Other Colonial Ascidians

There are hundreds of other species of colonial ascidians that live on the docks of Sausalito. Here are a few.

Botryllus schlosseri (puple morph)

Some varients of an animal are so similar that they are grouped together as "morphs" of the same species. The colony to the left is a purple morph of the familiar B. schlosseri. The tissue is very dark, which makes it difficult to photograph. This image is not very good, but it's the best of several dozen I took.

There are six zooids in this small colony, and each zooid has two white bars which bracket their intake siphon. The common exit siphon is in the middle of the six zooids, but in this image, where we are looking from the right side of the colony, the exit is displaced to the left.

Ghost tunicate

These tunicates have a shape like a potato, are very translucent, and often grow around and engulf other objects, the bryzoan in this image.

The intake siphons can been seen only as "holes" in the pattern of small white pigments spots on the surface of the tunicate. The stomach of each zooid was visible by eye, but this feature doesn't show well in this image. The common exit siphon is on the upper, right side of the animal.

This tunicate may be a "Pale Mushroom Tunicate" or Polyclinum pannosum [see CH28, pg 353, Lamb & Hanby]. I quote from this excellent reference "For the amateur naturalist who uses external anatomy to identify species, it is very difficult to distinguish many of the compound tunicates." They are preaching to the choir.

The exit siphon is very clear in the image on the left; it's at the upper edge of the animal.

An important diagnostic for a tunicate is that it retracts when probed. The Ghost tunicate passes this test, but I can't prove this to you with this still image.

In the middle of the frame on the right is another, almost translucent, colonial tunicate. I have used back illumination to reveal the dozens of small zooids that make up the colony.

The common exit siphon is to the extreme left (ringed by dark debris).