Loon Adaptations: The Body
Designed to Work Like a Submarine

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  • Loons have powerful leg muscles to allow them to paddle above water, and to propel them with speed and power below water. The legs are set at the very back of the body to give it the most power when swimming. This makes it very hard for loons to walk on land, but since their swimming specialists, that doesn't matter for the kind of life they lead.
  • Loon toes are webbed to make them better at pushing water for effective swimming.
  • Loons have wings that are exactly the right size for the way they live. Big airy feathers make all wings very buoyant. If loon wings were a little bigger, they would make the loon pop back up to the surface like a cork when it was trying to dive. If they were a little smaller, they couldn't support the loon's body in flight.
  • Large breast muscles give loons thick, dense tissue in their center of gravity for more controlled diving and swimming.
  • Loons must flap their small wings fast to keep their heavy bodies up in the air. The powerful breast muscles, rich in red muscle fibers, get a huge blood supply so they have the oxygen and energy to flap fast for long periods of time.
  • Loons have big air sacs inside their body. When they breathe in, they can fill these air sacs to capacity, which makes their bodies expand to be a little bigger, and makes them float. When they breathe out, they usually keep the air sacs partly full, but they can push out most of the air in their air sacs, making their bodies a little smaller and helping them to sink. If a predator approaches, a loon can quietly sink into the water without leaving a ripple. If it's chasing a fish fairly deep in the water, the partly deflated airsacs make it dense enough to easily stay underwater for over a minute before it needs to come up for air.
  • The body shape is torpedo like, helping the loon to conserve energy while diving and swimming.
  • Thick, dense body feathers keep the loon waterproof and hold its heat in even in frigid Arctic waters.
  • The design of the plumage makes loons look a little like the sparkling water.