Although widespread, ranging throughout the Atlantic and Pacific Oceans, you'll rarely encounter this oceanic dwelling salp on either coast.  It's a close relative of the various species of Salpa and is difficult to distinguish from them.  For single individuals (as in the photo) the best characteristics are the cylindrical body, thin soft test, 9 muscle bands, and terminal oral and atrial (posterior) openings.  The small spherical compact gut is located at the posterior end.  Zooids are aligned in the same direction as the chain axis for aggregates.   Individuals within the aggregate each have 5 body muscles, with oral and atrial openings pointed dorsally.   

All photographs © David Wrobel and may not be used or copied without permission!