lungnakerfisins

The term "lungnakerfisins" is an Icelandic word that translates directly to "lung fish." This refers to a group of freshwater fish belonging to the order Dipnoi. Lungfish are characterized by their ability to breathe air using a lung-like organ in addition to their gills. This adaptation allows them to survive in environments where water oxygen levels are low or even during periods of drought when their habitat may dry up.

There are six known extant species of lungfish, divided into three families: Neoceratodontidae (one species, the Australian lungfish), Lepidosirenidae (one species, the South American lungfish), and Ceratodontidae (four species, the African lungfish). These fish are found in freshwater habitats in Africa, South America, and Australia.

Lungfish are carnivorous and typically feed on invertebrates, amphibians, and smaller fish. They are known for their elongated, eel-like bodies, though the Australian lungfish has a more robust form. Their fins are often filamentous. Many lungfish species can enter a state of estivation, burrowing into mud and secreting a mucus cocoon to survive dry seasons. This remarkable ability to breathe air and survive drought has made them a subject of significant scientific interest, particularly in understanding the evolution of tetrapods from fish.