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Natural Highlights: Mississippi Map Turtle

  photo by Ben Grizzle

Mississippi Map Turtles (​Graptemys pseudogeographica kohnii​) are medium-sized aquatic turtles that occur from the southern portion of the Mississippi River basin westward to the Brazos River in Texas. They are often seen basking on logs and other objects in rivers and larger creeks. As with all Map Turtles, they can be easily distinguished by the pronounced keel that runs along the top of their shell. Unique to this species is the bright yellow or orange crescent-shaped marking behind the eye.  The oxbow at Kennedy Park, the lake edges at Epping Way, and the Wolf River itself are likely turtle-spotting places along the Wolf River Greenway.

Map Turtles specialize in feeding on shellfish and other invertebrates such as aquatic insects and crayfish. They are remarkable among turtles for their dramatic sexual dimorphism. Females often grow to twice the size of males!  As well as being much larger, females of many Map Turtle species develop greatly enlarged heads as they grow older, a phenomenon known as megacephaly. This adaptation allows large females to crush tough prey items like snails and mussels. Keep your eyes peeled for these unique turtles this summer, and be sure to document your findings (iNaturalist is a free app for uploading photos and other information into a international database).  

                                                                                                                                           - by Ben Grizzle, Bluff City Turtles

 

Posted by Cathy Justis at 11:45 AM