https://creativecommons.org/publicdomain/zero/1.0/https://www.rawpixel.com/image/4022266
Whale fluke.
Whale fluke.
A whale's tail is made of two lobes separated by a deep notch. Unlike fish, which have vertical tails, the whale's tail is on a horizontal plane when his body's upright. Another difference between flukes and fish tails is that flukes don't contain bones. They are made up of dense, fibrous connective tissue surrounded by a network of arteries and veins. Long muscles that run above and below the backbone move the flukes up and down. Original public domain image from Flickr
Public DomainFree CC0 image for Personal and Business use