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Fish of the Day

Happy Thursday, everyone! Today's fish of the day is the Australian lungfish!

The Australian lungfish, or barramunda, known by scientific name Neoceratodus forsteri is one of the 6 surviving lungfishes of the modern world. The other 5 lungfishes are scattered to other sections of the world, one in South America, and the other 4 all living in Africa. As the name implies, this lungfish is endemic to Australia living in South Eastern Queensland, or for those who don't know the general areas of Australia, the upper right corner of the country. Living exclusively in slow moving streams, still waters, and various waterside banks living entirely in freshwater systems. This fish is primarily nocturnal, and almost entirely carnivorous. Its diet consists of: frogs, larvae, bugs, plant material, earthworms, fishes, small invertebrates, and anything else it can catch. They are primarily bottom dwellers, and prey is caught directly in the mouth and then crushed multiple times, being positioned correctly by a bone called a hydroid apparatus. Australian lungfish have the most primitive of surviving lungfish feeding behaviors.

Australian lungfish are best known for their ability to survive dry seasons. However, unlike African lungfish, which can survive fully in droughts by submerging themselves into This is done by submerging the body in the mud, and rising to the surface to swallow oxygen into a single dorsal lung. This lung is only supplementary, and the fish prefer to breathe through their 5 gills. Of the six lungfish, the Australian lungfish is the only one to not have two lungs, but rather a fold down the center of the single lung acting as a wall, which blood capillaries run through, allowing gas exchange. Unlike it's African counterparts, the Australian lungfish can not survive total water depletion, (other lungfish survive this by creating a layer of mucus around itself and living there for several years until water returns). Australian lungfish can survive several days out of the water, but can not do so unless it is in a moist environment, usually mud.

Fossil records of lungfish tell us that some of their first fossils can be found from 410 Million years ago, being the closest living relative to the tetrapod. The last shared ancestor between the lungfish and tetrapod was 420 Million year ago. Originally, these animals started as marine creatures, but sometime in the carboniferous the species became freshwater exclusive, around the same time that the last common ancestor to all remaining lungfish lived. Australian lungfish in particular appear to have split off about 380 million years ago, and have remained virtually unchanged from their ancestors for over 100 million years, giving them the title of living fossils!

Not only have they remained incredibly similar over the years, they have a long lifespan for individuals as well. A captive Australian lungfish named granddad was shown to live to 108 years (+- 6), with the expected lifespan of wild lungfish surviving at least 20-25 years after they reach sexual maturity. In Australian lungfish, similar to other lungfish species in the world, sexual maturity is reached in males after 17 years, and 22 years in females. Australian lungfish have elaborate courting rituals consisting of three distinct phases. The first phase is searching, where the lungfish will breathe loudly, making mating calls with its single lung. The second is called "follow the leader" where males will attempt to entice a female by nudging and rubbing snouts with her, often at the same time as competitors. The last stage is where two lungfish will descend to lay and fertilize eggs, females producing 2 eggs per spawning season. After breeding, the eggs are left to sink in the vegetation, as Australian lungfish do not nest or care for their young. This is unlike all other lungfish species.