Starfish (also known as sea stars) are star-shaped echinoderms that belong to the class Asteroidea.

Despite having "fish" in their name, they are not related to fish at all, sea stars live underwater, and that's where the only resemblance to fish ends. Sea stars live only in salt water.

Sea water (instead of blood) is used to pump nutrients through their bodies with the use of the 'water vascular system' used by other echinoderms, such as sea urchins.

Starfish move (or attach tightly to objects, such as rocks) by using tube feet, each tube foot swings like a leg, lifting up and swinging forward.

Starfish are very fragile, and your own hands can be quite dangerous for all types of sea creatures (including starfish) due to the amount of bacteria that can be found on your hands alone, which can lead to a possible slow death for them.

Starfish do not attack humans, but some contain venom which is poisonous to human beings, they can inflict painful stings which will release the venom if they are stepped on or handled.

Touching a starfish or picking them up above the waves does not hurt them, however they should be placed back where they were found as soon as possible, however it's best to not handle one at all.

If a starfish's severed limb is not eaten by a predator, the severed limb can grow into an entirely new starfish.