SWANSEA, Wales — The term “crabby” usually means being particularly irritable or argumentative, but according to a new study, perhaps it should start to be associated with strong navigation and memory skills. Researchers from Swansea University in Wales placed a group of common shore crabs, a species found all over the world, inside a maze. Not only were the crabs able to navigate the maze and find their way out, but they even remembered the route for up to two weeks afterwards.
The experiment was conducted in an effort to better understand spatial learning in crustaceans.
“Learning your way around, what scientists call ‘spatial learning’, is an important ability in animals. We understand this ability quite well in many animals, but less so in marine creatures such as crabs as it’s pretty difficult to follow them around!” comments lead researcher and marine biologist Dr. Ed Pope in a release. “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.”
A total of 12 crabs were tested over the course of four weeks. Each time, food was put at the end of the maze to incentivize the crabs on their journey. The maze’s route was fairly complicated, requiring five changes in direction in order to reach the finish line, and three dead ends.
Over the four-week period, all of the crabs steadily became more efficient in navigating the maze; finishing the task in shorter time periods and making fewer wrong turns.
Additionally, to even the researchers’ surprise, after the crabs were brought back to the maze after two full weeks away from the experiment, all 12 were able to reach the end within eight minutes. This is especially impressive because this time around there wasn’t any food at the end waiting for them. For reference, when the crabs were first introduced to the maze, it took them far longer than eight minutes to find their way out.
According to the research team, this is a clear sign that the crustaceans remembered how to navigate the maze.
“This study is important because we know that insects, especially ants and bees, have some impressive mental abilities but we haven’t really looked for them in their aquatic counterparts. The fact that crabs show a similar ability to insects is, in some ways, not that surprising but it is great to be able to show it so clearly. This work opens the door to more sophisticated experiments looking at how changing ocean conditions might affect crabs’ ability to learn and adapt to find food in future,” Dr. Pope explains.
“We know so much is changing in our oceans due to human caused climate change. Gaining a baseline understanding of the lives of the animals that are going to actually be impacted by the changes in our future oceans is really important. That doesn’t just mean the big charismatic animals, it means things like crabs that are so important for the food chain,” adds co-author Professor Mary Gagen.
The study is published in the scientific journal Biology Letters.