New Zealand Common Cushion Star

Patiriella regularis

Patiriella regularis is a pentagonal sea star commonly found along the rocky shores of New Zealand. It typically has five short arms, although some individuals may have four, six, seven, or eight arms. The coloration of this species varies widely, with blues, greens, and browns being the most prevalent, alongside occasional oranges and reds. This starfish thrives in shallow waters, inhabiting rocky reefs, sandy areas, and intertidal zones, often at depths of less than 12 meters. It is particularly abundant in harbors such as Otago and Whangateau, as well as in Fiordland's Doubtful and Milford Sounds. Additionally, it has been recorded in the Kermadec Islands and has spread to parts of Southern Australia and Tasmania, where it may impact native species. Feeding primarily on crustose coralline algae and microorganisms, Patiriella regularis is an omnivore that also consumes carrion and small invertebrates. Its reproductive cycle includes both asexual reproduction by fission and sexual reproduction, with external fertilization occurring in favorable environmental conditions. The species has a complex life cycle, with larvae developing through bipinnaria and brachiolaria stages before metamorphosing into juvenile sea stars. Encounters with this species during dives can be common, as they dominate many suitable habitats. However, they are susceptible to diseases such as sea star wasting disease, which can lead to mass mortality events. Patiriella regularis is classified as Not Evaluated by the IUCN, reflecting the need for further research on its population status and ecological impact.