Interesting Facts About Lungfish: It Can Be Extremely Long-Lived

Nature never stops amazing us! From flora to fauna, nature’s arsenal of creations is probably far beyond human comprehension. The Lungfish is just yet another of such miraculous creations that we come across.
Lungfish are freshwater rhipidistian fish belonging to the subclass Dipnoi. Lungfish are best known for retaining characteristics primitive within the Osteichthyes, including the ability to breathe air, and structures primitive within Sarcopterygii, including the presence of lobed fins with a well-developed internal skeleton.
Today there are only six known species of lungfish, living only in Africa, South America and Australia. While vicariance would suggest this represents an ancient distribution limited to the Mesozoic supercontinent Gondwana, the fossil record suggests advanced lungfish had a widespread freshwater distribution and the current distribution of modern lungfish species reflects extinction of many lineages subsequent to the breakup of Pangaea, Gondwana and Laurasia.
Today, we are going to share with you SEVEN interesting facts about Lungfish you probably didn’t know.
1. Lungfish are omnivorous, feeding on fish, insects, crustaceans, worms, mollusks, amphibians and plant matter. They have an intestinal spiral valve rather than a true stomach.
2. The dentition of lungfish is different from that of any other vertebrate group. “Odontodes” on the palate and lower jaws develop in a series of rows to form a fan-shaped occlusion surface. These odontodes then wear to form a uniform crushing surface. In several groups, including the modern lepidosireniformes, these ridges have been modified to form occluding blades.
3. African and South American lungfish are capable of surviving seasonal drying out of their habitats by burrowing into mud and estivating throughout the dry season. Changes in physiology allow it to slow its metabolism to as little as 1/60th of the normal metabolic rate, and protein waste is converted from ammonia to less-toxic urea (normally, lungfish excrete nitrogenous waste as ammonia directly into the water).
4. Lungfish can be extremely long-lived. A Queensland lungfish at the Shedd Aquarium in Chicago was part of the permanent live collection from 1933 to 2017, when it was euthanized following a decline in health consistent with old age.
5. Lungfish have a highly specialized respiratory system. They have a distinct feature that their lungs are connected to the larynx and pharynx without a trachea. While other species of fish can breathe air using modified, vascularized gas bladders, these bladders are usually simple sacs, devoid of complex internal structure. In contrast, the lungs of lungfish are subdivided into numerous smaller air sacs, maximizing the surface area available for gas exchange.
6. Of extant lungfish, only the Australian lungfish can respire through its gills. In other species, the gills are too atrophied to allow for adequate gas exchange. When a lungfish is obtaining oxygen from its gills, its circulatory system is configured similarly to the common fish.
7. Most extant lungfish species have two lungs, with the exception of the Australian lungfish, which only has one. The lungs of lungfish are homologous to the lungs of tetrapods. As in tetrapods and bichirs, the lungs extend from the ventral surface of the esophagus and gut.

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