Stalked jellies

When I was an undergraduate student, I had considerable interest in marine invertebrates, particularly the simpler groups such as the jellies and comb jellies. While I soon turned my attention more to marine algae and later to higher plants, I still find that these simple groups of marine invertebrates are fascinating to behold. They are simple, elegant, and beautiful.

Tidepooling at Trinidad in Humboldt County in late June this summer I found interesting examples of a less common group of these soft bodied, simple invertebrates. I am pretty sure I have not seen these organisms in the field before, but have been aware of them for a while. Classified in the Phylum Cnidaria, this group is known as the Stauromedusae, Staurozoans, or stalked jellies. Cnidaria are comprised of many soft-bodied, often translucent invertebrates that many are familiar with including anemones, corals, and jellyfish. The stalked jellies are sometimes given their own taxonomic class, or order within the class that includes pelagic jellyfish.

The dozen or so animals I found at Trinidad were in shallow pools in the low intertidal zone, each animal only about 2-3 cm in size. They were attached to blades of red algae by an elongated stalk. The other end of the animal broadly flared out like a trumpet and included eight tentacles. Because these animals are very small, perhaps they have been at other sites up and down the Pacific coast I have explored and I have just overlooked them in the past.

I don’t know much about the biology of these organisms, but Dr. Claudia Mills at the University of Washington has a nice summary here. More images of Staurozoans can be seen here.