Lungfish have been proposed as a link between sea and land animals because they have the ability to survive for long periods out of the water. There are many varieties of lungfish found in Australia, Africa, and South America. In Australia they live in quiet pools of water which become stagnant in the summer. Because there isn't much oxygen dissolved in the water, these fish need lungs in order to breathe air, just as we do. Lungfish in South America live in swamps which dry up during the dry season. They spend the dry season resting in burrows. The African lungfish also spends the dry season burrowed in the mud, but it builds a breathing tube through the mud to allow air to reach it.
Lungfish are not fish in the process of evolving into land animals-they are simply animals designed to survive for periods of time outside of water. Lungfish lack critical biological features such as bones and muscles for movement on land. This makes it impossible for them to ever become anything other than a fish. Furthermore, the lungfish we find living today are exactly the same as those which are found in the fossil record. There is absolutely no evidence that a lungfish has ever been, or ever will be, anything other than a lungfish.
From A Closer Look at the Evidence by Kleiss, April 14.
