Natural Selection and Eurycea Rathbuni, Research Paper Example

Salamanders are a family of amphibious creatures that inhabit a wide variety of habitats around the world.  These creatures are small and are normally hunters, eating small insects, fish and other small invertebrates.

Various species of salamanders in Texas inhabit areas close to springs, lakes and rivers since, being amphibious; they must be near water to survive.  In Central Texas, many creeks and springs are seasonal.  They flow during the rainy season but can remain dry most other times of the year.   Since salamanders must be near water, some species have found unique ways to adapt to the environment.

Eurycea rathbuni is a small salamander that has found a way to thrive underground.  At some point in the distant path, this species was a ground dweller.  As water become scarce on the surface, the Texas Blind Salamander discovered that there was plenty of water year round underground in the Edwards Aquifer.  The aquifer is a series of limestone caves that holds water from the rainy season year round.  Eurycea rathbuni found plenty to eat down here, including shrimp, snails and other aquatic invertebrates.  When Eurycea rathbuni first entered the underworld, the species had eyes.  However, as it is eternally dark in the aquifer, his eyes were useless.  Instead of using eyes to hunt, Eurycea rathbuni by “sensing pressure waves created by the creatures it was hunting.” (TPWD)

Since the eyes were useless, over time they became less and less of an important trait to pass on to offspring.  The eye organs atrophied and the salamander became “blind.”  Since this trait was no longer useful to Eurycea rathbuni it was lost so the salamander today “has no eyes, only two small black dots under the skin” (TPWD) where its eyes used to be.

References

Audesirk, Gerald, Audesirk, Teresa and Byers, Bruce.   Biology: Life on Earth, 8^th Edition.  Pearson Education, 2008.

Texas Parks and Wildlife, Texas Blind Salamander (Eurycea rathbuni) June 2, 2009.  Web.  17 Apr. 2010 Retreived from http://www.tpwd.state.tx.us/huntwild/wild/species/blindsal/