This Division is known as the Cyanophyta which is why species in this group are often referred to as cyanobacteria. These are primitive organisms with much less complex structures than all the other macroalgae; which is why they are more accurately described as photosynthetic bacteria. They are related to other plants solely by their ability to perform photosynthesis and in fact all plants owe their ability to photosynthesize to the cyanobacteria whose ancestor was engulfed by a eukaryotic cell which gave rise to chloroplasts (the photosynthetic centers in plants). These algae are generally small and inconspicuous and are often very prominent on Hawaiian reefs. The color of these algae can vary from red, purple, brown, green and black and all combinations of these colors. Currently there is not a very accurate census of cyanobacteria found in Hawai’i so it is hard to tell exactly how many species can be seen but there are a few that are fairly commonly seen.
Lyngbya majuscula
This species is one of the most commonly encountered on all Hawaiian reef flats. It forms a coarse, blackish tuft that can grow on a variety of substrata. It produces a toxin that when touched can cause a rash called “swimmers itch”. It is most easily recognized by its long hair-like structure and can be attached to rock or as an epiphyte on larger algae where it floats back and forth in the water with wave action.
Symploca hynoides
This species is generally found on reef flats in shallow water. It is a filamentous cyanobateria that forms colonies of erect filaments. These tufts have a characteristic wick-like appearance and generally have a firm texture.
Limu Watch 