The Many Faces of Trichodesmium

Trichodesmium come in a variety of pigments. This species, Trichodesmium tenue,  is salmon pink. (Photo by Annette Hynes, Woods Hole Oceanographic Institution)

Camel-brown-colored Trichodesmium thiebautii is the dominant Trichodesmium species in the North Pacific and North Atlantic Oceans. (Photo by Annette Hynes, Woods Hole Oceanographic Institution)

What's in a name? Trichodesmium pelagicum used to have its own genus: Katagnymene. Once scientists started looking at their DNA, they realized that Katagnymene and Trichodesmium were the same thing. They have curly trichomes (or filaments,) and the little black bars are their "friends," bacteria living in culture with them. (Photo by Annette Hynes, Woods Hole Oceanographic Institution)

Trichodesmium cells are fragile and can pop under pressure. Brick-red Trichodesmium contortum is the linebacker of cyanobacteria with huge, hockey puck-shaped cells. (Photo by Annette Hynes, Woods Hole Oceanographic Institution)

Brick-red Trichodesmium erythraeum is the "lab rat." It survives well in culture and has been the Tricho of choice for lab experiments. (Photo by Annette Hynes, Woods Hole Oceanographic Institution)

Trichodesmium sp. H9-4 is the green sheep of the WHOI culture collection. The cells look like T. thiebautii, the DNA looks like T. tenue, and the sage green coloration looks like nothing else. (Photo by Annette Hynes,Woods Hole Oceanographic Institution)

Filaments of Trichodesmium sp. H9-4 come together to make colonies shaped like puff balls. This strain makes puffs, tufts, and free trichomes all in the same bottle. (Photo by Annette Hynes, Woods Hole Oceanographic Institution)

A puff colony of Trichodesmium thiebautii. Bacteria, copepods, and larvae all hitch a ride on these buoyant mini-oases. (Photo by John Waterbury, Woods Hole Oceanographic Institution)