Why do fish have vertical tail fins and whales have horizontal

By A Mystery Man Writer

The Difference Between Sharks and Dolphins

Mark P. Witton's Blog: A tale of plesiosaur tails: vertical fins or horizontal flukes?

Why do some fish have vertical tails, and others have horizontal tails? - Quora

science based - Is it more likely that merfolk would evolve with horizontal or vertical tails? - Worldbuilding Stack Exchange

Rhincodon typus – Discover Fishes

Why fish have vertical fins, and dolphins and whales not? — Steemit

Fish fin - Wikipedia

Evolution of Dolphins - microbewiki

Tails you win Sussex Wildlife Trust

실제 고래의 뒷다리와 꼬리뼈는 어떻게 생겼을까? - 포텐 터짐 최신순 - 에펨코리아

Ask Dr. Universe: Evolution gave marine mammals horizontal tails

Cetacea - Wikipedia

Facts - Adopt a Dolphin

Why do some fish have vertical tails, and others have horizontal tails? - Quora