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.

English Transcript:

- [Narrator] Below the surface of the marsh, the roots of the papyrus jungle reached back in time to the domain of a creature that first settled here almost 400 million years ago, long before the dinosaurs. Like the papyrus plants, the African lungfish spans two worlds. This fish has gills, but it still needs air every half hour, otherwise it'll drown. Unlike most fish, it has a primitive lung, and what's more, it can perform a truly breathtaking feat. When the dry season comes and water turns to puddles and puddles turn into mud, the African lungfish finds himself in the thick of it. That's okay, the secret to lungfish longevity starts with a drought-defying burrow in the mud. About 10 inches below the surface, the fish spews mucus. It solidifies to form a cocoon-like shelter that traps moisture and lets in air. The lungfish enters excavation. While most animals burn fat for energy to keep alive, the lungfish digests muscle in its tail. It can survive for months until the season changes and salvation comes raining down upon it. Just a few days of rain changes everything, plunging Bengaluru underwater again. As the ground starts to soften, the lungfish rise like zombies all over the place. If need be, they could have waited two years or more. They climb back to the real world with help from their modified finger-like fins and hit the water. Then a quick drip to the surface for a refreshing gulp of air.

Spanish Translation:

- [Narrador] Bajo la superficie del pantano, las raíces de la jungla de papiro se remontan en el tiempo al dominio de una criatura que se asentó aquí por primera vez hace casi 400 millones de años, mucho antes de los dinosaurios. Al igual que las plantas de papiro, el pez pulmonado africano abarca dos mundos. Este pez tiene branquias, pero aún necesita aire cada media hora, de lo contrario, se ahogará. A diferencia de la mayoría de los peces, tiene un pulmón primitivo, y además, puede realizar una hazaña verdaderamente impresionante. Cuando llega la temporada seca y el agua se convierte en charcos y los charcos se convierten en lodo, el pez pulmonado africano se encuentra en medio de todo. Está bien, el secreto de la longevidad del pez pulmonado comienza con una madriguera en el lodo que resiste las sequías. A unos 25 centímetros bajo la superficie, el pez expulsa mucosidad. Se solidifica para formar un refugio similar a un capullo que atrapa la humedad y deja entrar aire. El pez pulmonado entra en excavación. Mientras que la mayoría de los animales queman grasa para obtener energía y mantenerse vivos, el pez pulmonado digiere el músculo de su propia cola. Puede sobrevivir durante meses hasta que cambia la estación y la salvación le llueve desde el cielo. Solo unos días de lluvia cambian todo, sumergiendo a Bengaluru bajo el agua nuevamente. A medida que el suelo comienza a ablandarse, los peces pulmonados emergen como zombis por todas partes. Si fuera necesario, podrían haber esperado dos años o más. Vuelven al mundo real con ayuda de sus aletas modificadas en forma de dedos, y se lanzan al agua. Luego, un rápido ascenso a la superficie para dar un refrescante sorbo de aire.