Is dugongs are Structural adaptation

Dugongs have similar adaptations to whales and dolphins. They look rather like rotund grey-brown dolphins with a fish-like shape, flippers and tails and grow up to three metres long and weigh up to 400kg. Their skin is thick and smooth, with the nostrils near the front of the head enabling them to breath with most of the body beneath the surface. Unlike other mammals, dugongs cannot hold their breath under water for very long. The adaptation is their heavy bones so that they can stay underwater and also their liver, as it removes all of the salt from the plants it eats. Its snout is turned downwards. This adaptation helps the dugong extract its food from the ground.