How Can I Tell What Kind of Tadpoles I Have?

This is a tricky question and one that has befuddled many biologists for a long time. The easiest way, but not always 100% accurate, would be to find a frog near where you found the tadpoles and there’s a good chance they are the same species. If you can’t find an adult frog, do a little research on the amphibious wildlife indigenous to your area and you may be able to narrow it down a bit more. This won’t always give you a firm answer, as many areas will have several native species of frogs.

A more scientific method is through close observation and comparing your tadpole to a known chart. The below images and chart should help you get started.

First, where are the eyes? Are they lateral or dorsal?

Next, check the vent location. You may have to hold the tadpole in your hand to check this. Is it Medial or Dextral?

Next you’ll need to check the tail musculature. Is it high, medium or low?

And lastly, you’ll compare these results with the tadpole anatomy wheel below. (Click on the picture to see a full-size image.)

Following this procedure should give you a good idea and help you narrow it down. Of course, the only surefire way to identify the species will be to wait and see what kind of frog it grows into. The source of these images is the Tutorial on Tadpole Morphology from the U.S. Geological Survey (USGS).