In larval lampreys, called ammocoetes, their mouth is not fully developed, very small, and hidden between folds of skin.

As ammocoetes, Ohio lamprey filter plankton, algae, and other small organic matter.

As adults, they attach onto larger prey, such as smallmouth bass, walleyes, redhorse suckers, and trout, feeding on blood and body fluids.

Spawning occurs in late May or early June, with adults working together or in pairs to create a pit in riffles of moderate currents.

They use their suction cup-like mouth to move rocks from these riffles, and then the female lamprey deposits eggs into this pit after mating.