Texas blind salamander (Eurycea rathbuni)
For my second species, we are going to venture far from the mountain tops of the Rockies and descend into yet another remote and unforgiving landscape. You may recognize these little guys from the BBC Planet Earth episode on caves, but the Texas blind salamander is so much more than meets the eye.
This salamander wasn’t discovered until the 1890s when it was seen in a flowing artesian well at the San Marcos National Fishery, which we now know as Texas State University. The Texas blind salamander only rarely come up to the Earth’s surface and when they do, they make sure not to stay there long, so had they arrived a minute later, the U.S. Fish Commission (the precursor to the U.S. Fish and Wildlife [USFWS]) may have missed this inconspicuous animal. The Texas blind salamander is considered by herpetologists to be one of the most specialized cave-adapted salamanders in the world, yet it is endemic only to the water-filled caves fed by the Edwards Aquifer near San Marcos in southcentral Texas.
Deep in the caverns of southcentral Texas, the Texas blind salamander resides with transparent skin, skinny delicate little legs, and red feathery external gills. The gills are outside its body for acquisition of as much oxygen as possible from the low-light, oxygen-deficient water of the caverns. This other-worldly translucent body is only 3-5 inches in length and half of that length is just in their tail alone. And get this, that 3-5 inch long pallid creature is the top predator of its Texas habitat. Who knew this little amphibian could be the baddest thing in part of southcentral Texas? Not only are they very small for being a top predator, but they also hunt without vision. Texas blind salamanders have eyes but they are under the skin and look more like basal eye spots in juvenile years. Because they live in caves, their eyes have evolved to be completely dysfunctional. As they age, the eye spots disappear and it becomes hard to tell if they ever had eye spots at all. So you might ask, how does this salamander hunt then? From a human’s point of view, they just look like they are perched on the ledge of the cave walls waving their heads from side to side, but in reality, they are actually sensing where their prey is. The Texas blind salamander has tiny receptors all over its skin that detect minute movements of its microscopic prey. These receptors work by sensing waves in the water that are created by the prey which produce changes in water pressure. A small change in water pressure signals to the salamander that something it wants to eat is moving, which works well in the still underground waters. The salamander’s diet usually consists of tiny snails, blind cave shrimp, and various other aquatic cave invertebrates. In feeding on these small organisms, this top predator acts as a keystone species for the other species living in this cave ecosystem, which includes over 40 endemic plants and animals! But, interestingly enough, it doesn’t encounter these species often. It is believed that in the 180-mile-long cave system the salamander can go months without confronting any food at all.
It is believed that the Texas blind salamander is able to reproduce all year round, which is a rare occurrence in mother nature. But, like their prey, an encounter with a mate or another salamander at all is likely to be infrequent. A recent study found that females may be in charge of initiating reproduction as they showed a preference to associate with males over females, whereas, the males showed no preference. The scientists concluded that most likely mating solely relies on the females’ chemical cues to select males or avoid females.
Up next we will discuss the environmental issues that the Texas blind salamander faces: The Texas blind salamander: Tales of an irreplaceable water snob living in Texas — The Environmental Issue
If you would like to check out more animals on the Endangered Species List on your own, please visit the U.S. Fish and Wildlife Service’s list of Threaten/Endangered Species in the U.S. and Foreign Countries.
References: Connally, K. Conservation Plan Keeps Edwards Aquifer Full of Life. U.S. Fish and Wildlife Service, [Online] Apr 2013 https://www.fws.gov/endangered/map/ESA_success_stories/TX/TX_story2/index.html (accessed Mar 6, 2017). Edwards Aquifer Authority. Drop Inside The Edwards Aquifer, Edwards Aquifer Authority, [Online] Jul 2011 https://www.youtube.com/watch?v=NzYWOM2TmJk (accessed Mar 6, 2017). Hammerson, G.; Chippindale, P. Eurycea rathbuni. The IUCN Red List of Threatened Species, [Online] 2004 http://dx.doi.org/10.2305/IUCN.UK.2004.RLTS.T39262A10173274.en (accessed Mar 6, 2017). Epp, K J.; Gonzales, J.; Gabor, C. R. The role of water-borne chemical cues in mediating social interactions of the Texas blind salamander, Eurycea rathbuni. Amphibia-Reptilia. [Online] 2010, 31, 294-298 DOI:https://doi.org/10.1163/156853810791069065 (accessed Mar 6, 2017) National Wildlife Federation. Texas Blind Salamander. National Wildlife Federation, [Online] 2017 http://www.nwf.org/Wildlife/Wildlife-Library/Amphibians-Reptiles-and-Fish/Texas-Blind-Salamander.aspx (accessed Mar 6, 2017). Texas Parks and Wildlife. Texas Blind Salamander (Eurycea rathbuni), Texas Parks and Wildlife, [Online] 2017 http://tpwd.texas.gov/huntwild/wild/species/blindsal/ (accessed Mar 6, 2017). Images: Image 1: Impurestcheese. Issue #33: Olm. http://whitleyaward.org/wp-content/uploads/2010/12/Jana-Species_Proteus.jpg (accessed Mar 6, 2017). Image 2: Hooks, C. Amphibious Assault. http://www.texasmonthly.com/wp-content/uploads/2017/01/reporter-amphibious-assault.jpg (accessed Mar 6, 2017). Image 3: National Aquarium. Animal Updates - June 21. http://aqua.org/~/media/BlogImport/20130619105837jpg.jpg (accessed Mar 6, 2017). Image 4: Bedek, J. Transparent Snail, Zospeum tholussum, Discovered in Croatia. http://i.huffpost.com/gen/1355898/images/o-TRANSPARENT-SNAIL-facebook.jpg (accessed Mar 6, 2017). Image 5: Forsyth, A. 9 Unearthly Subterranean Creatures. http://topiik.com/wp-content/uploads/2016/10/Blind-Salamanders-from-Texas-1024x768.jpg (accessed Mar 6, 2017).