Phoronids for the Fourth

Eric and his summer students spotted these wonderful phoronids, Phoronis vancouverensis, at the Spud Point Marina docks yesterday (3 July 2017):

 

Remember that phoronids are known for their beautiful lophophores, the U-shaped crown of tentacles shown below:

 

 

While looking at these phoronids, we noticed some of the lophophores looked a little different — some had paired white spots in the center of the lophophore:

 

Here's a closer look (below).  Note that each of the white spots looks like a little bunch of grapes (clusters of smaller rounded blobs).  Do you have a guess about what they are?

 

The next image is the closest I could get with my camera at the time:

 

Each of the white clusters is a group of small developing embryos. Phoronis vancouverensis is a brooder!  The embryos will develop within the lophophore for about 2 weeks.  Then the tiny larvae will swim away, spending time in the plankton before returning to the benthos and undergoing metamorphosis into tiny juvenile phoronids.

I felt fortunate to be photographing phoronids on the Fourth of July!  :)

P.S.  For more information about phoronids, review the post from 27 June 2013.