Jellyfish (Porpita Porpita) drawing (1800s) by Ernst Haeckel Poster
Porpita porpita, or blue button, is a marine organism consisting of a colony of hydroids found in tropical and sub-tropical waters of the Pacific, Atlantic, and Indian oceans. Although it is superficially similar to a jellyfish, each apparent individual is actually a colony of hydrozoan polyps. The blue button is a Chondrophore, which is a group of cnidarians that also includes Velella and Porpema. The chondrophores are similar to the better-known siphonophores, which includes the Portuguese man o' war, or Physalia physalis.
Ernst Haeckel was a German zoologist, naturalist, philosopher, physician, professor, marine biologist, and artist who discovered, described and named thousands of new species, mapped a genealogical tree relating all life forms, and coined many terms in biology, including ecology, phylum, phylogeny, and Protista. The published artwork of Haeckel includes over 100 detailed, multi-colour illustrations of animals and sea creatures.