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Can Crabs Think? Can Lobsters Feel?

Denyse O'Leary
Photo credit: Luis Miguel Bugallo Sánchez, CC BY-SA 3.0 , via Wikimedia Commons.

Because crustaceans have shells, we may tend to think of them as like machines. Yet crustaceans, along with octopuses, show some surprising abilities and complexities. Take crabs,for example:

A new Swansea University study has revealed how common shore crabs can navigate their way around a complex maze and can even remember the route in order to find food …

Spatial learning is quite complicated, so figuring out how it works in crustaceans gives us a better understanding of how widespread this ability, and learning in general, is in the animal kingdom.”

The researchers tested 12 crabs over four weeks, placing food at the end of the maze each time. The route to the end of the maze required five changes in direction, and included three dead ends.

Over the four-week period, the team saw the crabs show a steady improvement in both the time taken to find the food at the end of the maze and, crucially, in the number of wrong turns taken.

Even more surprisingly, when returned to the maze two weeks later but without any food on offer at the end, they all reached the end of the maze in under eight minutes — a clear sign that they had remembered the route.

New crabs which had had not been in the maze before took far longer to reach the end, and some did not make it to the end of the maze at all during the one-hour study period. 

SWANSEA UNIVERSITY, “CRABS CAN SOLVE AND REMEMBER THEIR WAY AROUND A MAZE” AT SCIENCE DAILY (OCTOBER 22, 2019) THE PAPER IS OPEN ACCESS.

Another thing about crabs is that they suffer from stress. Noise from ships rattles shore crabs:

… when crabs were subjected to a simulated shore bird attack, those that heard ship noise didn’t run and hide as they would normally. “About half of the crabs exposed to ship noise did not respond to the attack at all, and the ones that did were slow to hide themselves,” says Carter. “Similar to how people have trouble concentrating when stressed, the nature of their response indicates that they couldn’t process what was happening, as if that awareness and decision-making ability just wasn’t there.”

CELL PRESS, “SHIP NOISE LEAVES CRABS TOO STRESSED TO HIDE FROM DANGER” AT SCIENCE DAILY (MARCH 9, 2020) THE PAPER IS OPEN ACCESS.

So some calculation is going on inside that shell, if only in the interests of finding the menu or not becoming the menu. But calculation goes on inside a computer too and we don’t think of the computer as a “being,” in any sense.

What about shrimp? Their brains turn out to have memory and learning centers, which has triggered an evolution squabble.

Read the rest at Mind Matters News, published by Discovery Institute’s Walter Bradley Center for Natural and Artificial Intelligence.

Denyse O'Leary

Denyse O'Leary is a freelance journalist based in Victoria, Canada. Specializing in faith and science issues, she has published two books on the topic: Faith@Science and By Design or by Chance? She has written for publications such as The Toronto Star, The Globe & Mail, and Canadian Living. She is co-author, with neuroscientist Mario Beauregard, of The Spiritual Brain: A Neuroscientist'€™s Case for the Existence of the Soul. She received her degree in honors English language and literature.

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crabscrustaceansevolutionlearninglobstersmemoryoctopusesshipsshrimpstressSwansea University