Project Description

This Pacific white crust (Didemnum carnulentum) was a great find for me.  I thought it was a type of sponge, but Neil McDaniel clarified that it was actually a type of colonial tunicate.   The Pacific white crust is a fairly common species in kelp forest habitats.  Many small star shaped openings cover the surface of this colonial tunicate, as well as a few larger holes.  A colonial tunicate is made up of many small individuals called zooids.  These individuals each take water in and then as a group have common areas for expelling the filtered water.  This close-up image shows the individual zooid openings.  The filtering system of this colony is different from a solitary tunicate which has both an inhalant and exhalent siphon.  Pacific white crust colonies can reach five inches (12.5 cm) across, with a range from central British Columbia to Panama.


Click on the image below to see the entire Pacific white crust colonial tunicate.

Pacific White Crust colonial tunicate