On Online Market Rather than on Science, a Comprehensive Study on the Global and Bathymetric Distribution of the Deep Ocean Sea Urchin Coelopleurus Maillardi (Arbaciidae)

Despite today’s technologies, some species (especially deep-water ones) are still almost unknown to science and their distribution along the globe is still debated. Nonetheless, some of these species can be found online, targeted by collectors and jewel making. One of such species is the deep-water sea urchin Coelopleurus maillardi. This species has very few documented sightings, most of which date back to the early 1900s; however, it is currently being sold online due to its brightly colored test. In this study, a comprehensive review of all the literature and documented sight occurrences available on this species was performed and the results were compared with those from e-commerce listings. This allowed for nearly doubling the reported sight cases of this species, while updating a dataset that has remained mostly unchanged for almost 100 years. The results suggest some shifts in the global and bathymetric distribution of this species over the past century, and mostly reconfirmed and expanded previous knowledge. Among these identified changes, there appears to be a shift towards deeper water, a concentration of this species on the Philippines and the China coast, and its disappearance from Indonesia. These trends suggest potential changes in the ecosystems where this species lived over the past 100 years.