Amphibious fish are
fish
Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% ...
that are able to leave water for extended periods of time. About 11 distantly related
genera
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial ...
of fish are considered amphibious. This suggests that many fish genera independently
evolved amphibious traits, a process known as
convergent evolution
Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last com ...
. These fish use a range of terrestrial
locomotory modes, such as
lateral undulation,
tripod-like walking (using paired
fins and
tail), and jumping. Many of these locomotory modes incorporate multiple combinations of
pectoral-,
pelvic-, and tail-fin movement.
Many ancient fish had
lung-like
organs, and a few, such as the
lungfish and
bichir, still do. Some of these ancient "lunged" fish were the
ancestors of
tetrapod
Tetrapods (; ) are four-limb (anatomy), limbed vertebrate animals constituting the superclass Tetrapoda (). It includes extant taxon, extant and extinct amphibians, sauropsids (reptiles, including dinosaurs and therefore birds) and synapsids (p ...
s. In most recent fish
species
In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...
, though, these organs evolved into t