Biologist Nathan Mineo

Did You Know...?

Spea Can Change From Omnivores to Carnivores

Written by Nathan Mineo 
Reprinted from the 2008 Cape Ann Vernal Pond Team Newsletter
Photograph by Cheryl Briscoe

Did you know that Spadefoot toad tadpoles (genus Spea) can change from omnivores to carnivores depending on their diet? Tadpoles hatch as omnivores and then start feeding. Those individuals that make a meal out of Fairy shrimp become carnivores while those that do not, remain omnivores and continue to feed mainly on detritus. The ingestion of Fairy shrimp triggers a morphological change in the tadpoles: their body narrows, intestine shortens, and they develop enlarged jaw muscles and notched mouthparts.

This amazing phenomenon is known as "developmental plasticity" -- the process by which environmental factors change the course or an organism's development -- and is being studied in Spea tadpoles by Dr. David Pfennig of UNC. For more information, visit Dr. Pfennig's lab page: www.bio.unc.edu/faculty/pfennig/Lab/Welcome.html