My Stylophora has crabs

Discussion in 'Invertebrates' started by Manic, 1 Oct 2009.

  1. Manic

    Manic Moderator

    Joined:
    12 Mar 2009
    Posts:
    3,313
    Likes Received:
    58
    Location:
    Johannesburg, Edenvale
    Hey everyone,

    So like the heading says, I recently purchaced a Stylophora Pistillata. As I opened the packet, I noticed two crabs living in the coral. One is big and the other is really small. Just wanted to know if they are safe or not. Here's the pic:

    [​IMG]

    Is it an acro crab or something completely different. I've tried to google it but cant find much.
     
  2. AdS Guest




    to hide all adverts.
  3. vladfragdit

    vladfragdit Fragd.it Blogger

    Joined:
    12 May 2009
    Posts:
    34
    Likes Received:
    0
    Location:
    Toronto, Canada
    It doesn't look like it has a giant claw.. so its a good crab. What about the other one?
     
  4. Manic

    Manic Thread Starter Moderator

    Joined:
    12 Mar 2009
    Posts:
    3,313
    Likes Received:
    58
    Location:
    Johannesburg, Edenvale
    The other one looks exactly the same just smaller...
     
  5. Afsal

    Afsal

    Joined:
    7 May 2007
    Posts:
    2,319
    Likes Received:
    23
    Location:
    Dbn,Kzn
    they "good" crabs .....
     
  6. jean19

    jean19

    Joined:
    21 Sep 2009
    Posts:
    71
    Likes Received:
    0
    Location:
    france .
    better him than you !!!:wave2:(i couldn't resist )
     
  7. vladfragdit

    vladfragdit Fragd.it Blogger

    Joined:
    12 May 2009
    Posts:
    34
    Likes Received:
    0
    Location:
    Toronto, Canada
    Then they are fine. :)
     
  8. seank

    seank

    Joined:
    24 May 2007
    Posts:
    11,984
    Likes Received:
    119
    Location:
    North of Durban and South of Mozambique
    These crabs are fine. If you remove them from the coral, nothing will "clean"the coral- and this I have seen 1st hand. That is their job. I had many of these corals in the past and all of them have/had these crabs inside them.
     
  9. Manic

    Manic Thread Starter Moderator

    Joined:
    12 Mar 2009
    Posts:
    3,313
    Likes Received:
    58
    Location:
    Johannesburg, Edenvale
    Awesome, just read a study they did on these crabs and according to their results these crabs can actually make the growth rate of the coral increase...:)
     
  10. seank

    seank

    Joined:
    24 May 2007
    Posts:
    11,984
    Likes Received:
    119
    Location:
    North of Durban and South of Mozambique
    Here you go:

    [​IMG]

    [​IMG]
     
  11. Tony

    Tony

    Joined:
    23 Aug 2008
    Posts:
    4,093
    Likes Received:
    68
    Location:
    Honeydew, Johannesburg
    Those red crabs are fine. It's the hairy ones that chow the corals
     
  12. seank

    seank

    Joined:
    24 May 2007
    Posts:
    11,984
    Likes Received:
    119
    Location:
    North of Durban and South of Mozambique
    commensal crab (Trapezia cymodoce)

    This shot shows a commensal crab (Trapezia cymodoce) coming out of its host coral (Pocillopora damicornis) to attack the arm of an invading Crown of Thorns Starfish (Acanthaster planci).


    [​IMG]


    The crab Trapezia cymodoce shown in the "Image of the Month" is one such infaunal symbiont.
    It is found throughout the Indo-Pacific, but only resides within corals from the family Pocilloporidae, which includes the common species Pocillopora damicornis (shown in the image), Seriatopora hystrix, and Stylophora pistillata.

    Like most other coral reef organisms, T.cymodoce has an obligate period of larval development in the open ocean before recruiting back to the reef.
    Post-larval crabs usually settle individually into small bushes of coral, while larger corals usually house a heterosexual breeding pair of adult crabs.
    Very large coral colonies may house more than one pair. Crabs do occasionally move short distances between coral colonies, but only at night so as to minimise the predation risk.

    It is fairly clear that the crab benefits from living inside the coral. It feeds on mucous secreted by the coral, and also actively feeds on coral tissue, scratching and probing at the polyps with its sharp walking legs.
    Obviously, the crab also obtains a great deal of protection from predators by staying within the narrow spaces between the arms of the coral colony.

    But what are the benefits to the coral? If the crab is in fact eating coral tissue, its actions could be more akin to a parasite than a symbiont! Yet field studies show that corals with crabs grow faster and suffer lower mortality than those without crabs.
    This gives a clue to the answer - the crabs are active defenders of their home, reducing the damage to the colony from corallivores such as butterflyfish and Crown of Thorns starfish (COTS).
    As shown in the "Image of the month", when a COTS approaches a Pocilloporid coral, the crabs immediately rush forth and nip the tube feet and spines of the starfish with their chelae.

    This defence is so effective that, if given a choice, COTS will actively avoid feeding on Pocillopora damicornis in favour of specimens of Acropora which have less aggressive crustacean symbionts. Only when there is little alternative will the starfish resort to feeding on P. damicornis colonies. Indeed, where P. damicornis is abundant, it may form natural barriers to COTS and create predation refuges for other species of corals, thereby helping to maintain coral biodiversity on COTS affected reefs.

    So, the crab Trapezia cymodoce living in the coral Pocillopora damicornis is another good example of the many symbiotic partnerships found on coral reefs, where both members of the partnership gain some benefit from the relationship. As a final word, just to give you some idea of the complexity and diversity of the reef environment via the microcosm of coral symbionts, we know there are more than 10 different species of crabs in the genus Trapezia, plus another genus of crabs (Tetralia), plus a few species of Alpheid shrimps, plus at least 6 species of goby, all of which live in symbiotic relationships with hard corals! Indeed, a large colony of Pocillopora damicornis usually has a whole micro-community of crabs, shrimps, and gobies inside it!
     
  13. Mekaeel

    Mekaeel Moderator MASA Contributor

    Joined:
    8 May 2007
    Posts:
    24,229
    Likes Received:
    127
    Location:
    Point Waterfront Durban
    He is a friendly. They live in a symbiotic relationship. :)
    Good article there Sean!
     
Recent Posts

Loading...
Similar Threads - Stylophora crabs Forum Date
[wtd] Stylophora frags durban Wanted 25 Apr 2016
Stylophora coral wanted Wanted 12 Jun 2012
[wtd] Hermit Crabs and Turbo Snails Wanted 25 Sep 2016
[wtd] Emerald crabs/ red Mithrax crabs Wanted 16 Jul 2016
BTA hosting clowns and crabs? Anemone's 11 Jun 2016
Sumped crabs General Discussions and Advice 27 Jan 2016
blue hermit crabs Beginner Discussions 4 Nov 2015