Different Kinds of Starfish

Starfish are part of the family known as echinoderms, which also includes sea urchins and sea cucumbers. Like all echinoderms, starfish have a basic structure of arms or spines radiating with radial symmetry from a central body. Starfish can be found throughout the world's oceans in a variety of habitats including coastal waters, coral reefs and deep sea trenches.

  1. Sea Stars

    • Probably the most recognizable as a starfish are the star-shaped sea stars, or Asteroidea. They can have between five and 11 arms, depending on the species. They are all carnivorous, with mouths located on the underside of their bodies. They feed by extruding their stomachs out through their mouths. The stomach covers the prey, which is then digested outside of the body. Sea stars can be found around coral reefs as well as on rocky or sandy sea floors.

    Feather Stars

    • Feather stars, or Crinoidea, are a delicate, often attractive variety of starfish. They share the same symmetrical body shapes as sea stars, but the limbs are more feather-like and fragile looking. Depending on species, feather stars can have anywhere from five to 200 arms. They can be one of many striking colors, such as deep red, blue and bright yellow. They spend much of their time clinging to rocks or coral trying to trap plankton. Some species are capable of swimming by contracting their arms.

    Brittle Stars

    • Brittle Stars, or Ophiuroidea, look similar to sea stars but have thinner, more ungainly looking arms. They have a smaller central body than sea stars. They tend to be nocturnal, hiding amid coral and rocks during the day and coming out after dark to feed on plankton or small mollusks. As the name would suggest, these types of stars are fragile. They can easily lose limbs, but they quickly grow back. They are the fastest moving of all the echinoderm species.

    Basket Stars

    • Basket Stars, or Astroboa nuda, are a type of brittle star but are distinctly different in several ways. Basket stars are a mixture between a sea star and a feather star. Its arms are covered in feathery offshoots. It uses these feathery limbs to filter water for plankton. When threatened, the basket star will close its arms inward to its center, making it appear like a rounded wicker basket. Like brittle stars, the basket star can easily lose limbs but quickly regrow them.