Starfish

Starfish are fascinating creatures that live in the sea and typically have five arms. They have a round central body from which their arms extend. Although they appear soft, their bodies are actually somewhat rigid.

Starfish are not fish, but they live in the sea. They belong to a group of animals called echinoderms. Approximately 1500 different species of starfish live in many parts of the world, from warm tropical seas to cold polar waters.

Illustration of a starfish. (Generated by artificial intelligence.)

What Do Starfish Eat ?

Starfish particularly enjoy eating shelled marine animals such as mussels, oysters, and snails. They can also consume small fish, worms, and sometimes even decaying animal matter.

Illustration showing the feeding behavior of starfish. (Generated by artificial intelligence.)

Where Do Starfish Live ?

Starfish live in oceans and seas. They cannot survive in freshwater environments such as lakes or rivers.

You can find them:

• Near shorelines,
• Between rocks,
• In coral reefs,
• In deep seas, and even sometimes in extremely cold polar waters.

They can live in seas all over the world, regardless of whether the water is warm or cold. They require only clean, salty water.

Illustration of a starfish floating in the sea. (Generated by artificial intelligence.)

Ecological Roles of Starfish

Some starfish species are keystone species in their ecosystems, meaning their numbers and behavior directly affect the survival of many other organisms. For example, the species Acanthaster planci, which feeds on coral polyps, is an important predator of coral reefs.

Illustration showing the feeding behavior of the Acanthaster planci starfish on coral polyps and its role as a keystone species in the ecosystem. (Generated by artificial intelligence.)

Feeding in Starfish

• Most starfish are carnivorous and feed on mussels, oysters, snails, small fish, and other invertebrates.
• Some species feed on algae (herbivorous), while others consume decaying organic matter (detritivorous).
• Their feeding method is remarkable: they use their suction-cupped tube feet to pry open the shells of their prey, then extend their stomachs outside their bodies to digest the soft tissues.

Illustration depicting the feeding mechanism of starfish. (Generated by artificial intelligence.)

References

Ault, Larissa, Juliet McCardle, and Caitlin Sussman. 2011. "Acanthaster planci." Animal Diversity Web. Accessed March 20, 2025. https://animaldiversity.org/accounts/Acanthaster_planci/.

"Sea Stars." Science Learning Hub. The University of Waikato. Accessed March 20, 2025. https://www.sciencelearn.org.nz/resources/149-sea-stars.