[8] Their color ranges from bright orange, yellow-red to brown, and sometimes purple, with soft, velvet-textured bodies and 5–24 arms with powerful suckers.

[10] Between 2013 and 2015, the population declined rapidly due to sea star wasting disease[11] and warmer water temperatures[12] caused by global climate change.

[6] Ecologists using shallow-water observations and deep offshore trawl surveys found that, in their study period (2004–2017), mean biomass of sunflower sea stars declined 80–100%.

[8] There are suggestions that sea star wasting disease was caused by bacterial pathogens or parasites and was contagious, due to its tendency to spread to multiple locations.

[15] Sunflower sea stars generally inhabit low subtidal and intertidal areas up to 435m deep[16] that are rich in seaweed,[17] kelp,[18] sand, mud, shells, gravel, or rocky bottoms.

[21] Sea star appetites and food can depend on environmental factors in their habitats, such as climate, amount of prey in the area, and latitude.

[22] Easily stressed by predators such as large fish and other sea stars, they can shed arms to escape, which regrow within a few weeks.

In preparing to spawn, they arch up using about a dozen arms to hoist their fleshy central mass above the seafloor and release gametes into the water for external fertilization.

[28] On August 18, 2021, the Center for Biological Diversity created a petition asking that the sunflower sea star be protected under the Endangered Species Act.

[29] In March 2023, the National Marine Fisheries Service proposed listing the sunflower sea star as threatened under the act.