West African Lungfish A living fossil s biological and behavioral adaptations

Transcription

1 VideoMedia Spotlight West African Lungfish A living fossil s biological and behavioral adaptations For the complete video with media resources, visit: Funder West African lungfish are prehistoric animals. They have survived unchanged for so long (nearly 400 million years) that they are sometimes nicknamed living fossils. West African lungfish have remarkable adaptations that have helped them survive: a primitive lung and the ability to survive in a state of estivation, which is similar to hibernation. A lungfish s lung is a biological adaptation. A biological adaptation is a physical change in an organism that develops over time. Like all fish, lungfish have organs known as gills to extract oxygen from water. The biological adaptation of the lung allows lungfish to also extract oxygen from the air. A lungfish s estivation also involves a number of biological adaptations, including the excretion of a mucus cocoon and digestion of the fish s own muscle tissue to obtain nutrients. A lungfish s estivation also includes a behavioral adaptation. A behavioral adaptation describes a way an organism acts. Prior to estivation, lungfish furiously burrow into the muddy ground. The behavioral adaptation of burrowing allows lungfish to create a protected habitat where they can survive during a long period of dormancy. Watch this video, from the Nat Geo WILD series Destination Wild, and use our glossary to help answer questions in the Questions tab. Learn more about these fascinating fish with our Fast Facts. Questions How has the West African lungfish s primitive lung helped the species survive for more than 300 million years? 1 of 5

2 During the dry season, the West African lungfish can breathe (extract oxygen from the air) as lakes and ponds turn to mud and cracked earth. As the rainy season restores the lungfish s aquatic habitat, it can rely mostly on its gills to extract oxygen from the water. How has the West African lungfish s estivation behavior helped the species survive for more than 300 million years? The lungfish creates a mucus cocoon prior to estivation. The cocoon traps moisture and lets in air as the fish estivates. As the metabolism of the lungfish slows, it digests muscle in its tail to consume nutrients and stay alive. The burrowing, mucus cocoon, and self-digestion allow the lungfish to survive years beneath the dry landscape. Fast Facts The West African lungfish digs its burrow using its mouth. It chews through the moist earth, excreting the mud through its gills. West African lungfish have a very slow metabolism. This means they are much less active than other fish, and often rest at the bottom of a lakebed or ried. In fact, West African lungfish are so inactive that many aquarium owners mistakenly think their fish is dead! The largest specimen of West African lungfish was a meter (3.3 feet) long and weighed a whopping 4 kilograms (nearly 9 pounds). The West African lungfish is an omnivore. It feeds on everything from frogs, fish, and mollusks to tree roots and seeds. Although larger fish and mammals may prey on juvenile lungfish, the adult lungfish has no major predators. There are four species of African lungfish. (The one in the Destination Wild video is the West African lungfish, found in freshwater habitats throughout sub-saharan Africa.) Other species of lungfish are indigenous to Australia and South America. Vocabulary Term adaptation a modification of an organism or its parts that makes it more fit for existence. An adaptation is passed from generation to generation. air layer of gases surrounding Earth. aquatic having to do with water. behavioral adaptation way an organism acts in order to survive or thrive in its environment. 2 of 5

3 Term biological adaptation physical change in an organism that results over time in reaction to its environment. burrow cocoon to dig a small hole or tunnel. silky covering spun by silkworms and other insect larvae in which they live and develop during the pupal stage. consume to use up. digestion process in breaking down ingested food into easily absorbed and assimilated substances by the action of enzymes and other agents. dormant state of minimal growth or activity. dry season time of year with little precipitation. earth soil or dirt. estivation inactive state resembling deep sleep, in which some animals living in hot climates pass the summer. excrete to discharge a substance from the body. extract to pull out. furious having a wild or violent passion. gills habitat plural respiratory organs that draw oxygen from water and into the bloodstream. environment where an organism lives throughout the year or for shorter periods of time. hibernation condition, similar to sleep, in which some animals spend the winter. lake body of water surrounded by land. landscape the geographic features of a region. living fossil organism that is a living example of an otherwise extinct group or that has remained virtually unchanged in structure and function over a long period of time. lung organ in an animal that is necessary for breathing. metabolism chemical changes in living cells by which energy is provided for vital processes. 3 of 5

4 Term moisture wetness. mucus mud, slimy, fluid secretion of some animals. wet soil. muscle nutrient obtain tissue found in animals that expands and contracts, allowing movement. substance an organism needs for energy, growth, and life. to get or take possession of. organism living or once-living thing. physical having to do with the body. pond small body of water surrounded by land. prehistoric period of time that occurred before the invention of written records. prepare to assemble or get ready for something. primitive prior simple or crude. before or ahead of. protect rainy season to take action to prevent injury or attack. time of year when most of the rain in a region falls. remarkable unusual and dramatic. respiration breathing. restore tissue to renew or bring back to an earlier position or state of health. cells that form a specific function in a living organism. Images Primitive Fishes: Lungfishes Video BBC: The Lung Fish Websites Oregon Zoo: African Lungfish 4 of 5

5 National Geographic Society. All rights res erved. 5 of 5