The following sub-sections in the drop down menu will explain various aspects of coral ecology. It is important to gain an understanding of these aspects in order to fully appreciate how easily these organisms are affected by the smallest of changes in their surroundings:

  1. Reef Formation and Longevity
  2. Distribution
  3. Limitations to Distribution
  4. Feeding

Taxonomy and Structure

Corals are members of the phylum Cnidaria, of which four major classes are known. Found in the class Anthozoa, are the true corals, anemones and sea pens, while the class Hydrozoa, includes siphonophores, hydroids and fire corals (Cairns 2001).

6 common reef building Scleractinians of the deep sea

Fig.2. the 6 common reef building Scleractinians of the deep, top left to right a-c and bottom left to right d-f.

CWCs can further be split up into the five taxa that contribute “significantly to cold-water habitats by providing reef frameworks or other structural habitats” (Roberts et al. 2009): Scleractinia, or stony corals, are the only order to include reef forming species in the deep sea (Cairns 2001). 711 species are azooxanthellates (Roberts et al. 2009), 672 of which thrive in seas >50m deep, including the abyssal depths (4000m-7000m). Further more there are 17 known structure forming Scleractinians , 6 being the most dominant and therefore the most important in research (Freiwald et al. 2004):¬† Lophelia pertusa, Madrepora oculata, Enallopsammia¬†profunda, Goniocorella dumosa, Solenosmilia variabilis and Oculina varicosa (figure 2a-f). Octocorallia (soft corals) a subclass of the Anthozoa. The order Antipatharia (black corals, Figure 3a) the majority of which occur in the deep ocean recorded as far down as 8600m (Freiwald et al. 2004). Zoanthidae (gold corals) the majority of 200 species are soft-bodied and comprise one genus (Gerardia) in one family (Gerardiidae) and the family Stylasteridae or lace corals (figure 3b Corallium secundum).

Two types of coral, black coral and precious coral from Hawaii

Fig.3.(a) 50cm high black coral colony. (b) Precious coral in Hawaii. (Freiwald et al. 2004)

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