Lung fish are a rare group of very primitive fish that can breathe air.All living species in this group live in the southern hemisphere of the planet and, as aquatic animals, their biology is largely determined by this medium.
In this article by Animal Expert, we will delve into the world of lung fish, as they are, how they breathe, and see some examples of species of lung fish and their characteristics.
- Dipnoic or pulmonary fish are a group of fish belonging to the sarcopterigio class.
- In which lobed or fleshy fin fish are classified.
The taxonomic relationship between the pulmonated fish and other fish generates much controversy and dispute among the researchers, if, as believed, the current classification is correct, these animals must be closely related to the group of animals (Tetrapodomorpha) that gave birth to the current one.traped vertebrates.
Currently six species of lung fish are known, grouped into two families, lepidosirenidae and Ceratodontidae; epidosirdends are organized into two genes, protopterus, in Africa, with four living species, and the genus Lepidosiren in South America, with a single species.The cerantodontidae family has only one species, in Australia, Neoceratodus fosteri, which is the most primitive live lungfish.
As we said, lung fish have lobed fins and, unlike other fish, the spine reaches the tip of the body, where they develop two folds of skin that act as fins.
They have two functional lungs in adulthood. These come from the ventral wall at the end of the pharynx, in addition to the lungs, have gills, but retain only 2% of the breathing of the adult animal, during the larval phases these fish breathe through the gills.
They have nasal openings, but they don’t use them for air, but they have an olfactory function.Its body is covered with very small scales embedded in the skin.
These fish live in shallow inland waters and, during the dry season, sink into the clay, entering a kind of hibernation or lethargy.They cover their mouths with a clay “cap” that has a small hole through which the air needed to breathe can enter.They are oviparous animals and the male takes care of the offspring.
Lung fish have two lungs and a circulatory system with two circuits.These lungs have many ridges and partitions to increase the surface of gas exchange and are also highly vascularized.
To breathe, these fish rise to the surface, open their mouths and widen the oral cavity, forcing air in, then they close their mouths, compress the oral cavity and the air passes into the anterior lung cavity, while the mouth and anterior The lung cavity remains closed, the posterior cavity contracts and exhales air inspired by the anterior breath, allowing this air to escape through the lids (where the gills are normally found in aquatic breathing fish). The chamber contracts and opens, allowing air to pass into the rear chamber, where gas exchange will take place. Then see the lungfish, examples and a description of the best known species.
The pyramboia (Lepidosiren paradoxa) is one of the fishes, distributed in the river areas of the Amazon and other regions of South America, its appearance resembles that of an eel and can reach more than one meter in length.
It lives in shallow and preferably calm waters. When summer arrives with droughts, this fish makes a hole in the clay to maintain moisture, leaving holes to allow lung breathing.
Protopterus annectens is one of the species of lung fish living in Africa.It is also shaped like an eel, although the fins are very long and filamentous.It lives in the countries of West and Central Africa, but also in a certain eastern region.
This fish has nocturnal habits and during the day remains hidden in the aquatic vegetation, during droughts they dig a hole through which they penetrate vertically so that the mouth keeps in contact with the atmosphere, if the water level descends below its hole, they begin to secretly mucus to maintain moisture in its body.
The Australian lung (Neoceratodus forsteri) inhabits southwest Queensland, Australia, the Burnett and Mary rivers, has not yet been evaluated by the IUCN, so its conservation status is unknown, but is protected by the CITES agreement.
Unlike other lungs, Neoceratodus forsteri has only one lung, so it cannot rely solely on air respiration. This fish lives deep in the river, hides during the day and moves slowly on the muddy bottom at night. They are large animals, more than a meter long in adulthood and weighing more than 40 kilos.
When the water level drops due to drought, these lung fish stay at the bottom because they have only one lung and also have to perform aquatic respiration through the gills.
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