Also found in: Dictionary, Thesaurus, Encyclopedia, Wikipedia.
Dipnoia subdivision of the CHOANICHTHYES containing the only three living species of lungfish, though the group was common in the DEVONIAN PERIODS and CARBONIFEROUS PERIODS. The air bladder is developed as a lung for air breathing and this facilitates survival during dry seasons.
lungfish. Fish that breathe through gills when in water but through lungs when out of it. Their peculiarity is that their nasal cavities, which are blind-ended, olfactory organs in most fish, connect with the roof of the mouth.