Ageing cuttlefish can still remember last week’s dinner, say University of Cambridge researchers
Can you remember what you had for dinner last Wednesday?
If not, you could blame the area of your brain known as the hippocampus, which deals with your episodic memory, but is believed to deteriorate as we grow older.
Scientists have discovered that cuttlefish have no such issues - right up to the last few days of their life, they can remember what, where and when things happened.
The findings, published today (Wednesday) in the journal Proceedings of the Royal Society B, are said to be the first evidence of an animal with a memory of specific events that does not deteriorate with age.
“Cuttlefish can remember what they ate, where and when, and use this to guide their feeding decisions in the future,” said Dr Alexandra Schnell in the University of Cambridge’s Department of Psychology, first author of the paper. “What’s surprising is that they don’t lose this ability with age, despite showing other signs of ageing like loss of muscle function and appetite.”
Cambridge researchers teamed up with the Marine Biological Laboratory in Woods Hole, Massachusetts, and the University of Caen, to conduct memory tests on 24 common cuttlefish (Sepia officinalis), half of which were were just below adult age at 10-12 months old, while others were 22-24 months, equivalent to humans in their 90s.
They were tested using two foods - king prawns, of which they’re not big fans, and live grass shrimp, their preferred choice. Flags were waved in their tank at the sites where these foods were provided, at three-hour intervals. The locations were changed daily, and this was done for four weeks.
All the cuttlefish watched which food first appeared at each flag and worked out which feeding spot was best at each subsequent flag-waving.
“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 think this ability might help cuttlefish in the wild to remember who they mated with, so they don’t go back to the same partner,” said Dr Schnell.
Cuttlefish only breed at the end of their life, but it is important they remember who they mated with, where, and how long ago so they can spread their genes widely by mating with as many partners as possible.
Cuttlefish have a dramatically different brain structure to humans and do not have a hippocampus. Instead, the ‘vertical lobe’ of the cuttlefish brain is associated with learning and memory and does not deteriorate until the last two to three days of the animal’s life.
The research was funded by the Royal Society and the Grass Foundation.