Inside a starfish
Most species of starfish have five arms but there are families that have 50 arms in multiples of five, and also a few with seven arms. They feed by turning their stomach inside out and squeezing it into the shells of molluscs. The tube feet that line each arm are controlled hydraulically to let the starfish glide slowly along the seabed and they are sticky to help pull apart mollusc shells.
To learn more about all the incredible animals on our planet, why not visit our AnimalAnswers website – from the makers of How It Works.