In an intriguing Ecuadorian cave, a cave fish species has evolved to something that might just do it: orienting navigates through their denticles, teeth-like structures but that emerge from the skin.
The use of these sensory structures appears to be an evolutionary phenomenon not known so far, and can only exist in this cave.
So the researchers believe, the Pontifical Catholic University of Ecuador, University of Maryland at College Park, United States, and the U.S. National Institutes of Health, who have discovered the existence of this fascinating evolutionary oddity, an extraordinary adaptation to living in an environment steeped in darkness and in the waters circulating at high speed.
Many fish have denticles. Calling them is not quite teeth unfortunate in regard to its composition, since they have dentin and enamel layers of teeth, the teeth themselves, and the mouth. The common use of denticles in fish is to make cuts, protect, or reduce drag through the water when swimming.
The Astroblepus pholeter, the fish that live in this cave Ecuadorian developed a new way to use them: a form of sensory perception of their environment. The team of Daphne Soares, University of Maryland, found that the denticles of these fish are over becoming tools to perceive their environment, which create images that allow hydrodynamic bearings in a dark environment with fast flowing water.
Generally, fish perceive the flow of water through neuromasts, small organs in their lateral line that share characteristics of the human ear. Most cave fish neuromasts system has expanded to better adapt to life in the darkness, but the Astroblepus pholeter of almost no use of anything in this animal. Instead, their denticles are connected to the brain mechanosensory, allowing the fish to detect the water flow direction and the distance from the bottom as its denticles deviate currents, judging by the findings from the study.
The discovery reveals a new way in which evolution has allowed an animal species living in this challenging environment. Not only is completely dark, but that the world surrounding these fish flows very quickly.
Soares believes the rapid water flow and turbulent lives of the cavern where the Astroblepus pholeter may be the reason that their denticles have evolved this way. The prevailing currents are probably too strong that the system neuromasts were able to develop as it did in other species. And gives the example of trying to listen to someone speaking in a rock concert: For a normal person, the background noise is too high.