caudal keel

English

Tail of a Scombrid fish, showing the caudal keel and finlets

Noun

caudal keel (plural caudal keels)

1. (ichthyology) A lateral ridge found just anterior to each side of the tail fin on the caudal peduncle of some types of fast-swimming fish. The keels improve the stability of the fish's attitude at speed in the water, and strengthen the support of the caudal fin.