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.

  1. How has the West African lungfish’s primitive lung helped the species survive for more than 300 million years?

    • Answer

      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.

  2. How has the West African lungfish’s estivation behavior helped the species survive for more than 300 million years?

    • Answer

      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.

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 riverbed. 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.

Noun

a modification of an organism or its parts that makes it more fit for existence. An adaptation is passed from generation to generation.

Noun

layer of gases surrounding Earth.

aquatic
Adjective

having to do with water.

behavioral adaptation
Noun

way an organism acts in order to survive or thrive in its environment.

biological adaptation
Noun

physical change in an organism that results over time in reaction to its environment.

burrow
Verb

to dig a small hole or tunnel.

cocoon
Noun

silky covering spun by silkworms and other insect larvae in which they live and develop during the pupal stage.

consume
Verb

to use up.

digestion
Noun

process in breaking down ingested food into easily absorbed and assimilated substances by the action of enzymes and other agents.

dormant
Adjective

state of minimal growth or activity.

dry season
Noun

time of year with little precipitation.

earth
Noun

soil or dirt.

estivation
Noun
inactive state resembling deep sleep, in which some animals living in hot climates pass the summer.
excrete
Verb

to discharge a substance from the body.

extract
Verb

to pull out.

furious
Adjective

having a wild or violent passion.

gills
Plural Noun

respiratory organs that draw oxygen from water and into the bloodstream.

Noun

environment where an organism lives throughout the year or for shorter periods of time.

hibernation
Noun

state of reduced physiological activity, similar to sleep, in which some animals spend the winter.

Noun

body of water surrounded by land.

Noun

the geographic features of a region.

living fossil
Noun

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
Noun

organ in an animal that is necessary for breathing.

metabolism
Noun

chemical changes in living cells by which energy is provided for vital processes.

moisture
Noun

wetness.

mucus
adjective, noun

slimy, fluid secretion of some animals.

mud
Noun

wet soil.

muscle
Noun

tissue found in animals that expands and contracts, allowing movement.

Noun

substance an organism needs for energy, growth, and life.

obtain
Verb

to get or take possession of.

organism
Noun

living or once-living thing.

physical
Adjective

having to do with the body.

pond
Noun

small body of water surrounded by land.

prehistoric
Adjective

period of time that occurred before the invention of written records.

prepare
Verb

to assemble or get ready for something.

primitive
Adjective

simple or crude.

prior
Adjective

before or ahead of.

protect
Verb

to take action to prevent injury or attack.

rainy season
Noun

time of year when most of the rain in a region falls.

remarkable
Adjective

unusual and dramatic.

respiration
Noun

breathing.

restore
Verb

to renew or bring back to an earlier position or state of health.

tissue
Noun

cells that form a specific function in a living organism.