Botryllus spp.

The Pacific Star Tunicate

Phylum Chordata
Subphylum Urochordata
Class Ascidiacea
Order Stolidobranchia
Family Styelidae
Genus Botryllus

Description: Forms colonies 3 to 5 mm high, 5 to 10 cm wide; rubbery gelatinous matrix with orange, yellow, purple or green individuals arranged in circular or oval patterns which resemble stars; zooids share a common excurrent opening.

Habitat: Found growing on rocks, floats, pilings and docks near and just below the low-tide line.

Natural History: This tunicate can sometimes be seen hanging from docks in long wide ribbons in the water. Individual zooids live for one to two weeks, and colonies can exist for more than a year. Before a zooid dies it produces buds which not only replaces it, but also adds to the colony. These sedentary animals fall prey to many species of gastropods, flatworms, nudibranchs and other invertebrates. Classification of species is extremely difficult and experts are reluctant in attempting it.