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Siraius nucleola

(Pease, 1860)

Patrik Good Generation X. Thought I'll share this one too. Gold Coast Seaway; 9/10/2012; 14:01 hrs; Austraeolis ornata; size 30mm; depth 2 metres; 20 degrees water temperature; 2 metres visibility; this was the first branch species for the day. Lots of Hypselodoris obscura, beautiful Dendrodoris denisoni, including a juvenile, a few Mexichromis mariei, Ceratosoma tenue, various Goniobranchus and bubble shells, Siraius nucleola, Hypselodoris jacksoni (exciting), and a tiny Goniodoridella savignyi (new record for me and possibly the dive site).

Patrik Good Eat or to be eaten? Siraius nucleola, Gold Coast Seaway; 9/10/2012; 14:22 hrs; size 18mm; depth 4 metres; 20 degrees water temperature; 2 metres visibility; Siraius nucleola has become a regular find at our dive site. It crawled away from an orange sponge. It seemed puzzled and tried to escape when all of a sudden a hydroid or a similar critter would get more and more agitated while trying to catch or scare away S. nucleola with its fangs. Does anybody have behavioral information relating to this observation?

Patrik Good This is hopefully an easy one because I see it floating in the water all the time. But I could never find an ID. Also photographed 22/5/2013 before dawn. Size about 3 to 4 cm (1 to 1.5 inches). Thanks for an id(ea).

Blogie Robillo Krill?

Arne Kuilman It's a common barnacle, Semibalanus balanoides. I've seen this behavior quite often. They can release themselves from the sediment to search for a new (less competition?) place to anchor themselves on the substrate.

Patrik Good Thank you both for solving this one with a surprise. It makes sense now actually. Who would have thought that the foe of one of my dive suits could ever show in such an innocent fairy-like form. Will have to read up on barnacles now. I have an unconfirmed theory based on an observation where a branch (Siraius nucleola) attacked the sedimentary form of this guy and was actually deterred by the wild flapping of the filter arms.

Animalia (Kingdom)
  Mollusca (Phylum)
    Gastropoda (Class)
      Heterobranchia (Subclass)
        Opisthobranchia (Infraclass)
          Nudibranchia (Order)
            Euctenidiacea (Suborder)
              Doridacea (Infraorder)
                Doridoidea (Superfamily)
                  Dorididae (Family)
                    Siraius (Genus)
                      Siraius nucleola (Species)
Associated Species