Giant willow aphids (Tuberolachnus salignus), pictured, are about 6mm long with a dorsal fin.

Source: https://www.dailymail.co.uk/home/article-11769769/Action-plan-Ciar-Byrnes-essential-jobs-garden-week.html?ns_mchannel=rss&ns_campaign=1490&ito=1490

Gov. Gruesome was born with a silver spoon in his posterior, dorsal, orifice who believes he is a kings patrician who can demand that you do everything he pronounces.

Source: http://capoliticalreview.com/top-stories/california-governor-signs-law-barring-schoolbook-bans-based-on-racial-gender-teachings/

Researchers immediately knew her situation wasn’t good when they saw the unnatural “S” curve in Moon’s spine, from her dorsal fin to her fluke.

Source: https://bigislandnow.com/2023/01/16/what-happened-to-moon-the-injured-humpback-whale-hasn%ca%bbt-been-seen-in-weeks/

The really big ones had dorsal fins about one and a half metres long,” he said.

Source: https://the-riotact.com/watch-as-anglers-encounter-a-huge-pod-of-rare-killer-whales-off-batemans-bay/688008

You can discern an electric eel from a true eel by its missing dorsal fin, its ability to breathe air and its tendency to lay eggs in freshwater rather than saltwater.

Source: https://www.discovermagazine.com/planet-earth/10-animal-names-that-have-you-fooled