The sunflower sea star occurs throughout intertidal and subtidal coastal waters of the Northeast Pacific Ocean from the Aleutian Islands, Alaska, to at least northern Baja California, Mexico. They are found to a depth of at least 435 meters on various substrate types, from rocky kelp forests to sand and mud flats.
Sunflower sea stars are broadcast spawners that require close proximity to mates for successful fertilization.
There is no single, systematically collected data set that provides population size or long-term trend data for sunflower sea stars throughout their range. However, from 2013-17, an outbreak of sea star wasting syndrome contributed to precipitous population declines in several areas, with impacts largely progressing sequentially from south to north. Disease, specifically sea star wasting syndrome, is the primary threat to the species. The influence of environmental stressors, including those associated with anthropogenic climate change, on disease risk are unresolved and are a major research focus.
