Elephant Ear Tunicate

Polyclinum planum

Polyclinum planum, commonly known as the elephant ear tunicate, is a compound ascidian found primarily along the Pacific coast of North America, from northern California to Baja California. These colonies exhibit a range of colors from olive green to brown and yellowish tan. They are typically attached to hard substrates in the intertidal zone and can also be found at depths of over 30 meters. The colonies can vary in size, with the zooid-bearing lobe becoming laterally compressed as the colony grows, sometimes reaching widths significantly greater than their thickness. This tunicate feeds by filter-feeding, utilizing rows of cilia-lined openings in its pharynx to pull water and capture small particles, including phytoplankton and detritus. The species is hermaphroditic, producing eggs year-round that develop into small, non-feeding larvae. These larvae swim briefly before settling on a hard substrate and metamorphosing into zooids, which are genetically identical due to the colony's cloning process. Encounters with Polyclinum planum during dives often reveal large colonies clinging to rocky surfaces, particularly in intertidal zones. However, they can be susceptible to dislodgment from heavy surf, making their presence in certain areas variable. The species has not been evaluated for conservation status, but its populations may be affected by climate change, leading to shifts in their geographic range.