In nature, there are many animals without eyes. For example: jellyfish, sea urchins, sea cucumbers, etc., but when these animals first appeared on Earth, they did not have the eye as an organ. In addition to these animals, there are some animals that have had eyes in the history of evolution, but over time, they have gradually abandoned the eye as an organ. This article will take stock of ten animals that have given up their eyes in evolution.
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In 2011, while exploring the Cardamom Mountains, zoologist Dr. Enge Sai discovered an animal that resembled a worm, and scientists named it the Dalai Blind Lizard, the scientific name Dibamus dalaiensis, based on the mountain name of the lizard that was found. This lizard has neither eyes nor legs, and looks a lot like a snake.
This lizard spends most of its life digging holes in the soil, for which its eyes and legs are useless and wastes precious energy. So in the long process of evolution, these two organs slowly degenerated. It is worth mentioning that although this lizard looks like a snake, it appears much earlier than the snake.
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In the caves of the Brazilian state of Minas Gerais, there lives a Brazilian blind fish that adapts to the cave environment. The fish was first discovered in the 60s and later rediscovered in the early 2000s. They don't respond to light, they don't have eyes that are visible to the naked eye, and it has evolved to the point where eyes are no longer needed.
Due to the reduction of the local groundwater level, its population is becoming smaller and smaller. Fortunately, due to their eyeless features, they are bred locally as pets, which makes this fish not extinct.
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Kentucky cave shrimp scientific name "Palaemonias ganteri", Kentucky cave shrimp has no eyes, transparent body, body length of about 3 cm. Their food is a variety of organic matter floating in the water, which means they don't need eyes to prey on it. So in the long process of evolution, they gradually eliminated the eye as an organ.
Most of them live in the famous mammoth caves in Kentucky and other underground caves in the region, and the eyeless shrimp is on the verge of extinction due to deteriorating water quality due to groundwater pollution.
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The first samples of the Anguinus cave salamander were discovered in 1689, when it was thought to be the cub of the cave dragon. Unlike the other species on this list, this cave salamander has eyes, but they are underdeveloped and cannot see any light. It uses other senses of smell and hearing to navigate dark environments.
In addition to the eyes, it has many unique features. For example, it is the only amphibian in the world that lives only in water. Their skin is also very rare, and there is not a single bit of pigmentation on it.
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Cave tarantulas are found in several caves in Hawaii. Compared to ordinary tarantulas, they are small in size, with a body length of only about 20 mm. Their above-ground cousins have big eyes, but the Kauai Cave Tarantula has evolved to no longer need them. They are completely harmless to humans.
The spiders are facing the threat of habitat loss as human interventions and activities pollute their habitats. They are currently listed as endangered, and efforts are underway to reduce the loss of their habitat to ensure their survival.
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Catfish without eyes is a catfish found in Texas and is the only member of the genus Satan in the catfish family. The species was originally found in wells, suggesting that it has evolved to live in an underground environment without light. Curiously, it has only been found in five artesian wells so far, and this mysterious species has not been found in the natural environment. There are no visible eyes on the outside of their bodies. They do have remnants of the eyes, suggesting that they once had eyes but evolved to no longer need them.
Compared with the average catfish, the catfish without eyes is relatively small, and can only grow to about 13.7 cm. Crustacean bones were found in their stomachs, meaning they were top predators in their environment. They are currently classified as vulnerable due to groundwater contamination.
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Albino cave crabs have only been found in Agua Cave in Lanzarote, Canary Islands. They were small, all pale and completely blind. From their discovery in 1892 to the present, people still know nothing about them.
Although the name is crabs, they are a type of crayfish (why the name crab has to be asked the person who named them). They have no pigmentation and no kind of eye stems. They do not respond to light and move around through smell, taste and touch. Unlike most species on this list, they are not currently listed as threatened.
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The South Cave Crawfish is found in underground burrows in Alabama and Tennessee and can survive for more than 100 years. One South Cave crayfish is reportedly over 176 years old.
They have no eyes and no reaction to light, feeding on small fish and insects.
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The Mexican lipid carp is a species of lipid carp found in various water bodies in central and eastern Mexico, where populations living in caves do not have any eyes. These fish initially had eyes, like their cousins who lived on the surface of the water, but over time they degenerated their eyes.
A published study showed that "for mexican carp, vision consumes 15 percent of all energy." "To save energy, they degenerate their eyes. To compensate for the lack of vision, they eat whatever they encounter, including rotting plants and animals.
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The Texas hawk salamander is an extremely rare burrowing amphibian found only in Texas. The Texas hawk salamander has no eyes, and it preys on by sensing the movement of the surrounding water.
They are very rare because their range of activities is limited and their numbers have been declining because the groundwater in their areas is contaminated. The International Union for Conservation of Nature (IUCN) has listed them as vulnerable species and conservation efforts are underway to protect their native habitats.