Photo Synthesis

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Sea fans are among the most beautiful sights seen by divers. Gorgonian sea fans are Cnidarians that build colonies in branching formations that usually are fan-shaped, thus the common name.

Like the Nephtheid soft corals I wrote about recently here on Photo Synthesis, Gorgonians are octocorals: each polyp has eight pinnate tentacles which it uses to capture nutrients suspended in the water column. They are seen most often on reef crests, or jutting out from drop-offs or steep banks in locations where natural currents will sweep plankton and other organic nutrients across the polyps’ tentacles.

Some sea fan species form colonies in a single plane, while others grow their branches in somewhat of a tangle. They come in quite an array of colors, most of which actually are the result of zooxanthellae that live in the structural tissue of the Gorgonian. Beyond giving them attractive coloration, zooxanthellae also produce nutrients through photosynthesis, which benefit the Gorgonians.

By the way, not all Gorgonians form fan-shaped colonies. Some families in this order form long, slender colonies, commonly known as Sea Whips — but we’ll save those for another time. Today I’d like to show you some close-up and macro photos of some Gorgonian sea fan species from several tropical locations around the world to illustrate some of the variability in the morphology of the colonies. (A brief description follows each photo.)

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Above is a sea fan from the genus Melithaea, with its polyps open for feeding. The branches of sea fans in this genus tend to intertwine. This one was photographed at Bunaken Island, Indonesia.

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The next sea fan, Acabaria sp., forms a fragile looking net-like colony. There are other species in this genus that form denser structures. This one was photographed in the Red Sea, off the coast of the Sinai Peninsula.

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The above macro image shows a section of Subergorgia hicksoni, a species widely distributed throughout the Red Sea. This sea fan species is not so beautifully colored, but the colonies grow to an impressive size, very often measuring more than a meter in width. The fans are relatively flat, or gently curving. This species is dominant on many deep reefs in the Red Sea, whereas Acabaria spp. seem to prefer shallower depths.

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This purplish sea fan is Gorgonia ventalina, photographed in the Cayman Islands. It forms a tight mesh, and grows in a single plane. G. ventalina is very common throughout the Caribbean Sea. In fact, the sight of this purple fan is almost a hallmark of Caribbean reefs. It tends to live in on patch reefs in relatively shallow water, so it is seen very frequently by divers and snorkelers.

The final photo, below, shows an entire colony of G. ventalina, photographed at West Caicos, in the Turks and Caicos Islands.

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Comments

  1. #1 Virginia
    August 21, 2009

    Gorgeous! I am really enjoying your posts this month. There’s a lot of serious design fodder in this post – thanks for the inspiration.

  2. #2 Alex
    August 21, 2009

    Wow, those are stunning.

  3. #3 B. N. Sullivan
    August 21, 2009

    Virginia, thanks. I’m glad to know you’re enjoying these images. Not to sound corny, but I think ol’ Mother Nature has the most interesting design ideas around. Unfortunately most people don’t get to see very many of the ones that are under the surface of the sea.

    Alex, thank you very much.

  4. #4 Greg Peterson
    August 24, 2009

    Lovely, extraordinary images. It’s been years since I’ve seen such fans in person; the wonderful photography took me back in my mind to a singular adventure of many years ago…one I am now more eager than ever to recapture sometime. Thanks so much!

  5. #5 B. N. Sullivan
    August 25, 2009

    Thank you, Greg. If these images have inspired you to get back into the water to see some sea fans in person again, then I feel gratified for having posted them.

  6. #6 avnish chauhan
    August 27, 2009

    the pictures are wonderful, indeed encourages to conserve our extremly rich biodiversity

  7. #7 B. N. Sullivan
    August 27, 2009

    Thank you, Avnish.

  8. #8 Anon
    August 27, 2009

    “Gorgonia”–”gorgon” is the Greek equivalent of “mermaid”–is there a story behind this name?

  9. #9 B. N. Sullivan
    August 27, 2009

    @ Anon – Actually (if I remember correctly), the Gorgons in Greek mythology were female entities that had snakes for hair. Medusa was one of the Gorgons. This is only a guess, but perhaps the Gorgonian corals, which include sea whips as well as sea fans, were so named because their branches resembled ‘snakes for hair’? Compared to sea fans, the gross morphology of sea whips is much more suggestive of ‘snakes for hair’.

    (If some coral taxonomist out there would like to chime in on the origin of the name Gorgonian, please do so.)

  10. #10 Anon
    August 28, 2009

    The snake-haired sweeties are not necessarily *not* mermaids–a dear friend, a Greek writer, once chastised me that “Greeks do not do Disney”; their mermaids are not cute or romantic, but monstrous. “Gorgona” in modern Greek translates to “mermaid”, but the cultural difference is why I used the phrase “Greek equivalent”.

    Alas, my dictionary suggests a less fanciful explanation than mermaids fanning themselves. Gorgonia, it says, is from the Latin, not the Greek. Gorgon or Gorgo-, in Latin, simply refers to coral. Given Latin’s penchant for borrowing from Greek, one possibility is that coral is seen as being turned to stone (which, I suppose, in a sense, it is) as were any mortals who looked at a gorgon.

    A fun bit of searching, though–thank you for the beautiful and inspiring photos!

  11. #11 Jasbina Misir
    August 31, 2009

    I really enjoyed that, as always.
    The discussion about the etymology of “Gorgonia”.

  12. #12 megadosya
    May 8, 2010

    I really enjoyed that, as always.
    The discussion about the etymology of “Gorgonia”.

    yes thanks..nice post

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    February 26, 2011

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  14. #14 tütünex
    February 26, 2011

    The snake-haired sweeties are not necessarily *not* mermaids–a dear friend, a Greek writer, once chastised me that “Greeks do not do Disney”; their mermaids are not cute or romantic, but monstrous. “Gorgona” in modern Greek translates to “mermaid”, but the cultural difference is why I used the phrase “Greek equivalent”.

    Alas, my dictionary suggests a less fanciful explanation than mermaids fanning themselves. Gorgonia, it says, is from the Latin, not the Greek. Gorgon or Gorgo-, in Latin, simply refers to coral. Given Latin’s penchant for borrowing from Greek, one possibility is that coral is seen as being turned to stone (which, I suppose, in a sense, it is) as were any mortals who looked at a gorgon.

    A fun bit of searching, though–thank you for the beautiful and inspiring photos!

  15. #15 orjin krem
    April 25, 2011

    The snake-haired sweeties are not necessarily *not* mermaids–a dear friend, a Greek writer, once chastised me that “Greeks do not do Disney”; their mermaids are not cute or romantic, but monstrous. “Gorgona” in modern Greek translates to “mermaid”, but the cultural difference is why I used the phrase “Greek equivalent”.

    Alas, my dictionary suggests a less fanciful explanation than mermaids fanning themselves. Gorgonia, it says, is from the Latin, not the Greek. Gorgon or Gorgo-, in Latin, simply refers to coral. Given Latin’s penchant for borrowing from Greek, one possibility is that coral is seen as being turned to stone (which, I suppose, in a sense, it is) as were any mortals who looked at a gorgon.

    A fun bit of searching, though–thank you for the beautiful and inspiring photos!

  16. #16 iş ilanları
    June 27, 2011

    Alas, my dictionary suggests a less fanciful explanation than mermaids fanning themselves. Gorgonia, it says, is from the Latin, not the Greek. Gorgon or Gorgo-, in Latin, simply refers to coral. Given Latin’s penchant for borrowing from Greek, one possibility is that coral is seen as being turned to stone (which, I suppose, in a sense, it is) as were any mortals who looked at a gorgon.

  17. #17 tadilat
    November 12, 2011

    I really enjoyed that, as always.
    The discussion about the etymology of “Gorgonia”.

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