Nature’s Exceptional Eyeless Animals

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The eyes may be the windows of the soul, but for a fascinating array of species, the eyes just don’t have it. Today, we discover bizarre creatures that have jettisoned their eyes through means like atrophy in the course of evolution. A rule of nature: if it’s not useful, drop it! The eyes are either missing or grossly atrophied in these strange creatures adapted to their dark worlds.

10. Blind Cave Crayfish

Imagine a lobster in the form of a ghost and you will have a realistic image of the blind cave crayfish species. The animals known as crayfish in North America are close relatives of marine lobsters and bear a very similar appearance to lobsters often encountered in the ocean and sometimes on a dinner plate. When crayfish adapt to subterranean aquatic ecosystems, they turn into pale white, ghostly apparitions, no longer needing to invest any energy in maintaining pigment or vision.

August 16, 1999 saw the discovery of yet another species of blind crayfish in Ozark County: ghostly pale and adapted to cave life that was not yet described by science. The dark, muddy, flooded cave from which the new species was hauled is in a protected area, kept confidential to protect the new species. Other, better known species of blind cave crayfish such as Cambarus cryptodytes provide insight into the ecology of these animals. Feeding on small prey, such as blind cave salamanders, as well as scavenging waste and feeding on small invertebrates are among the ways these animals find food. In the case of Cambarus cryptodyteswhich measures two inches long, oversized antennae twice the length of the crayfish make it easy to find food despite a lack of light and vision.

9. Blind Deep Sea Lobster

Just like a cave, the deep sea hides creatures away in darkness, far from the reaches of the sun. And here in the depths we find the Blind Deep Sea Lobster. It is a fairly new species discovery from a depth of 984 feet in the Philippine Sea. Not only is it blind, the pale creature has horror movie-worthy barb-studded claws of incredible length that more than make up for its lack of eyes as it seizes food. While regular lobster species have traditional claws, one thicker for crushing and one thinner for slicing, the Blind Deep Sea Lobster has claws that are out of proportion to each other, one being far longer than the other.

The longer claw is so out of scale that it is nearly the length of the lobster’s entire body. Not only are the lobster’s two claws formidable pincers, they are studded with terrifying “teeth” all the way from front to back. Prey has little chance to escape. The species was discovered during an expedition of the Census of Marine Life and subsequently given the scientific name Dinochelus ausubeli in honor of Jesse Ausubel, who co-founded the Census of Marine Life. The pinkish and white shaded creature’s ghostly appearance is made far creepier by its obvious lack of eyes.

8. Texas Blind Salamander

Looking like a ghost with gills, the Texas blind salamander navigates effectively in its limited underwater environment, a system of caves that are full of water from the Edwards Aquifer in Hays County, Texas. The water bodies in which the salamanders exist may be dark, but the water quality is extremely high. The lack of pigment produces the pale white coloration, while the extended gills allow breathing underwater during the adult phase, long past the larval stage of development.

Growing up to 5.5 inches long, the Texas Blind Salamander is reasonably sized, while the level of atrophy seen in the eyes of this species is extraordinary. Instead of eyes, the creature has only two tiny spots that are under the skin, thanks to evolutionary regression. As the salamander makes its way in the darkened environment, food is sometimes scarce but, when encountered, highly nutritious. Despite a lack of eyes, prey also stands little chance once detected. The blind salamanders can tell when an unlucky shrimp, snail, or insect affects the surrounding water pressure, tracking movement and making a catch. Reproduction is no problem either. Females will even make passes at eligible males, including nipping them to garner their interest.

7. Mexican Tetra

Also known as the blind cavefish, the Mexican tetra (Astyanax mexicanus) looks like a normal, attractive little fish in its shape, albeit a bizarre version without functional eyes. While the blind cavefish morph of Mexican tetra is most freakish, it is worth noting that it is not a separate species, but rather just a morph (or variant) of the Mexican tetra, a pretty typical small fish species. The eyes of blind morph Mexican tetras are covered over with skin and pale white or beige in appearance patrols certain cave waters for food in a bizarre case of change within a population of a species.

The Mexican tetra is actually a distant relative of the notorious piranhas of the Amazon and is also genetically linked to the ever popular aquarium fish, the neon tetra. Despite being among the most exotic and bizarre aquatic creatures known, Mexican tetras are becoming more familiar over time due to their rising popularity as ornamental fish. Specimens can be found in local fish stores as an unusual choice for the home aquarium. Juveniles have some light sensing ability, but as eyes would be a useless draw on energy, other adaptions take priority, such as the fish’s ability to navigate via water pressure fluctuation sensing. Experiments show that the blind cavefish form can successfully spawn with the surface dwelling fish of its species, with fertile offspring resulting.

6. Speleonectes: Eyeless, Fanged Crustaceans

Lava tubes may be extreme environments that are the exotic remains of past volcanic activity and, sometimes, remain as sites of current volcanic events. In some lava tubes, strange, eyeless crustaceans are found making a living in their dark, undersea environment. In the pitch black of a submerged cave of volcanic origin off the Canary Islands, two species of Speleonectis (the name meaning “cave swimmer”) are found. Here in the pitch black darkness, these crustaceans — distant relatives of lobsters, crabs and shrimp — do not see their prey but nevertheless find them and then inject venom through their fearsome fangs.

The cave in which both the original species and the second Speleonectis species were discovered is called “Tunel de la Atlántida,” which translates to “tunnel to Atlantis.” Speleonectes atlantida, the scientific name of the new species (which is more physically active than the original Speleonectes species found) is “Cave Swimmer of Atlantis” in English. The discovery was published in Marine Biodiversity. DNA testing was used to confirm the variation between the two species of Speleonectes.


5. Blind Spider

Spiders are scary enough, but how about underground spiders without eyes? Well, German scientist Peter Jäger had the distinct experience of discovering a large eyeless huntsman spider hidden in a cave in the Southeast Asian country of Laos in 2012. There are 1,100 species of huntsman spider roaming the world, and the discovery of the cave loving Sinopoda scurion is significant given that the species is the only eyeless huntsman spider species known to science.

Jäger, who is the arachnology (science of spider biology) head at the Frankfurt-based Senckenberg Research Institute, discovered the spooky pale spider 60 miles from the enormous Xe Bang Fai river cave. Spiders normally have exceptional vision for an invertebrate with eight distinct eyes, but in the case of Sinopoda scurion evolution has led to the regression and gradual disappearance of sight organs, leaving the spiders attuned to picking up movement of prey, yet sightless.

4. Cryptotora thamicola

A blind fish is interesting enough, but how much more fascinating is a ghostly white blind fish species that climbs up waterfalls and recalls a reptile or amphibian, so good is its locomotion capabilities? A novelty that caught researcher attention, Cryptotora thamicola was discovered in Thailand making use of exceedingly shallow rushing waters in complete darkness of partially flooded caves. The fish may not have eyes, but they hold superpowers as far as fish are concerned.

Equipped with “superfins,” Cryptotora thamicola not only moves through shallow water, less than half an inch deep, but can even haul itself up small waterfalls as it travels throughout subterranean environs. Researcher Brooke Flammang, a New Jersey Institute of Technology Federated Department of Biological Sciences assistant professor, became the lead author of a study covering the physiology of the extremophile fish, even putting together 3D models showing their unusual locomotion methods. The hip structure of this species is very unusual, consisting of strong pelvic bones and supporting connections that hold the backbone sections together. This allows extreme strength similar to a tetrapod; definitely not a fish.

3. Blind Scorpions

Scorpions are scary enough, but how much more freakish would it be to see a scorpion but know it does not see you? Blind, eyeless scorpions are a thing, with Mexico being host to a fascinating set of such species. Because blind animals live in dark and out of the way places, many have been out of the view of researchers and are comparatively new to science, only discovered in recent years. Typhlochactus is the sole scorpion genus to be completely lacking eyes. In 1968, Typhlochactus sylvestris was discovered in a montane (meaning high elevation forest) region in Mexico, where it hides and hunts in the darkened environment provided by thick leaf litter.

The scorpion may lack eyes, but it dispensing with eyes allows development to be focused on other adaptations more useful to a denizen of the dark, such as increased sensitivity to nearby prey items and agility in navigating the leaf litter. Three other species of eyeless scorpions are known, but these are blind for a different reason, being inhabitants of dark caves where they opportunistically seek out their prey.

2. Martialis heureka

Ants may seem commonplace, but it is a bizarre ant species that captivated famed biologist Edward O. Wilson, a scientist known for popularizing awareness of the importance of biological diversity in natural systems. Martialis heureka is a blind ant species from a region of Brazil’s Amazon rainforest, close to Manaus. The ant is so strange, lacking eyes and being fully adapted for a dark environment lifestyle, that Wilson and a fellow researcher stated that the creature should be from Mars. This feedback is reflected in the generic name Martialis, which is a new genus, of which this species is the sole member. The species’ name heureka refers to the unexpected nature of its scientific discovery.

The lack of eyes indicates that the ants are likely users of exceedingly dark environments, such as hollow cavities in rotting tree roots and under thick leaf litter. Interestingly, the lack of eyes is paired with another most unique adaptation. Long mandibles that cross over like forceps are present, a trait not seen in any other species of ant. These appear able to assist in hauling prey items out of dark crevices.

1. Florida Worm Lizard

Lizards are not just green, four-legged creatures that crawl around tree branches, rocks, and gardens. There is an array of blind lizard species. There are many species that slither, snake-like through sand, soil, and other dark subsurface environments, sensing their prey through non-visual means. Looking somewhat like a section of corrugated hose bleached white and then come alive, the strange and sightless Florida Worm Lizard takes creepy to a whole new level.

Rhineura floridana lacks external ear openings and grows about 7 to 11 inches in length. The life of this animal is a subterranean one, crawling through the ground in complete darkness, preferably in sandy soil. In such conditions, eye and ear openings would be a handicap rather than a help to the animal. Worm lizards are not considered snakes, but a resemblance is obvious given these reptile’s lack of legs. They are not true lizards, either, but constitute their own reptilian group called amphisbaenids, with characteristic genetic and physical oddities. When flooding happens, the ghostly reptiles may appear on people’s lawns or driveways, forced out of their secretive lairs by the water.


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