We all steal a curious glance at commemorative stamps on letters in our post box, but stamp collectors (known as philatelists!) often target stamps around a theme—like dogs, or cars, or federal duck stamps—for their collections.

In 1960, oceanographer and Professor K.O. Emery of USC published a short paper on “thematic philately” called “Oceanography on a postage stamp”. He heralded the multitude of stamps that portray geological, physical, biological, and economic aspects of oceanography with their dizzying array of fishes, ships, and coastal features. But Emery ended his paper noting the dearth of oceanographic stamps that could show more “interesting designs” like icebergs, coral reefs, kelp, and diatoms!

Along with my colleague Mike Wynne at University of Michigan, we collaborated on a fun article (see link) to overcome that last shortcoming that Emery noted by assembling and reporting on all thirty-five stamps in the world that have portrayed microscopic algae. Emery was right, our oldest algae stamp was from 1963 and issued by South Georgia as part of a 16 stamp set on the southern ocean foodweb. At the base of the foodweb (and on the cheapest stamp) was krill and their prey—diatoms!

Ocean food webs and their microalgae have featured prominently on stamps from Finland and the British, French Southern, and Australian Antarctic Territories. The US has yet to offer up its first stamp commemorating microalgae, but other microalgae stamps have come from around the world—Tonga, Macedonia, Greenland, Wallis and Fortuna, Germany, the Isle of Man, and Monaco.

Diatoms have been the most commonly portrayed microalgae—their shape, symmetry, beauty, and ecological importance are hard to compete with. Dinoflagellates, including the famed bioluminescent Noctiluca, have been the centerpiece of at least five stamps and included with other algae to illustrate ocean plankton diversity. Our oldest algae, the cyanobacteria, have been shown on three stamps including Canada’s 1990 portrayal of stromatolites—fossils formed billions of years ago by the first photosynthetic organisms on earth.

Green algae, charophytes, silicoflagellates, and coccolithophores have made appearances only once on stamps. Other “minor” algal groups (euglenoids, chrysophytes, prasinophytes, haptophytes, xanthophytes, prymnesiophytes, cryptomonads, …) have yet to break into the philatelic majors. But the thirty-five “interesting designs” that Wynne and Edlund pooled from their stamp collections offer a colorful and accessible way for everyone to see that algae from around the world come in all shapes and sizes, are stunning in their microscopic detail, and form the base of our marine and aquatic food webs on which we are so dependent.