1) Webbed feet are useful to ducks because they use their feet to swim. Their webbed feet are uniquely designed to help them move through the water. ... Ducks use their webbed feet like paddles to provide more surface to push against the water.
2) Shells are useful to snails because snails and clams are calcium carbonate while the endoskeleton of vertebrates like turtles are primarily calcium phosphate is not known. Both shells are strong, allow for protection, attachment of muscles and resist dissolution in water.
3) Long arms are useful to gibbons because It allows them to reach average speeds of about 35 miles per hour and propel themselves from one tree to another over distances of up to 50 feet.
