Compound sea squirt

<em>Diplosoma listerianum</em>, commonly known as the Compound sea squirt, is a colonial tunicate belonging to the class Ascidiacea within the phylum Chordata. This invertebrate typically forms thin, gelatinous sheets or encrusting colonies on hard substrates such as rocks, shells, pier pilings, and kelp holdfasts in marine and estuarine environments. Individual zooids are embedded within a shared transparent tunic, each drawing water through an oral siphon to filter microscopic phytoplankton, suspended organic particles, and bacteria—the primary dietary strategy for this sessile filter feeder. The species has a remarkably wide geographic range, occurring across temperate and subtropical coastal waters in South Africa, multiple European nations, Canada, the United States, Panama, New Zealand, Argentina, and Brazil, suggesting it may be partly spread through ballast water or hull fouling. It typically inhabits shallow subtidal and intertidal zones across multiple biome types, including temperate broadleaf forest-adjacent coasts and Neotropical shorelines. Currently classified as Data Deficient by the IUCN, population size and trend data remain insufficient to assess its conservation status accurately. Biological traits such as lifespan and individual dimensions remain poorly documented in the scientific literature for this colonial organism.