The lungfish is the animal that has both gills and lungs.
Lungfish: A Unique Respiratory System
Lungfish are a fascinating group of freshwater fish characterized by their unique ability to breathe both through gills (like most fish) and lungs (like terrestrial vertebrates). This dual respiratory system allows them to survive in oxygen-poor waters and even out of water for extended periods.
Adaptations for Breathing
- Gills: Lungfish possess gills that enable them to extract oxygen from the water, similar to other fish species.
- Lungs: In addition to gills, lungfish have one or two lungs, which are modified swim bladders. These lungs allow them to breathe air directly, supplementing or replacing gill respiration when oxygen levels in the water are low.
Lungfish Species
There are six known species of lungfish found in Africa, South America, and Australia. These species exhibit varying degrees of dependence on their lungs:
- African Lungfish (Protopterus): Highly dependent on their lungs and can survive out of water for months by estivating in mud.
- South American Lungfish (Lepidosiren paradoxa): Also highly dependent on their lungs, especially during the dry season.
- Australian Lungfish (Neoceratodus forsteri): Less dependent on their lungs compared to African and South American species and relies more on gill respiration.
Evolutionary Significance
Lungfish are considered to be among the closest living relatives of tetrapods (four-limbed vertebrates), providing valuable insights into the evolutionary transition from aquatic to terrestrial life. Their ability to breathe air using lungs is a key adaptation that may have paved the way for the evolution of land-dwelling vertebrates.
