Fig. 1: Micrographs of DDAs taken near Station ALOHA, July 2015, show the major groups of DDAs present in the surface ocean.

a Rhizosolenia sp. are the largest, most abundant, DDA near Station ALOHA and contain Richelia sp. symbionts inside the diatom frustule. b Chaetocerous sp. contain many symbionts attached to the outside of the frustule. c Richelia sp. dislodged from its host. Notice the large heterocyst with the trailing daughter cells. d Hemiaulus sp. also contain the symbionts on the inside. Images: C.L. Follett