RED ALGA

Last week I said that sometimes I find organisms washed up on the beach so strange that I can't even say whether they are plants or animals. That's nearly the case with one of the most commonly encountered things. This abundant item is a twiggy, much- branched, orange-red, more-or-less hand-sized article covered with short, blunt tubercles. Often its main stem bears white, stony fragments at its base, which I assume to be bits of the underwater coral reef from which it was torn. The item's stems, which have the consistency of very tough gelatin, barely can be snapped apart by vigorously applying a thumbnail. My friend Cotting White has sent me the picture of it shown below, taken on a Yucatan beach:

On the internet I can find pictures of a red alga of the genus Gymnogongrus seeming to match the organism. However, the matched picture is from the Pacific so I'm hesitant to say it's the same as what I'm finding here. However, a good number of oceanic plants and animals are "pantropical" -- found worldwide in tropical seas -- so this alga indeed might possibly occur in the Pacific as well.

In fact, when you reflect that our tropical waters seem in every respect identical to all other tropical waters, you wonder what's to keep all organisms such as the sea turtles mentioned last week from being pantropical. However the website linked to in that article clearly showed that some sea turtles are pantropical while others aren't. Clearly, the oceans are delimited with ecological barriers or historical events that aren't immediately obvious.

I Googled up the above Gymnopongrus picture by guessing that the thing I was finding was an alga, and using the keywords "alga, red, tropical." What a wonderful thing Google's "image search" feature is for itinerate naturalists!

Still, I'm not saying much by claiming to have found sprigs of red alga. About 6,000 red-alga species exist, of which only some 200 are found in freshwater.

The red algae comprise a taxonomic unit, the Rhodophyta. They come in every form from tiny orbs to large, leafy seaweeds, to coral-like "calcified coraline algae." Probably the best-known red alga is Porphyra, the so-called Red Seaweed cultured as food in Japan. Algae bear no flowers. Their reproduction is based on sperm flowing through water to reach eggs.

You can see several kinds of red algae and read college notes about their forms and life cycles at http://www.jochemnet.de/fiu/bot4404/BOT4404_23.html.