Different Species of a Starfish

According to "National Geographic," although they have been called starfish for years, these animals aren't actually fish. More closely related to sea urchins and sand dollars, they have been renamed "sea stars" to more accurately reflect their place in the animal kingdom. With more than 2,000 species living in varying habitats all over the world, the sea star is one of the most diverse animals. Most varieties of sea star have five arms, but other species can have up to 40.

  1. Sunflower Sea Star (Pycnopodia Helianthoides)

    • As reported by Evergreen State College, the Sunflower Sea Star, which can be found from Alaska all the way down to California, can grow to 1 meter in diameter and have up to 24 arms. They can be yellow, brown, orange or purple, and they move using the extensions on their "feet," called podia. The Sunflower Sea Star is carnivorous and prefers to eat mollusks but will also eat mussels, oysters, sea cucumbers and dead fish. They capture their prey by smothering it with their stomach and secreting an enzyme that turns the animal into a liquid form that the sea star can absorb.

    Shallow-Water Sea Star (Oreaster Reticulatus)

    • As reported by Smithsonian Marine Station, the Shallow-Water Sea Star, which resides in the shallow waters of the Caribbean, was once the most common type of starfish. It is identifiable by its large, central disc, five short arms and red, orange, brown or yellow coloring. This species has a hard outer shell covered with knobby spines, protecting it from potential predators. They are known to grow up to 50 cm -- almost 20 inches -- in diameter, but their growth potential is affected by the amount of food available. In periods of starvation this species is able to reabsorb its own body tissue to sustain itself.

    Cushion Sea Star (Pteraster Tesselatus)

    • According to the University of Michigan, the Cushion Sea Star resides on the coast of North America in the Bering Sea, as well as around Alaska. This species can be cream, yellow, grayish purple or orange with a high disk -- up to 35mm (almost 1 1/2 inches) in height -- and five short, thick arms, giving it a cushion appearance. Their diet consists of sea sponges, scallops and the bacteria that live on the outside of mussels, and they digest their food by inverting their stomachs.

    Blue Linckia Sea Star (Linckia Laevigata)

    • Hobart and William Smith Colleges reports that the Blue Lincki, found from Africa to Hawaii and off the coasts of Thailand, Japan and Australia, is arguably one of the most beautiful species of starfish. Bright blue in color, at maturity they reach up to 25 cm (almost 10 inches) with five thin arms, each containing the same set of organs. Their diet includes the organic material on the sea floor, as well as sponges, mollusks, ascidians and bryozoans.