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Indonesia Underwater: Algae and Vascular Plants

To: Macro-life Indonesia Long VersionShort Version,

Related FAQs: Indonesian Biotopes

Bob Fenner, WetWebMedia.com

A patch of Halimeda in Bunaken

'What's It All About, Algae'? 

            Looking for a quick course on Phycology (algology if you're from the Old World)?  Indonesia's got the goods on all but the giant kelps. Here's a short picture story on what to expect: 

Greens (Division Chlorophyta), what most folks think of as Algae'¦ Important as foods, hiding places (you'll be richly rewarded here for looking closely, then even more closely!). Pictured below: a healthy bunch of Caulerpa racemosa, C. serrulata, C. webbiana just to mention three of the same genus found here.

More Specifically:

Caulerpa racemosa, Green Grape Algae.

Chlorodesmis fastigiata, Turtle Weed... common in the wild in reef places, especially where damaged or polluted.


Halimeda species are crusty, calcified algae that look like a bunch of small platelets strung together in a chain.

Here's a cactus-like articulated algae, Halimeda discoidea... a favorite haunt of the like-named Halimeda Ghost Pipefish,  Solenostomus armatus (right), some camouflage job now!

Tydemania expeditionis Weber-van Bosse 1901, which I like to call "Dread-Locks Algae", for obvious reasons.

Valonia (Ventricaria) ventricosa is often noted as the "largest single-celled alga" reaching a hen's egg in size... but it is actually a multinucleate vesicle held down by attachment rhizoids. Dictyosphaeria species,  in the same group, Order Siphonales, are similar with polygonal vesicles, versus lenticular ones for Valonia.  Mithrax/Emerald Green Crabs may eat these. 

Red Algae, the Rhodophyta of Indo.:

Reds can be leaf-like, filamentous, or encrusting as hard pieces or flat sheets. Some species are of extreme importance in reef-building, serving to hold living and non-living components together in all weather through eons. Shown: Peyssonniela and Rhodymenia sp.

Galaxaura sp.  A less than red admittedly specimen in S. Sulawesi.


Laurencia sp. Here in S. Sulawesi.

Brown Algae, The Phaeophyes:

Dictyota species, cold to cool to tropical species (plural). Some examples of colonies, the second covered in bryozoans.

Lobophora variegata, Encrusting Fan-Leaf Algae. Fan-shaped blades that encrust rock. Occur in brown, red, green colors

Real/Vascular Plants:

    Yes, there are "true" plants in the sea... most known as "Seagrasses". Unlike the lowly algae, plants have functional roots, leaves, transporting tubules (xylem, phloem), flowers (seasonally) and seeds... Here's a common one for our area, the aptly-named Paddle Weed, Halophila ovalis.

Thalassia hemprichii, Seagrass. Here in S. Sulawesi on the top of the reef flat and crest.

Oh, and Blue Green "Algae", Actually Bacteria:

Usually black to dark blue and always slimy to the touch, Blue Green Algae, aka Cyanobacteria are sheets, slimes, threads and more of ancient organisms... Mostly found in areas that have been heavily damaged... by anchoring, siltation, chemical pollution.


Bibliography/Further Reference:


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