Transcript:

Today on Animal Fact Files we’re discussing lungfish. As their common name implies, these fish use lung-like structures to breathe, but it's different depending on the species. There are six living lungfish species found in Africa, South America, and Australia. The African and South American species are more similar to each other than the unique Australian species. Australian lungfish have scales, they do not require air for breathing, and they don't burrow into the mud to wait out dry parts of the year. In contrast, South American and African lungfish do not have scales, would drown if held underwater for too long, and create burrows in which they rest for part of the year. In the case of the African lungfish, a cocoon is developed around the estivating animal's body which provides protection from pathogens. 

All living lungfish species spend their time in freshwater. They live in swamps, streams, lakes, rivers, and more, and use their tetrapod-like limbs for crawling along the bottom of their home. During periods of drought, lungfish use their modified swim bladder as a means of breathing atmospheric air. It's believed these fish could show a glimpse into the past for how animals eventually moved from water to land. In fact, when first described, there was debate on whether or not these animals were fish or amphibians! Today they're considered fish, hence their common name - otherwise we might be calling them lung salamanders!

Surprisingly, these fish can reach considerable sizes. Depending on the species they range anywhere from four feet to seven feet (122-213cm) in length! Even at that size they can dig into the mud and live in a cocoon for months to years on end! In laboratory settings, African lungfish have been recorded remaining in their burrow up to four years. Their metabolic rate drops, so they don't need to eat, but when they aren't snoozing away the dry months, these fish eat other fish, frogs, molluscs, crustaceans, worms, aquatic plants, fruits and insects that have fallen into the water, and more. They have plate-like teeth used for crushing and chewing their food, something most fish don't do!

When it comes to breeding behavior and development, Australian lungfish once again stand out from African and South American lungfish species. As juveniles, Australian lungfish do not possess external gills. On the other hand, juveniles of African and South American lungfish species do have external gills, like an axolotl, which are lost as they enter adulthood. All lungfish species produce eggs. These are fertilized via spawning, typically when waters are at their highest and warmest. Often, shallow water is used for spawning aggregations, and the large eggs may adhere to vegetation or be deposited in a protected area. The male lungfish guards the eggs from threats like other fish and wandering invertebrates. Depending on the species it takes a few weeks to just over a month for the eggs to hatch. As juveniles, lungfish may be taken by members of their own species and eaten by larger predators like wading birds and Tasmanian devils. Adults have few predators but these animals are known to be eaten by humans in some parts of their range. If they can avoid predation, lungfish can live decades in the wild.

For more facts on lungfish, check out the links below. Give a thumbs up if you learned something new today. Thank you to our Patrons SpikeSpiegel93, Dad, and everyone else for their support of this channel! And thank you for watching Animal Fact Files!