Icy Tunicate

Corella willmeriana

Corella willmeriana is a solitary tunicate found in the eastern Pacific Ocean, thriving on the seabed at depths reaching up to 75 meters. It is typically encountered between Alaska and California, often residing on firm substrates like rocks and fouling panels. The tunicate has a distinctive appearance, characterized by its transparent or translucent tunic, which can be smooth or irregularly wrinkled. Individuals are usually more than 1 cm in diameter and have both oral and atrial siphons of similar length, making them identifiable among solitary ascidians that do not reproduce by budding. The body is taller than wide, and the rectum is notably more than three-fourths the height of the body. As a hermaphroditic species, Corella willmeriana breeds year-round, with fertilization occurring in the atrial chamber. The larvae develop into free-swimming tadpoles before settling onto clean surfaces, where they undergo metamorphosis into benthic adults. While they play a role in fouling communities, they also face threats from predation by flatworms and polychaetes, as well as competition from colonial ascidians and potential smothering by diatom blooms during spring. Diving encounters with Icy Tunicates can be interesting, as they are often found in clusters on the seabed, providing a glimpse into the marine life of the Pacific. Observers may appreciate their unique morphology and the ecological roles they play in their habitats, although their conservation status remains unassessed by the IUCN.