Successful symbiosis - Carijoa octocoral #marineexplorer by John Turnbull
Via Flickr:
The orange stem of carijoa is actually a coating of encrusting sponge which lives in a symbiotic relationship with the coral. It is thought that the toxic sponge protects the coral’s stem from predators, and in return the coral provides a home for the sponge. This is a very successful relationship - if this is C. riisei, it is endemic to the western Atlantic and has spread throughout the Atlantic and Pacific as an invasive species. Bare Island

Check out these yellow zoanthids! Zoanthids are invertebrates related to reef-building corals and sea anemones. 

These were spotted colonizing the base of a dead golden octocoral in the deep waters of National Marine Sanctuary of American Samoa! 

(Photo courtesy of the NOAA Office of Ocean Exploration and Research, 2017 American Samoa) 

Blue Coral (Heliopora coerulea)

The only species in the family Helioporidae, Heliopora coreulea is an interesting species of Octocoral that is widely distributed throughout the Indo-Pacific. H. coerulea is unusual as it is the only species of Octocoral that is known to produce a “massive skeleton”, the skeleton that H. coerulea produces is formed of aragonite, the same substance stony corals build their skeletons out of. The polyps of blue coral live in tubes within the skeleton and are connected by a thin layer of tissue.

Currently Heliopora coerulea is listed as Vulnerable and likely faces threats from the same reasons many other coral reefs (and species) are threatened by.


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Image: Haplochromis


Spinnaker Anemone (Korsaranthus natalensis)

Also known as the candy-striped anemone, the spinnaker anemone is a species of Actiniid anemone which is endemic to the South African coast, where it occurs from False Bay to Durban. Spinnaker anemones are noted for being partly motile, as they use their parachute like disc to “sail” to different locations to prey on octocorals. 


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Image(s): Seascapeza

Briareum violaceum

…sometimes known as the “star polyp”, Briareum violaceum is a species of Briareid soft octocoral which can be encountered throughout the Indo-Pacific. Like other  corals B. violaceum is partially predatory and will feed on passing zooplankton which it dispatches with its stinging nematocysts. Briareum violaceum is commonly preyed upon by nudibranchs, especially Phyllodesmium briareum which has evolved to mimic B. violaceum.


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Image: Heike Wägele & Annette Klussmann-Kolb