Clavelina coerulea or Rhopalaea fusca - very confusing online!

Cabilao, Oct 7, 2012
Elegant solitary ascidian, cylindrical, small (3-5 cm). Colour can change, but it is usually a blue tone: from transparent sky to an opaque darker blue. When disturbed, tunicates draw up the incurrent and excurrent apertures, much like a drawstring around the rim of a bag. Tunicates, or "sea squirts" are common in all marine habitats, attaching themselves to virtually any fixed object on a coral reef. To feed, they constantly filter out bacteria and phytoplankton by passing a continuous stream of water through their body. The larger of the two openings is the mouth, or incurrent aperture, and the smaller is the excurrent aperture. The water stream is kept moving by the action of tiny cilia (hairs) that line the inside of the tunicate body. Waste products are also expelled through the excurrent aperture.
Habitat:
Rhopalaea spp. are common on back reef, reef front but mainly along the external reef. Indo-Pacific