday’s dinner. This is known as episodic memory and is caused by the decline of a portion of the brain called the the hippocampus.

Cuttlefish don’t have a brain with a hippocampus and their brain structure differs from ours. Learning and memory are linked to the cuttlefish’s brain’s vertical lobe. Researchers believe this is why episodic-like memory in cuttlefish does not decline over the course of their lives.

The cuttlefish had to be trained to move in a certain area of their tank that was marked with a white and black flag. They were then taught that grass shrimp (which they love) and king Prawn were two of the foods they could eat. This was done after they had experienced specific delays and were able to access specific flag-marked areas. For four weeks, this training was repeated each day.

The cuttlefishes were then tested for their recall of what food was available and where it was. The two feeding spots were different each day to ensure they didn’t learn a pattern. Every cuttlefish, regardless of age, watched the food that first appeared at each flag to determine which feeding location was the best for each meal.

The old cuttlefish were just as good as the younger ones in the memory task – in fact, many of the older ones did better in the test phase. We speculate that this ability might help cuttlefish in the wild to remember who they mated with, so they don’t go back to the same partner; such behaviors might promote gene spreading throughout the regional population.”

Alexandra Schnell, First Author

Hanlon said, “We have been studying cuttlefish extensively in field and laboratory for many decades, but these sophisticated behavior are a surprise to even us.” Many more discoveries are still to be made about the relationship between brain and behavior.

Cuttlefish live a short life span, with most living to around two years. This makes them an excellent subject for testing whether memory declines as we age. It is difficult to determine whether animals can remember things. The authors used the term “episodic like memory” to describe the cuttlefish’s ability to recall what, where, and when they happened.