Thesea starsthey have aboutprimitive eyes on the tips of his armsthat allow them to visually track their environment, according to new research led by marine biologist Anders Garm, from the University of Copenhagen (Denmark). These eyes, capable of forming images, could constitute an essential stage in the evolution of vision in the animal world.
To test its operation, the researchers placed starfish with and without eyes on sandy bottoms one meter away from coral reefs, where if they did not move they could starve. By monitoring their behavior, they found that onlystarfish with intact eyes drifted towards the direction of the coral, while those starfish that lacked eyes walked randomly.
“The results show thatthe nervous system of starfish must be able to process visual information“emphasizes Dr. Garm. In the analysis of the morphology of the photoreceptors in the eyes of starfish, the researchers also confirmed that they constitute an intermediate state between the two large known groups of photoreceptors, rhabdomeric and ciliary, both with microvilli and a modified cilium.
The best-known starfish species have a compound eye at the tip of each arm, which largely resembles the compound eye of arthropods. Despite being known for nearly two centuries, a visual behavior of this organ has never been documented before, according to the authors of the study at the annual meeting of the Society for Experimental Biology held in Valencia.
