Search carefully beneath rocks at low tide, and you may find the Long-armed Brittle Star, a sea star relative. With five arms and a central disk, brittle stars look a lot like sea stars but differ in many ways.

Brittle stars are called "brittle" because their arms readily break off when handled roughly or attacked. Like sea stars, these creatures re-grow lost limbs. They also have tiny tube feet lining the undersides of their arms, but brittle stars don't use these tube feed to move. Instead, they position some arms ahead, others behind or to the side, and push and pull themselves quickly along. The Long-armed Brittle Star also moves by wriggling its snake-like arms. Its central disk or body is only a half inch across, but each arm can be more than 7 inches long.

The Brittle Star's tube feet give traction, absorb oxygen, and both sense food and pass it to the creature's mouth beneath its disk. Unlike sea stars, brittle stars can't project their stomachs outside to envelop food. The Long-armed Brittle Star buries itself in sand, the tube feet moving grains from beneath to atop the arms and disk, slowly sinking the animal from sight. Once buried, the star extends its snaky arms above the sand and snares bits of dead animals and plants passing in the current. Brittle stars in shallow water come out after dark and scavenge for food on the seafloor.

If you lift rocks at the beach to see what's beneath, be sure to replace them exactly as they were. Fragile creatures like the brittle star depend on the care you take.