By Stacey Venzel
Turtles have a good sense of hearing, but not up to par with humans. A turtle’s ears look different from what most people likely imagine when thinking of ear anatomy.
As chelonians have a range of terrestrial and aquatic habitats, the turtle ear evolved to accommodate both environmental settings. Turtles can rely on hearing for navigation, mating, hunting, foraging and predator avoidance.
Instead of an outer ear, turtles have a thin skin membrane that externally covers the ear canal. Vibrations inside the middle ear detect sound.
Studies on the amphibious red-eared slider and the strictly marine green sea turtle showed that turtles’ ears are specialized for underwater hearing. Both can detect lower frequencies than humans but have a much smaller range. Their sound detection, from zero to 1,000 Hertz, is most effective in water at around 400 Hertz. Some turtles, like the South American arrau turtle, use low-frequency echolocation to communicate. Others, like the northern snake-necked turtle, listen for mating calls breeding season.
John H Anderson, James G McCormick, Jerry Palin, Et. Al., “Hearing in the giant sea turtle, Chelonia mydas,” Proceedings of the National Academy of Sciences of the United States of America, November 1969,http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3367789/.
Christian Brandt, Catherine E Carr, Christian B Christensen, Et. Al., “Specialization for underwater hearing by the tympanic middle ear of the turtle, Trachemys script elegans,” Proceedings of the Royal Society B: Biological Sciences, March 21, 2012,http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3367789/.
Jenny A Davis, Jacqueline C Giles, Gerald Kuchling, Et. Al., “Voice of the turtle: The underwater acoustic repertoire of the long-necked freshwater turtle, Chelodina oblonga,” The Journal of the Acoustical Society of America,http://scitation.aip.org/content/asa/journal/jasa/126/1/10.1121/1.3148209.
Karen Eckert, David Gulko, Sea Turtles: An Ecological Guide (Honolulu, Mutual Publishing, 2004), 24.
George M Strain, “How well do dogs and other animals hear?” Louisiana State University, September 18, 2015,http://www.lsu.edu/deafness/HearingRange.html.