“Bêtes de science” is like a collection of stories. Beautiful stories that tell the living in all its freshness. But also in all its complexity. A parenthesis to marvel at the treasures of the world. For this new episode, let’s take the path to the seaside to discover a funny fish: the jumping goby.
The goby is a funny. A fish that likes to stretch its fins … out of the water! To breathe, it then draws oxygen from the mouthfuls of water that it has previously compressed in its gills. But it also takes advantage of what scientists call skin breathing. Yes yes, you understood correctly, he breathes with his skin. Because as long as it stays wet, it can directly absorb oxygen from the atmosphere.
So the goby has developed strategies for breathing. But how does he get around? Without being able to swim … Well, imagine that this strange fish has simply learned to walk! To drag himself, rather. By relying on its pectoral fins. They are lower than in other fish. More muscular too. He can thus wiggle in the mud of the mangrove where he likes to hunt. At the cost of significant effort, all the same.
But that’s not all. The goby is also able to climb vertical surfaces. Thanks to his pelvic fins this time. Merged into one, they form a sort of suction cup. Enough to allow our funnyto stick to trees and rocks to find their favorite prey. Small crustaceans, worms or even all kinds of .
A formidable spatial memory
And if the goby is nicknamed the jumping fish, it is because it has also developed this ability. So no, don’t imagine him as a merry manleaping. It is in a light and fast that the goby arches its body to eject itself from the surface of the water. This technique is useful for him to escape attacks from birds, for example. Because the goby also likes to live by the ocean. So when the drops, it may find itself “trapped” in the pockets of water formed by the rocks. While waiting for the and to escape its predators that have fallen from the sky, it has learned to jump from cavity to cavity.
A risky strategy? Not when you have the elephant memory of the jumping goby. To avoid ending up parched on a rock, the little fish registers the surrounding relief. While swimming, he spots all the potential refuges that the rocks will form once the water is withdrawn. Then, at low tide, when in a cavity, he knows exactly which direction to jump to reach the neighboring cavity. All while counting on ajust a few milligrams. This strategy was observed by scientists as early as the 1950s. They even evaluated the accuracy of jumping gobies in the . Small fish reach their goal 97% of the time. It’s not nothing.
Perhaps more surprisingly, the researchers were able to show that the goby’s memory is maintained over the long term. At least over 40 days! And that he is able, ceaselessly, to memorize new environments, new reliefs. Aincredible spatial. Lined with a sort of memory of the tide, then. Since the goby must also remember the heights of water. However, memory is an essential component of . And yes, imagine with no memory, we should start from scratch every morning and relearn everything. It is impossible, in such circumstances, to hope for real progress. So … not so stupid, the jumping goby!