What mammals don't have ear flaps?

Mammals that lack external ear flaps, or pinnae, include some species of cetaceans (like whales and dolphins) and certain species of amphibious mammals, such as the manatee. These animals have evolved to thrive in aquatic environments, where external ear structures are unnecessary and could even impede their movement. Additionally, some burrowing mammals, like moles, also lack prominent ear flaps, as their adaptations prioritize life underground.