Anatomy
C
~30,000 species
Caudal Fin
/ /ˈkɔːdj(ʊ)əl fɪn/ /
Etymology:
From Latin caudalis — "of the tail"
Quick Definition
The tail fin; the main propulsive organ in most fish.
📖 Full Definition
The caudal fin is the terminal median fin at the end of the tail. It is the principal organ of propulsion in most fishes. Caudal fin shape correlates strongly with swimming speed and style: forked or lunate tails (tuna, mackerel) indicate fast, continuous swimmers; rounded tails (perch) suit slower, manoeuvrable swimmers; truncate tails are intermediate. The caudal fin may be homocercal (externally symmetrical), heterocercal (upper lobe larger, as in sharks), or diphycercal (symmetrical with no external sign of asymmetry, as in lungfish).
💡 Examples & Context
The deeply forked, almost lunate caudal fin of the yellowfin tuna allows sustained speeds exceeding 70 km/h.