This solitary ascidian
is translucent and attaches via a wide base to the substrate.
siphons are on a flattened disk made up of several plates (see photo
There is a raised rim around the disk (photo).
The disk plates do not have concentric growth lines. The
connecting the two central disk plates (and those connecting other
as well) are visible through the tunic (photo).
Disk diameter up to 1.5 cm.
Chelysoma columbianum Huntsman, 1912
|Chelyosoma columbianum collected at
120 m depth west of Yellow
Island, San Juan Channel, WA. The scale below is millimeters
|(Photo by: Dave Cowles
How to Distinguish from
Similar Species: Chelyosoma
productum looks very similar but its disk plates
growth lines and the muscle strands connecting the two central plates
not visible (at least when preserved). It also can grow to
than 1.5 cm disk diameter and can occasionally be found intertidally.
General Notes and
abundances, unusual behaviors:
This closeup of the disk shows both the oral and the atrial apertures
and a few of the outlines of the plates the disk is made of.
white muscle fibers which bind the plates together are visible in the
behind the disk.
The two white, calcified-appearing lumps at the left end of the disk
appear to be part of the animal but I don't know what they are.
This side view of one of the siphons shows the raised rim of the plate
and the fact that the aperture is ringed with small
These are probably used to close the aperture.
Authors and Editors of Page:
Dave Cowles (2007): Created original page
CSS coding for page developed by Jonathan Cowles (2007)