(of a fish's tail) appearing outwardly symmetrical but with the backbone passing into the upper lobe, as in all higher fish.
- ‘The tail fin of most ray-finned fish, with the exception of sturgeons and paddlefish, is homocercal, nearly symmetrical about the midline.’
- ‘This caudal fin structure contrasts with the externally symmetrical homocercal morphology present in most teleost fishes such as bluegill sunfish.’
- ‘Both mammals and reptiles returning to the sea developed quite workable homocercal tails in very short order.’
- ‘The current literature contains several hypotheses about the function of caudal fins of different shapes, and much of this discussion has focused on the difference between heterocercal and homocercal tails.’
- ‘Generally, osteolepiforms have homocercal, or even trilobate, tail fins.’
Mid 19th century: from homo- same + Greek kerkos tail + -al.