Having the ability to see the world around us is a crucial feature that helps us survive. The same goes for the animal world. However, there are some species that do not have an organ of sight, at least not in the classical sense, and yet they are able to see.
How is this possible? Creatures that live underwater adapted to the conditions that rule far below the surface. In greater depths, where there is little or no light at all, some animals have developed rather special abilities. Due to recent advancements in genome sequencing, scientists have been able to determine what cells are actually helping the animals to see when they do not have eyes. These are called light-sensitive cells. There are some other exciting solutions other species have found.
The way in which the sea urchins adapted to low-light conditions is nothing short of amazing. The ends of sea urchin's feet are covered in light-reactive proteins, which technically transform the whole bottom of the animal in one big eye. Sea urchins change their colors if there is any light stimulus nearby.
Hydras are closely related to jellyfish, although much smaller. They have no problem maneuvering the sea depths without eyes. This is thanks to their tentacles, which contain the light-sensing proteins at their very top.
This species is specific only to the Mammoth Cave area located in Kentucky. These shrimp species are now endangered, due to the pollution of the waters around the world, and the fact that they are autochthonic to only one ara. They live in quite dark circumstances, but they have adapted so they can see with the help of other senses.
These blind residents of caves in Missouri are liking their life in the dark. They never leave the dark areas, so they do not have eyes and have become completely translucent.
This species is still puzzling the scientists, as it has been discovered relatively late. A creature that lives in the Amazon river looks like a snake but is more similar to a salamander. Not only does this animal live without eyes, but it also has no lungs either!
The olm is a type of salamander that lives in caves across Europe. Having a very long lifespan of around 100 years, this species uses other senses to move around the caves. The olm's senses are so sharp it can even detect electricity.
Albino Cave Crab
This animal actually belongs to the lobster family, despite the name it got. Living only in the caves found on the Canary Islands, this albino crab is blind. It is small and pale, but it gets around just fine the caves of Jameos del Agua in the city of Lanzarote.
This fish species is also blind. Well, at least most of them are because it sometimes happens that individual specimens are born with eyes. Without eyes, the Mexican Tetra maneuvers the pitch-black surroundings by sensing the changes in water pressure.