Do you remember what you had for dinner last Thursday? Most likely not. Well, it turns out that cuttlefish can. Scientists have discovered that it is the first animal that shows no signs of deterioration in memory function over time. Your memories remain unchanged.
What makes cuttlefish good subjects for this kind of research is that they only live a couple of years, making it easy to compare memories throughout their lives.
The team experimented with 24 specimens of common cuttlefish (Sepia officinalis ), subjecting them to a foraging training where they learned when and where two types of food were available: grass shrimp (preferred by cuttlefish) and another somewhat less desirable for this cephalopod. They performed memory tests while half of them were between 10 and 12 months old, not quite adults, and the other half were between 22 and 24 months, which is equivalent to humans in their 90s.
After providing the two types of food in two separate places, they began to test the skills of the cuttlefish by offering the least desirable food in one place while the most appetizing food appeared in another place, but only every three hours.
“Cuttlefish can remember what they ate, where and when, and use this to guide their future feeding decisions,” says Alexandra Schnell, from the Department of Psychology at the University of Cambridge, UK, and leader of the study that publishes the journal Proceedings of the Royal Society B. “What is surprising is that they do not lose this ability with age, despite showing other signs of aging such as loss of muscle function and appetite.”
They found that all cuttlefish were able to see what food was on the flag signs and use this information to decide where to go next in search of the prized shrimp.
“The older cuttlefish were as good as the younger ones at the memory task; in fact, many of the older ones did better in the testing phase,” say the authors. “We think this ability could help cuttlefish in the wild to remember who they mated with, so they don’t have the same mate again.”
What makes them so special?
It is possible that the deciding factor is the hippocampus (one of the main structures of the human brain and other mammals), or rather the lack of it, since these cephalopods do not have a hippocampus, while we do.
And it is that, as humans age, they gradually lose the ability to remember experiences that happened at particular times and places; This is what is called episodic memory and its decline is believed to be due to the deterioration of a part of the brain called the hippocampus. Cuttlefish do not have a hippocampus and their brain structure is dramatically different from ours. The vertical lobe of the cuttlefish brain is associated with learning and memory. This does not deteriorate until the last two to three days of the animal’s life, which, according to the researchers, could explain why episodic memory is not affected by age in cuttlefish.
Referencia: “Episodic-like memory is preserved with age in cuttlefish” 17 August 2021, Proceedings of the Royal Society B Biological Sciences.