Brittle stars in a tidal pool with marine plants. Brittle stars are marine invertebrates that are related to starfish. They have five flexible arms radiating from a central disc-shaped body, which means that unlike starfish they can use their arms to walk on the sea floor. The mouth is underneath their body. Some brittle stars scavenge on debris on the sea floor, while others filter food from the water. Photographed in Jambiani, Zanzibar, Tanzania.