How many arms do most starfish have?

Starfish or sea stars are star-shaped echinoderms belonging to the class "Asteroidea".

All starfish resemble stars and usually have only five arms, though there are some exceptions with up to 40 arms. Many species are brightly colored in various shades of red or orange, while others are blue, grey or brown. Starfish have tube feet operated by a hydraulic system and a mouth at the center of the oral or lower surface. Most can regenerate damaged parts or lost arms and they can shed arms as a means of defense. Sea stars have an eye spot at the end of each arm. This means that a five-armed sea star has five eyes.

Instead of blood, sea stars have a circulatory system made up primarily of sea water.

There are about 2,000 species of sea stars. Some live in the intertidal zone and others live in the deep water of the ocean. While many species live in tropical areas, sea stars can also be found in cold areas - even the polar regions.