Sunflower Sea Star (Pycnopodia helianthoides)
Sunflower stars are the fastest moving and largest of the sea stars in our area. They can move up to 4' a minute, which is far faster than any of the other sea stars we commonly see as divers. They stay well below the intertidal area because their fragile body requires the support of surrounding water to keep from collapsing. They range in depth as low as 1450 feet. Their fuzzy appearance is caused by their gill structures, which are numerous, small, and bag shaped.
The scientific name is Pycnopodia helianthoides. Pycnopodia, meaning dense feet, referring to the thousands of tube-like suckers on the underside of each arm. Helianthoides means resembling a sunflower. This sea star can grow to 39 inches in diameter; reaching its greatest size in the rich waters of Puget Sound, British Columbia and Alaska.
Sunflower stars are carnivorous and their diet includes numerous species such as sea urchins, clams, crabs, snails, sea cucumbers, sand dollars, chitons and dead fish. This varied diet enables the Sunflower Star to forage and feed in various habitats from mud to solid rock. Sunflower Stars are a favorite food of King Crabs.
A sunflower star starts it life with five or six arms, but these multiply as it grows to fifteen to twenty-four arms as an adult. Most species of sea stars have a mesh-like skeleton that protects their internal organs, but restricts their mobility. The skeleton of the Sunflower Star's upper surface is comprised of a few unconnected pieces; this design allows its mouth to stretch and its body to distend to accommodate and engulf large prey.
Sunflower Stars breed in May and June, arching up stiffly and releasing their eggs and sperm into the water column, where fertilization takes place by chance. The microscopic sea star larva floats and feeds near the surface for two to ten weeks. After the larval period, the larva settles to the bottom and transforms into a miniature Sunflower Star. The life span of most sea stars is 3 – 5 years.