Most starfish have five feet, but some have four or six. The so-called foot is actually the wrist of starfish. Although it feels similar to the foot, it is actually different. The activities of starfish mainly depend on the dense tubular feet on its wrist, and the larger the starfish, the more tubular feet, even reaching thousands. With them, starfish can move on the seabed.

1. Banding: Banding is characterized by obvious edge plates, suction cups on the tube feet, and no skin gills. It generally lives on the soft seabed, can cave in sediment, and can crawl at the same time. Many deep sea starfish are for this purpose, such as albatross starfish, mud starfish and maple starfish.

2. Spinous order: The marginal plate of spinous order starfish is relatively small, the fork spine is relatively simple, and there are suction cups on the tube foot. Common species are camel petrels, round starfish and sun starfish, etc. These starfish have many short wrists and wide body disks.

3. Forceps: The characteristics of Forceps are different from other starfish. It has long-handled double-valved forked spines, which can play a protective feeding function. It is widely distributed, such as the Red Sea coaster living in Northern Europe, the spiny sea coaster in Bering Sea, and the short thorn bean starfish in North America. These starfish have many wrists, up to 50.