Lung fish
Lungfishes can be found in Australia, South America and Africa. There exist a total of six different species divided over two families. They all share the fact that they have developed lungs which allows them to breathe air in waters with low oxygen levels. These lungs are similar to those found in primitive amphibians.
Although it only exist six different species of lungfishes today there use to be much more species. All but six of these species are today extinct. Lungfishes can be traced back to the Lower Devonian area and they haven't changed much in the million of years that passed since then. In fact there are studies suggesting that the Australian lungfish haven't changed in 100 million years.
| The two families of lungfishes are Lepidosirenidae (South American lungfish and African lungfish) and Ceratodidae (Australian lungfish). All species have long snakelike bodies. All species of lungfishes grows large and the African lungfish can become over 6 feet / 2 m long. Lungfishes are predators and will eat anything they can get a hold of and that fits into there mouth. Their diet mainly consists of fish, crayfish, crabs and anything else meaty they might find. Lungfishes accepts most water conditions (although one should avoid to high pH levels) and can live in waters that other fishes couldn't survive in due to their ability to breathe air. Lungfishes in the Lepidosirenidae family can survive in very little and even without water. The South American lungfish do this by digging a hole in the bottom mud where they build a nest in which they remain until water levels raises again. The African lungfish have taken this a step further and covers their body with a secretion. This secretion dries to a leathery cocoon that helps the lungfish to survive until the water returns. The lungfishes remain dormant until the water returns and they will lower their metabolism during the hibernation period which allows them to consume very little to survive. They can survive up to two years in this way. The Australian lungfish doesn't hibernate in this manner instead they survive in whatever water remains by breathing oxygen. They can be found in very small water bodies. The species in the Lepidosirenidae family builds a nest for their eggs. The nest is protected by the male until the fry have hatched. The fry has gills which disappear as the fish grows older. The Australian lungfish does not build nest and they female deposit the eggs on the bottom within her habitat. |
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