Starfish are not actually fish. They have no brains, scales, gills, or fins. Sea stars, like their sand dollar and sea urchin cousins, have no backbone. This means they are part of a group called invertebrates. Fish have backbones, which makes them vertebrates.
Sea stars can regrow an arm if one becomes broken. It takes around a year to grow a new one! The most common types of starfish have 5 arms, but they can have more. The Sunflower Sea Star can have up to 40 arms!
Starfish have hundred of small tube feet on each arm. These feet have strong suction cups, which help them not get swept away by strong currents. They use these tube feet to move, but they move very slowly. On each arm, they have an "eye spot", which helps tell them whether it is light or dark.
Sea stars are carnivores, which means they are meat-eaters. Their favorites include mollusks like clams, oysters, and sea snails. They eat their prey by pushing their stomachs out of their mouth and into their prey's shell to eat it.