<i>Baseodiscus</i> the Eldest: First Report of a Decades‐Long Lifespan in a Nemertean Species

Nemertea is a speciose phylum of marine invertebrate predators ubiquitous in the world's oceans, which includes Lineus longissimus (Gunnerus, 1770)-the world's longest documented extant animal, yet much about the life histories of these remarkable animals remains poorly understood. For example, it is not known how long nemerteans live. We report a maximum known age of a nemertean individual, identified by morphology and DNA-barcoding as belonging to Baseodiscus punnetti (Coe, 1904), which has been kept in aquaria for at least 26 years. This finding confirms previous speculations that at least some species of nemerteans may live for many years and highlights a dearth of knowledge of the longevity of nemerteans and of marine invertebrates more broadly.