I think red algae is a beautiful marine plant. Red algae are red because of the presence of the pigment phycoerythrin; this pigment reflects red light and absorbs blue light. Because blue light penetrates water to a greater depth than light of longer wavelengths, these pigments allow red algae to photosynthesize and live at somewhat greater depths than most other “algae”. Some rhodophytes have very little phycoerythrin, and may appear green or bluish from the chlorophyll and other pigments present in them.
In Asia, rhodophytes are important sources of food, such as nori. The high vitamin and protein content of this food makes it attractive, as does the relative simplicity of cultivation, which began in Japan more than 300 years ago.
Some rhodophytes are also important in the formation of tropical reefs, an activity with which they have been involved for millions of years; in some Pacific atolls, red algae have contributed far more to reef structure than other organisms, even more than corals. These reef-building rhodophytes are called coralline algae, because they secrete a hard shell of carbonate around themselves, in much the same way that corals do.
Algae That Cause Red Tide Found Off Maine Coast. This Bangor Daily News article provides general information about red tide in Maine and efforts being done to track the harmful algal bloom (HAB) events. There are four major red tide causing algae in Maine: Alexandrium, Dinophysis, Prorocentrum and Pseudonitzschia. These algae can cause serious health problems in humans and other marine animals. The area is monitored for sunlight and nutrient concentrations that may lead to red tide events. (http://serc.carleton.edu/microbelife/topics/redtide/general.html)
Now isn’t that interesting? Pretty plant- causes some trouble.