Coralline red alga from Hawaii, SEM

Coloured scanning electron micrograph (SEM) of coralline red alga (branched type) from Hawaii. This is the mineralized calcium carbonate surface cell layer (epithelial layer) of a geniculate coralline alga (species unknown) from a marine environment. The thallus is hard because of calcareous (mineralized calcium carbonate) deposits contained within the cell walls. Geniculate coralline algae are branching, tree-like plants which are attached to the substratum by crustose or calcified, root-like holdfasts. The plants are flexible by having non-calcified regions (genicula) separate by longer calcified sections (intergenicula). Coralline algae are widespread in all of the world's oceans. Many are epiphytic or epizoic, and some are even parasitic on other coralline algae. Coralline algae play an important role in the ecology of coral reefs. Magnification: x800 when shortest axis printed at 25 millimetres.