With fossil records dating back to the mid-protozoic period, Red algae or Rhodophyta is the most advanced division of algae. Red algae however falls from this most advanced status in one notable respect – its inhibited means of mobility. Unlike brown algae, which has the ability to move or swim freely in some of its life stages, red algae lacks flagella or centrides and is able to move only in an amebic fashion.
Red algae has one of the most complicated life histories among algae divisions. Ranging between the tropics and temperate cold-water regions, there are 2500-6000 species of red algae in 670 marine genera. Most of these species are economically significant, particularly in the manufacturing of foods and gels. In addition red algae help to provide habitats for other marine organisms, as well as maintaining coral reefs.
The structure of Rhodaphyta – Mazzealla splendens or iridescent seaweed algae – is comprised of three parts: the holdfast, the stipe and the blades. The holdfast is responsible for attaching the algae to a surface. After the fronds die back in the winter, in the spring the holdfast is able to sprout a new main frond from which several smaller ones grow, thus making it perennial. The smallest and most disproportionate feature of iridescent seaweed is the stipe or stalk. The largest structural features are the fronds – flat broad blades with ruffled margins growing in lengths to 8 inches long.
When young, iridescent seaweed is a bluish color which turns redder as it ages.
These colors are produced by the pigments phycocyanin and phycoerythrin respectively. Because of the presence of these pigments, iridescent seaweed is able to absorb red, blue and green light. This ability to capture longer wavelengths allows it to grow at greater depths than other algae (up to 20 meters). Sheets of cells with numerous intertwined filaments characterize the unique intercellular structure of iridescent seaweed. This structure gives them a rubbery, springy feeling. The multiple layers of cuticle cell walls produce its characteristic iridescence. It has no vascular system but instead delivers needed nourishment and eliminates waste through the process of direct diffusion through the cell walls.
Unlike other divisions of algae, Rhodopyta has a triphasic reproductive life cycle., occurring in three life history phases: the gametophyte, the carposporphyte and tetrasporophyte. Reproduction has been called “a division which has a very strange repertoire of sexual antics†which is believed to have evolved to promote greater reproductive output. Within its complex life cycle, each plant is designed to alternate between being male and female. The blades are covered by sporangia which convert to the spore (female) phase in summer and to the gamete (male) phase in winter. Both these male and female reproductive elements are morphologically similar, that is alike in structure. As in human reproduction with the sperm and egg, spores and gametes contain one half of the genetic code for the species..
The blades are tasked with having to produce all means of sustenance for the algae due to the fact the holdfast isn’t a true root. The fronds not only fulfill their primary function of photosynthesis but must also absorb minerals and carbon dioxide directly from the water. Through the process of photosynthesis, light is absorbed by chlorophyll and is then used to convert raw materials into sugars. As in green land plants, these sugars are stored in the starch called “floridian†that is found in the cytoplasm.
Flourishing in temperate West Coast waters, iridescent seaweed attaches itself to the rocky coastline from Alaska to Mexico. This seaweed grows in mostly upright clusters in extensive beds forming noticeable bands or zones. With proper sustenance and water conditions, it can grow, as said earlier, at depths of up to 20 meters.
Rhodophyta is not only the most advanced division of algae but also the most beneficial to humans and and other animals, providing a rich source of minerals and vitamins to a broad spectrum of animal kingdoms, from bacteria to humans. The substance agar extracted from seaweed not only helps to give a smooth texture to manufactured food products but also serves as the primary culture medium for growing bacteria in a controlled environment. Similar to agar is carrageen, another derivative that helps retain moisture. Carrageen is also used in a number of manufactured products – for example paper, spark plugs, toothpaste, face creams, chocolate milk, etc. Another extract of iridescent seaweed is algin which is used in buttons, paints and soaps.
Despite occupying a humble position in the hierarchy of kingdoms, Rhodophyta is no less important than more advanced life forms. Without its contribution to the ecosystem, none of the higher kingdoms could survive, and life as we know it would not exist. Because of the extensive use of red algae, its over-harvesting is now endangering the environment. Research is currently underway to commercially grow iridescent seaweed as well as other similar algae.
Tags: