pelvic fin

American  

noun

1. (in fishes) either of a pair of fins on the lower surface of the body, corresponding to the hind limbs of a land vertebrate; ventral fin.

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pelvic fin British  

noun

1. either of a pair of fins attached to the pelvic girdle of fishes that help to control the direction of movement during locomotion

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Etymology

Origin of pelvic fin

First recorded in 1905–10

Example Sentences

The new reconstruction of the skeleton also sheds light on specializations for head mobility in Tiktaalik and new details of the fish's pelvic fin anatomy.

From Science Daily • Apr. 5, 2024

These funny-looking fish latch onto rocks and seaweed, using a modified pelvic fin on their underside that acts like a suction cup to help them hang out until something tasty swims by.

From New York Times • Jul. 19, 2022

Phallon Tullis-Joyce will insist it was the Pacific spiny lumpsucker, a bony fish with a suction cup pelvic fin that helps it attach to surfaces.

From Seattle Times • Apr. 30, 2022

Other species of pupfish live across the south-western US, but Devils Hole pupfish are physiologically unique: they’re smaller and lack the pelvic fin that their cousins use to swim faster.

From The Guardian • Jul. 29, 2019

I drew a pectoral fin on the side and a pelvic fin on the bottom to help the shark move up and down.

From "The Line Tender" by Kate Allen