| Tonguefish | |
|---|---|
 | |
| Northern tonguefish,Symphurus pusillus | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Carangiformes |
| Suborder: | Pleuronectoidei |
| Family: | Cynoglossidae Jordan, 1888 |
| Subfamilies & genera[1] | |
SubfamilyCynoglossinae SubfamilySymphurinae | |
Tonguefishes areflatfish in thefamilyCynoglossidae. They are distinguished by the presence of a long hook on the snout overhanging the mouth, and the absence of pectoral fins. Their eyes are both on the left side of their bodies, which also lack a pelvic fin.[2] This family has threegenera with a total of more than 140 species. The largest reaches a length of 66 cm (26 in), though most species only reach half that size or less.[3][4][5] They are found intropical andsubtropical oceans, mainly in shallow waters andestuaries, though some species are found in deepsea floors,[6] and even a few inrivers.
Symphurus thermophilus lives congregating around "ponds" ofsulphur athydrothermal vents on the seafloor. No other flatfish is known from hydrothermal vents.[7] Scientists are unsure of the mechanism that allows the fish to survive and even thrive in such a hostile environment.[8]
