Porolithon pachydermum (calcareous red algae) (San Salvador Island, Bahamas) 1 : 無料・フリー素材/写真
Porolithon pachydermum (calcareous red algae) (San Salvador Island, Bahamas) 1 / James St. John
| ライセンス | クリエイティブ・コモンズ 表示 2.1 |
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| 説明 | Porolithon pachydermum (Foslie, 1904) - "reef cement" (calcareous red algae) on a patch reef in the Bahamas.Rhodophytes are red algae - they are the most common and widespread of marine macroalgae, but they often go unnoticed because of their frequently-dull coloration and nondescript growth forms.Over 7000 species of red algae are known in the Holocene - most of them are marine, plus some freshwater forms. Rhodophytes are known in the fossil record. The oldest reported fossil red algae are from the upper Mesoproterozoic (~1.2 Ga) of northern Canada.Red algae vary in coloration - not all are reddish-colored. Rhodophytes can be red, pink, pale pink, lavender, purple, brownish-red, whitish, and yellowish. Fleshy red algae are usually weed-like to mossy to fuzzy in appearance. Calcareous red algae have skeletons with calcium carbonate (CaCO3 - calcite or aragonite). Calcareous red algae are important reef organisms - they include branching forms and crusts. Upon death, the hard part skeletal components of calcareous red algae become biogenic sediments in reef and peri-reef environments.Porolithon pachydermum is a pinkish to pale-pinkish, calcareous crust that occupies reef crest and near-reef crest facies, where high-energy waves, intense sunlight, and occasional desiccating conditions (from low tides) occur. It has been recognized as a very important reef-building organism. Porolithon crusts frequently have many subcircular openings (see above photo), resulting in a “swiss cheese”-like appearance. These are borings produced by the chiton Choneplax lata (malacos.chez.com/htm/C08G2.HTM) (Mollusca, Polyplacophora).Classification: Rhodophyta, Florideophyceae, Corallinales, CorallinaceaeLocality: patch reef in western French Bay, southwestern San Salvador Island, eastern Bahamas-----------------More info. at:en.wikipedia.org/wiki/Red_algaeanden.wikipedia.org/wiki/Porolithon |
| 撮影日 | 2011-03-21 14:32:43 |
| 撮影者 | James St. John |
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