However, it seldom frequents the intertidal zone because its soft flabby body would quickly dry out in the sun. Even clams, which lie hidden in the bottom sediments, are not safe from the Sunflower Star. Once this efficient hunter detects the siphon hole of a clam, it excavates the clam, protrudes its stomach, envelops the entire clam and digests it. Most species of sea stars have a mesh-like skeleton that protects their internal organs, but restricts their mobility. Despite its formidable size, the Sunflower Star attains speeds of 1.6 metres per minute as it pursues its prey.
Some animals can detect the oncoming sea star and evade it.
The usually-sluggish Northern Abalone transforms into a speedster when attacked by the Sunflower Star. The abalone's large fleshy foot goes into strong undulations as it moves away from the sea star, and its shell twists violently in an attempt to dislodge the sea star's suckers. Sunflower Stars can breed from March to July, but the main peak is in May and June. They shed eggs and sperm into the water, where fertilization takes place by chance. After the larval period, the larva settles to the bottom and transforms into a miniature Sunflower Star.