Botrylloides violaceus.  Zooids are arranged in long rows with the common atrial openings periodically placed on one side of the rows and numerous ampullae on the other side.  Photocredit:  Doug Mason's Photostream on Flickr
Botrylloides violaceus orange color variant.  Branchial siphons are clearly visible.  Orange pigment cells localize along the endostyle and in the ampullae.   Left, 1X;  Middle, 3X;  Right, 4X Zoom.
StereoZoom Color Variant  Portraits
Light-orange color variant.  Branchial tentacles can be seem.  Endostyle is clearly shown.  4X zoom. 

Red-orange color variants of two different colonies. Zooids have more pigmented cells in deep-colored colories.  Left 4X zoom.  Branchial tentacles can be seen in image on right.  3X zoom.

Orange color variant showing pigmented ampullae between rows of zooids.  3X zoom.

Botrylloides violaceus.Right, numerous color variants including beige, pink, different shades of organge, brick red-orange, raspberry, maroon, and burgundy.  Left, Berrill (1947) illustrates arrangement of zooids, adaptation of zooid  atrial structure to curving rows, and placement of endostyle .
Botrylloides violaceus.  Common color variants in Provincetown, MA.  Orange, light-orange, and brick red-orange. 
Light-orange color variant growing on Codium.  0.7X zoom. 

Light-orange colony showing partial side-view of endotyle and branchial siphons .  4X zoom. 

Light-orange colony showing atial siphon (center).  .5X zoom. 

Orange colony showing zooids with a common atrial siphon. 4X zoom.