Meet the 24-armed sea star, a kelp forest's bodyguard

Meet the 24-armed sea star, a kelp forest's bodyguard

While they have no backbone, sunflower sea stars (Pycnopodia helianthoides) mean business–especailly when faced with spiny sea urchins. These 24-armed, roughly 3-feet-wide sea stars can move 40 inches per minute when on the prowl for crabs, snails, sea urchins, and other ocean creatures to eat.  Sea urchins appear to sense the sea star’s presence–desipte not having a brain–and avoid these predators, according to a study recently published in the…