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Marine Animal Encyclopedia

Trichodesmium erythraeum

Individual filamentous colonies of the cyanobacteria Trichodesmium erythaeum are just visible to the naked eye, and these bacteria have traditionally been known as sea sawdust by mariners. Under warm conditions, the bacterium is able to multiply extremely rapidly to create massive blooms that may have such an extent that they are visible from space.

There is a prolific nitrogen-fixing bacterium that harnesses about half of the nitrogen passing through oceanic food chains. The bacteria form in long, multicelled filaments, in which some cells carry out nitrogen fixation, while others are specialized for photosynthesis. These tasks must be separated because the oxygen by-product that results from photosynthesis would interfere with the nitrogen-fixing process, so they cannot both occur in the same cell.

  • Domain Bacteria
  • Size 1–10 mm per colony
  • Distribution Tropical and subtropical seas worldwide