Pacific Transparent Sea Squirt

Ciona savignyi

Ciona savignyi is a solitary, bottle or vase-shaped tunicate that can reach lengths of about 15 cm. It is characterized by its soft, gelatinous, translucent tunic, which is typically whitish or cream-colored and often reveals muscle bands and internal organs. The buccal siphon, located at the narrower end, is surrounded by eight yellow-edged lobes with orange-red spots, while the atrial siphon features six similar lobes. This species can be distinguished from the similar Ciona intestinalis by the presence of white flecks in its tunic wall and the reddish color associated with its buccal siphon. Native to Japan, Ciona savignyi has expanded its range to the west coast of North America, where it is considered an invasive species. It prefers shallow waters, often found in environments like docks, marinas, and aquaculture structures, typically at depths shallower than 40 meters. This species feeds by filtering planktonic particles from the water, drawing it in through the buccal siphon and expelling it through the atrial siphon. As a hermaphrodite, Ciona savignyi has the ability to reproduce both cross-fertilizing and self-fertilizing, although self-fertilization is not the norm due to the timing of gonad maturation. After fertilization, the eggs hatch into larvae that attach to a surface and undergo metamorphosis into juvenile tunicates. Encounters with this species during dives can reveal its distinctive shape and coloration, often found in dense patches that may compete with native species for resources.