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Echinaster callosus

Marenzeller, 1895

Ryanskiy Andrey Acoel flatworms (Waminoa sp) on the sea star Echinaster callosus? ID flatworms Please!

Ron Silver Your ID is correct - Waminoa sp.

Ryanskiy Andrey Thank you, Ron Silver, I asked to check ID because I never saw this "sea star acoel flatworm" before, only on corals, and much less in size. Not in the books, I think

Boomer William Wing Ryanskiy Andrey, these flat forms are often nicknamed "Red Pests". High population densities can cause tissue damage in corals. They really do not feed on them but populate corals to pick up light, as they, like corals, contain "Zoozanthella " endosymbionts Dinoflaggelates. The acoles use the byproducts and some of the sugars produced as food, just like corals. They can be a big issue in captive and aquacultured corals, but not as devastating as "AEFW", Acropora Eating Flat Worms" of the genus Amakusaplana sp. and usually A. acroporae. More than likely these acoles are using the "warts" of the starfish, similar to what they do on a coral, where they drape themselves over a rounded / bulbous tissue usually to get the best surface area that lets them pick up the most light.

Lee Goldman Boomer William Wing I understood that Waminoa don't actually feed on the tissue of corals but on the mucus. Like corals (and most other zooxanthellate species) their algae only provides some of their requirements, thus feeding on something else (for these guys, mucus). I just got back from Raja Ampat and was amazed to see many, many soft corals infested by thousands of these worms and many of the largest concentrations in shaded areas (thus not seeking the 'most sunlit environment). Further, they appear to love Plerogyra sinousa, a coral that prefers shade. Please, though definitely correct me if I am wrong in suggesting (I had read it so I am only conveying what I read) that waminoa are not feeding at all on corals. Thanks

Lee Goldman Sorry, to clarify the final sentence of the previous statement: feeding on the mucus, not the tissue itself.

Boomer William Wing Yes Lee Goldman it is believed they do or may feed on the mucus. Many corals produce allot of mucus, especially Acro's, which is shed daily, mostly by currents. Mucus producing in corals is a big tax on their energy buget, especially Acro's. So, feeding on mucus is not a big issue unless there are high population densities that can block coral light, end result issue damage or stripping it away to fast due to high population densities. There is no known photosynthetic coral or polyclad, as far as I know, that can get 100 % of its daily requirements from Zoozanthella, although years ago they thought they could., which I NEVER believed. Yes, thy love Bubble Coral. Many corals grow in the shade so to speak, but are still photosynthetic, unless you are dealing with NPS corals. What these polylads are really doing is not fully understood yet.

Lee Goldman Thanks. So then they actually do seek out corals to feed on them (the mucus) to a larger degree than as substrate on which to gather light. I guess I am interested in their (the worms) agenda which, I believe, is to infest and feed upon the mucus as a primary means of food and use their (the worms) symbiotic algae as a secondary (as I believe even some corals do). In a sense (maybe even a strong sense) these worms are parasitic? Mucus to some degree is a defensive barrier for corals. Further, the worms disrupt the coral/zooxanthellae exposure to sunlight. Thoughts?

Boomer William Wing Those are some good points but more can be added here and your points have been brought up on this issue elsewhere. The pic on this post is a starfish. So, is it feeding off the mucus here or is it really a misguided thought per say ? For example, all theses animals we see them on and there are many, is it really not the mucus per say but more likely actually bacteria on the surface or a combo of each ? Corals are big bacteria eaters for example. Said polyclads also reduce a corals ability to feed on zooplankton and there is evidence in some studies it is a competition between the flat worm and coral who gets the zoo. You may like these Lee :) Tissue loss in corals infested by acoelomorph flatworms (Waminoa sp.) http://download.springer.com/static/pdf/737/art%253A10.1007%252Fs00338-012-0919-7.pdf?auth66=1384403635_881e368490151adb1068488febb57925&ext=.pdf Coral disease prevalence and coral health in the Wakatobi Marine Park, south-east Sulawesi, Indonesia http://carnuk.org/library/Journal%20of%20the%20Marine%20Biological%20Association/Haapkyla%20et%20al.%202007.pdf Epizoic flatworms impair coral feeding: evidence for parasitism http://www.advancedaquarist.com/2012/11/aafeature Epizoic acoelomorph flatworms impair zooplankton feeding by the scleractinian coral Galaxea fascicularis http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3545264/

Lee Goldman Thanks Boomer William Wing! I definitely do like the links :-)!

Boomer William Wing Lee Goldman I see there was a bad link, fixed it

Ryanskiy Andrey It is like reading detective story about very small world - with gangs of flatworms engaged in kleptoparasitism, stealing tasty Artemia nauplii :)

Lee Goldman Thanks Boomer William Wing. I had the first one but I really enjoyed the others as they were way more in depth. Attached are two photos I took a few weeks ago in Misool (Raja Ampat). Sinularia (soft coral) and Porites (hard coral) were found to have large infestations and on several different reefs in the area.

Lee Goldman The other...

Boomer William Wing I did not think they could be that invasive on a reef but proof is in the pudding. Thanks for the pics. Crap, that is bad as we see them in some aquaria and aquaculture facilities, which are far more pro to densities like this in closed seawater systems.

Lee Goldman Some colonies of Sinularia had infestations that measured in the square meters...

Boomer William Wing Anything odd going on on that reef that is not normal to you ?

Lee Goldman Nothing much. Reefs were pretty healthy otherwise. It was clearly more concentrated on some of the reefs in Misool versus northern Raja (Waigeo, Dampier Straight).

Ryanskiy Andrey Lee Goldman, I am looking forward to my West Papua trip (Dampier Straight, Kri, 1 week in December 2013). Can you advice smth special to look at in micro world?

Lee Goldman Hi Ryanskiy Andrey. Kri and Mansuar (west of Kri) have some of the best diving in the world. Are you staying on Kir? If so, the house reef will probably provide a lifetime of micro-critter possibilities. Make sure you do spend a bit of time away from the macro lens to enjoy the herds of bumphead parrotfish, sharks, and mantas :-). Of course, if you are diving the area on new or full moon, chances are good you won't have time (or the ability :-)) to stop to search for commensal shrimp on sea stars (for example) :-). Enjoy the ride

Ryanskiy Andrey Thank you, Lee Goldman, I was planning to take fish-eye lense too this time :) I am staying on Kri, December 22-29. It is one week after fool moon (December 17)

Blogie Robillo Is this Echinaster callosus? Spotted it crawling on rubble in 71ft of water at Angel's Cove

Danny Curran I think you are right. Sure looks like it to me.

Blogie Robillo Thanks, Danny!

Bob Whorton Nice up close with their thousands of little feet :)

Animalia (Kingdom)
  Echinodermata (Phylum)
    Asterozoa (Subphylum)
      Asteroidea (Class)
        Spinulosacea (Superorder)
          Spinulosida (Order)
            Echinasteridae (Family)
              Echinaster (Genus)
                Echinaster callosus (Species)
Associated Species