The fins on a fish

If you position a human and a fish so their skeletons align – for example, with the person performing the plank or swimming – then many of the fins on a fish can directly correspond with parts of a human being.

Image of fins on a fish and how comparisons can be made to the human body

The only other ones are the tail fin, which is obvious, and the dorsal fin, which makes a very odd and memorable image:

Mnemonic depicting the dorsal fin of a fish

Imagine on the top of the fish a Door Sail (Dorsal) instead of a fin.

Annotated image of front and side view of fins on a fish