All about corals! by Emily

After spending 3 months in the Seychelles learning about corals, to survey the comeback of the reefs following the mass coral bleaching event which happened in 1997-1998, I have decided to share my knowledge of these fascinating and mesmerising animals!

Each week I am going to write about a different aspect of corals specialising in corals of the Indian Ocean.


This week I am starting off with the big question:

What is a coral?

  • Coral generally refers to reef building corals, hard corals because of their limestone skeletons.
  • French biologist J.A. de Peysonell proved in 1753 that corals were animals and not plants
  • They are often mistaken for plants due to their attachment to the substrate, apparent lack of independent movement and their superficial resemblance to flora.
  • It was the discovery of zooxanthellae (pronounced zoo-zan-thely), which are symbiotic cells and are found living in the flesh of corals and other reef animals, which determined they were in fact animals and not plants.
  • All corals are classified under the Phylum Cnidaria
  • However it is not only hard (limestone skeleton) corals in the phylum, you can also find Sea Fans, Sea Whips, Anemones, Black Corals, Soft Corals, Jelly Fish, Hydroids, Zoanthids, and Corallimorphs.
  • The common features between these are:
    • Cup shaped body
    • Single central opening (gastrovascular cavity) which asks as both mouth and anus
    • Radial symmetry
    • Ring of tentacles surrounding mouth of each polyp
    • Tentacles are covered with stinging cells (nematocysts) used for capturing prey and for defence 
  • There are 8 different  coral lifeforms (shape in which a coral grows)
  • Some coral genre and species grow in only one lifeform, whereas other grow in many varieties
  • Some lifeforms (e.g. Massive) are more resilient than others (e.g. Branching) to wave action and turbulent conditions.
  • The life form recorded should be the one that best describes the whole colony.
  • There are 2 categories in which coral lifeforms are sorted: Acopora and Non-Acopora
    • Acopora: Branching, Tabulate, Encrusting, Submassive, Digitate
    • Non-Acopora: Branching, Foliose, Encrusting, Submassive, Massive, Mushroom


Next week I will be delving further into coral genre and families!! 


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