The animal known for building large structures called dams is the beaver. Beavers are skilled engineers, using trees, branches, mud, and stones to construct dams in rivers and streams. These structures create ponds that serve as habitats for the beavers and protect them from predators. The construction of dams alters local ecosystems by creating wetlands, which can benefit various species and plant life. Beavers are known for their strong teeth and powerful jaws, enabling them to fell trees and gather materials for dam building, showcasing their remarkable adaptability and ingenuity.