Newly discovered lymph hydraulics give tunas their fancy moves

Long-overlooked anatomy raises fishes’ fins for zigs, zags and tight turns

Big tuna

FINTASTIC A sickle-shaped fin on the back of a tuna and one underneath contain shape-shifting systems that scientists have just discovered.

Monterey Bay Aquarium

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In fishes as familiar as tunas, humans have managed to find some unknown anatomy: a hydraulic system based on lymph.