It can smell the barn! We've all heard this expression, which suggests that when a horse approaches home, it displays a particular excitement. The study published on Tuesday, September 17 in the journal Frontiers in Marine Science didn't say whether mysids rattle or change their behavior in the vicinity of their caves but one thing is certain: These crustaceans, a kind of tiny shrimp measuring some 5 millimeters, recognize the chemical landscape around them and show a definite preference for the water in their cave. Home sweet home.
It has to be said that caves play an essential role in the lives of these creatures. Prey to a large number of fish and crustaceans, they find the darkness an indispensable protection during the day. But as this same darkness prohibits photosynthesis, there's no way they can unearth the algae, plankton and other plant debris that they delight to feast on. So, every evening, the swarm, made up of millions of tiny individuals, leaves its lair. And in the early morning, satiated, they return to this dark refuge.
Finding the way out of the cave is no problem at all: Just follow the light. Finding the entrance to get back in, however, is far more complex. The calanques in Marseille, where the latest study was carried out, are home to a number of caves which, at first glance, appear quite similar, yet the mysids don't seem to make any mistakes in their daily migration. So how do they find their way?
Thierry Perez's team at Marseille's Endoume marine station, which specializes in the study of this particular underwater cave ecosystem, first realized that, despite appearances, each one hid a particular chemical profile. Systematic analysis of the molecules present in the water revealed hundreds of distinct signals. In the words of the ecologist, this gave each cave a personal signature.
Mysids are no exception. This is the key finding of this research. To establish this, the Marseille researchers set up a simple experiment. Hundreds of individuals were taken from two nearby caves in the calanques, Jarre and Fauconnière. One by one, they were then placed in a Y-shaped device that allowed them to choose between two waters: Theirs, the one from which they had been extracted, and another. And the result was obvious: While the visibly curious crustaceans tested both arms of the device, they spent far more time in the one that housed their native environment. Their way of choosing. The researchers carried out the same experiment with Leptomysis, small shrimps living, once again, in the creeks, but outside the caves. This time, no preference was observed.
You have 31.66% of this article left to read. The rest is for subscribers only.