Author David Starr Jordan (1851–1931)
English: Portuguese Man-of-war Fish, Gobiomorus gronovii. Family Stromateidae
Subject: Portuguese man-of-war
Tag: Fish
Date 1907
Source/Photographer David Starr Jordan (1907) Fishes, New York City, NY: Henry Holt and Company
Source: https://commons.wikimedia.org/wiki/File:FMIB_51928_Portuguese_Man-of-war_Fish,_Gobiomorus_gronovii_Family_Stromateidae.jpeg

The Atlantic Portuguese man o' war (Physalia physalis), also known as the man-of-war, blue bottle, or floating terror, is a marine hydrozoan of the family Physaliidae found in the Atlantic Ocean, as well as the Indian and Pacific Oceans.

The man-of-war fish (Nomeus gronovii) is a species of fish in the family Nomeidae, the driftfish. It is native to the Atlantic, Pacific and Indian Oceans. It is notable for its ability to live within the deadly tentacles of a siphonophore, the Portuguese man o' war, upon whose tentacles and gonads it feeds.