Ascidia callosa

The Callused Tunicate

Phylum Chordata
Subphylum Urochordata
Class Ascidiacea
Order Phlebobranchia
Family Ascidiidae
Genus Ascidia
Species callosa

Description: Up to 5 cm across; translucent while young, brownish, growing opaque with age; usually coated with diatoms, algae and other small organisms; shape is generally hemispherical and flattened where attached to substratum; two small volcano shaped siphons located near the top.

Habitat: Found on floating docks and pilings, especially in protected areas.

Natural History: These solitary ascidians can often be found growing near one another. Found in a tire hanging off the dock at the Boston Harbor Marina.