Answer:
Webbed feet
Step-by-step explanation:
Ducks are a species of birds that usually spend most of their time in water. The feed and breed around waterbodies such as lakes, marshes, rivers and streams. To enable them thrive in their water environment, ducks have developed several structures. One of such structure is the webbed design of their feet. This design enables them to swim much better and faster in order to hunt for food or to avoid predators. Recent research have discovered that while swimming, ducks push both backward and downward with each stroke of their webbed feet. This provides a combination of lift and thrust, assisting them to move through water with greater speed and efficiency.
Other important features of the duck include the preen gland (uropyial gland) which produces oil that keeps the ducks feather from getting wet while in water, thus assisting them to float; hollow bones which makes them lightweight, etc.