All Caulerpa species can be recognized from the growth of the horizontial cylintrical runners (rhizomes) that they attach to rocks, sand and substrate beds with penetrating rootlike hairs (rhizoids). They only use these runners and roots for anchoring themselves in place, deriving their nourishment (nitrates & phosphates) from the water by means of absorbtion through their blades or fronds.
Feather species can be easily identified by the feather-like blades that extend from the branchlets that grow upright from the rhizome (runner) like the C. sertularioides species. C. sertularioides can have either fine cylintrical or elongated needle-shaped blades or thickened blades and branchlets with a thicker rhizome. C. mexicana has straight-edged tightly packed flat blades, C. ashmedii has tightly packed thick rounded blades, while C. taxifolia has loosely packed tapering flat blades. Beware of C. taxifolia varieties. There is a dangerous Mediterraean cloned strain out there that you do not want, and is in fact banded for importation and even possession in many countries around the world.
Grape species are identified by the characteristic miniature round grape-like clusters that form on the branchlets that stem upright from the rhizome of these plants. C. racemosa has very distinctive numerous smaller or larger sized grape-like clusters, while the peltatavariety has spheres that are enlarged, less in number, and are flattened on top.
Another form of Caulerpa are the Razor types like the C. serrulata (Razor Ribbon). They are recognizable because of the razor-like appearance of their blades. Other forms are C. prolifera that look like a smooth-edged sea grass, C. serrulata that resemble rough-edged Sargassum Weed, C. cupressoides that have the appearance of looking like young spears of asparagus, and C. lanuginosa that look similar, but have fine hairs along the rhizome giving it additional strength for growing in sand. The C. paspaloides species grow as a single upright stalk with multiple and various shaped blades extending from the stalk like the compressa and laxa varieties.
Caulerpa spread almost entirely by asexual growth from spores and by fragmentation. A spore producing Caulerpa can often times release such large numbers of spores that it turns the aquarium water a milkly-green color. If this occurs the spores will settle out, be removed by filtration, be eaten or die off in a short period of time. The water becomes clear again, but the spore producing alga can leave behind a white soft tissued husk that should be removed.
Most species grow well under brilliant lighting in a nutrient rich tank environment. Tangs and Pygmy Angelfish are said to be helpful in keeping them cropped to manageable levels, but if they become a nuisance remove as much as possible with thinning by hand, lower the tank nutrients and decrease the lighting levels.
With over a hundred species of Caulerpa found worldwide we cannot cover them all, but we have highlighted some of the most popular saltwater aquarium species for you. Here are a few more image and information resources to help with the identification of Caulerpa found in the Chlorophyta Phylum.
- Chlorophyta photos from Living Reef Images. (Three pages to click through for views of various Caulerpa images and other green algae species.)
