Starfish live in oceans and seas around the world; they thrive in salt water and live in tropical and temperate waters alike. These hardy creatures generally congregate far below the surface of the water and spend most of their time crawling along ocean floors.
Starfish, despite having tough outer shells, are classified as invertebrates, which means they lack backbones. They are relatively small compared to other organisms in ocean ecosystems, but that does not mean they are easy prey. These creatures have tough outer shells that are virtually impossible for would-be predators to fracture. Therefore, starfish need little assistance in the area of personal protection; while small fish and tiny shelled creatures hang out around rock crevices, hide in coral gardens and find shelter amongst tall seaweeds, starfish happily crawl across the sands of the ocean floor. Their shells act as shields, keeping starfish safe from harm as they feed on organic matter and debris. According to National Geographic, over 2,000 species of starfish live in oceans around the world. Of these organisms, most have five arms, but others generate 10, 20, and up to 40 limbs.