The Northern Pacific seastar primarily feeds on bivalves, such as clams and mussels, as well as other marine organisms like coral and sponges. Its main predators include larger fish, sea otters, and some species of birds.
This seastar is harmful to native species because it aggressively competes for food and habitat, outcompeting native predators and prey, which can lead to declines in native marine populations and disrupt the ecosystem balance in the Great Barrier Reef.