The Ancient Lung Fish
A Species from the Devonian Period That Used to Walk on Land
Evolution has not affected the Lung Fish and their internal organs have not changed for millions of years.
The Devonian is a geologic period of the Paleozoic era named after Devon England where Exmoor rocks from this period were studied. The Paleozoic era took place million of years ago and scientists claim the fish in this era had legs so they were able to walk on land as well as live in water.
Lung Fish do not have legs but they do have lungs. The internal organs of Lung Fish are fascinating to scientists because they are extremely rare and have not been caught up in evolution.
Species of Lung Fish
There are six species of Lung Fish alive today which live in the rivers and lakes of Africa, South America and Australia. The South American species are called Lepidosiren and African species are known as Protopterus. These two Lung Fish belong to the Lepidosirenidae family. The Australian Lung Fish, known as Neoceratodus, is the oldest of the species and belongs to the Ceratodidae family.
Lung Fish are long and slender which give them a snakelike appearance. The South American Lung Fish will grow to lengths well over three feet long and the African counterpart will reach lengths over six feet. They find their way around using their fins as sensors.
All six species breathe air, but some gulp it from the top of the water while others breathe it in through their gills. The Australian Lung Fish has only one lung but that’s due to being older than the South American and African species which have two lungs.
Australian Lung Fish will go to the surface to take in air when the waters are at their lowest levels during mid summer. Otherwise, the Australian Lung Fish prefers to take his oxygen through its gills. South American and African species have to go to the surface of the water to get air.
Lung Fish Spawning
For South American and African Lung Fish, both parents will put together a nest during spawning time. After the female lays the eggs in the nest, it is the male’s duty to watch over them till they hatch. The male will swim to the surface to get air then go right back to guard the nest. Lung Fish will fight to the death while protecting their eggs. The young fry have gills, but they slowly disappear as they mature.
Australian Lung Fish do not build a nest at spawning time. Once the mating has occurred, the female will lay the eggs at the bottom vegetation. She stays with the eggs until they hatch.
Lung Fish Hibernation
Another amazing fact about the Lepidosirenidae family is that they need little or no water to survive. When the heat in South America and Africa threatens the water supply, the Lung Fish digs down in the cool mud and buries itself until the water returns. The African Lung Fish does the same but it first covers itself with secretions produced by the body.
As the water levels lower, the mud dries to form a cocoon around the fish and they hibernate until water levels rise again. Their body functions slow down causing the Lung Fish to need very little to survive. Some Lung Fish, depending on the need, can hibernate up to two years.
Australian Lung Fish who belong to the Ceratodidae family, do not hibernate but they are quite capable of surviving in small bodies of water.
Lung Fish in Aquariums
Lung Fish are sometimes brought in as babies for the aquarium trade. Please don’t buy them because they grow very large and have a vise-like jaw that can deliver serious bites. In addition, they are extremely predatory and are known to eat aquarium heaters and decorations.
