Length 11 1/2 – 27 in. (30-51 cm). In spite of its formidable appearance, the Eastern Hellbender is quite harmless. Hellbenders can reach 27” in length making it the largest amphibian in the state. Found mostly in unglaciated (south and east) Ohio, Hellbenders prefer large, swift flowing streams where they hide during the day under large rocks. Although Hellbenders have lungs, the major organ of oxygen/carbon dioxide exchange is the loose wrinkled skin. Adult Hellbenders do not have gills but they do have a single gill slit located on each side of the neck. They breed in late August or September. The female lays up to 500 eggs in a nest the male excavates under a large flat rock. Sometimes several females use the same nest. Hellbenders differ from other salamanders in that the male does not fertilize the eggs until after they have been laid. Young Hellbenders hatch in two to three months and retain their gills until they are about 1 1/2 years old.
Text courtesy of the Ohio Division of Wildlife: https://wildlife.ohiodnr.gov/portals/wildlife/pdfs/publications/id%20guides/pub348.pdf