An array of 24 arms distinguishes this magnificent sunflower star from other sea stars. Soft skin in colors ranging from purple to brown, orange or yellow adds to its beauty. For a sea star, this animal is a voracious predator. When on the prowl for food, the sunflower star swings along on its 15,000 tube feet—moving at the remarkable speed of over 40 inches (1 m) per minute.
The sunstar's prey use a variety of escape tactics to avoid being trapped by the Pycnopodia's tube feet. Snails and abalones violently twist their shells to loosen the star's powerful grip; cockles lower their strong foot and pole-vault away; California sea cucumbers, usually sedentary, slither out of the way; and sea urchins flee. Both red and purple sea urchins deploy their pedicellariae (pinchers) to nibble on the star's tube feet. The purple urchin seldom escapes, however the red sea urchin has another defense—long spines, which usually ensure its escape.
Urban runoff and sewage spills harm sea stars and all creatures that live off our coasts. When you visit the shore, it's best just to look, not touch or disturb the animals and plants that live there. Persistent ill-treatment of a sunstar can leave it in poor condition.
Juvenile sunflower stars start life with five arms—by maturity they have up to 24 arms.
Most sea stars have a one-piece, semirigid skeleton. However, the sunflower star's skeleton has a few disconnected pieces. They allow the sunstar's mouth to open wide and its body to enlarge and take in big prey.
A sunflower star can swallow an entire sea urchin, digest it internally and then expel the urchin's test—its external shell.