Lungfish

Lungfish

Lungfish are considered to be the most primitive living fishes. There are 3 families and 6 extant species of these ancient fishes.

• Australian lungfish (Family Ceratodontidae): 1 species
• African lungfish (Family Protopteridae): 4 species
• South American lungfish (Family Lepidosirenidae): 1 species

The Australian lungfish is considered the most primitive extant species of lungfish.

Members of these species possess 1 lung (Australian lungfish) or 2 lungs (South American, African lungfish) which they use to breathe atmospheric oxygen. When young, lungfishes possess external gills, which are lost when they grow up.

Their teeth fuse together to the form tooth plates which they use to chew their food.

Photos:

References:

http://biology.livejournal.com/185482.html

http://primitivefishes.com/lungfishes