Quick answer
Starfish, also called sea stars, are marine invertebrates in the class Asteroidea, named for their typically five-armed, star-shaped bodies. They have no brain or blood and move using hundreds of tiny tube feet powered by seawater. Many can regrow lost arms, and some can regenerate an entire body from a single limb. Most live around 5 to 35 years depending on the species.
Key takeaway
Starfish, also called sea stars, are marine invertebrates in the class Asteroidea, named for their typically five-armed, star-shaped bodies. They have no brain or blood and move using hundreds of tiny tube feet powered by seawater. Many can regrow lost arms, and some can regenerate an entire body from a single limb. Most live around 5 to 35 years depending on the species.
Overview
Starfish, also called sea stars, are marine invertebrates in the class Asteroidea, named for their typically five-armed, star-shaped bodies. They have no brain or blood and move using hundreds of tiny tube feet powered by seawater. Many can regrow lost arms, and some can regenerate an entire body from a single limb. Most live around 5 to 35 years depending on the species.
Biology
Starfish (Asteroidea) is classified as Invertebrate with conservation status Least Concern. Typical weight about 0.5 kg; lifespan around 5–35 years depending on species.
Ecology
Diet: Carnivore (mollusks, clams, mussels). Habitat: Ocean floors, from tide pools to the deep sea. Movement and social systems reflect those pressures.
People and this species
Learn before you travel or keep related pets. Wild individuals are not toys; captive care needs species-specific husbandry.
Further reading
See the full Starfish profile for FAQs, taxonomy, and related guides on this site.
Body without a brain
A starfish has no brain and no blood. Instead of blood it pumps filtered seawater through a water vascular system that powers movement and circulation. A simple nerve ring and nerves running down each arm let it sense light, touch, and chemicals, and a tiny eyespot at the tip of each arm detects light and dark.
Tube feet and movement
The underside of each arm is lined with hundreds of small tube feet that extend and grip using water pressure and suction. These let a starfish creep slowly across the seabed and pry open the shells of clams and mussels. Movement is gradual, measured in centimeters per minute rather than any quick dash.
Regeneration
Starfish are famous for regrowing arms lost to predators or injury, a process that can take months to over a year. In some species a severed arm that keeps part of the central disc can grow into a whole new animal. This regenerative ability is one of the most remarkable in the animal kingdom.
Feeding and habitat
Many starfish feed by pushing their stomach out through their mouth to digest prey such as mussels and clams outside the body, then drawing the liquefied meal back in. They live on ocean floors worldwide, from shallow tide pools and reefs to the cold deep sea. A few species, such as the crown-of-thorns starfish, can damage coral reefs during population outbreaks.
Research notes
Figures for starfishs (Asteroidea) come from field studies, museum records, and conservation assessments that do not always agree on exact averages. Prefer ranges over single-point claims, and check whether a source describes wild, captive, or mixed populations.
Practical takeaways
If you encounter starfishs in the wild, prioritise distance and local guidance. If you care for related domestic or captive animals, match diet and housing to species needs rather than generic pet advice. Share accurate status information (Least Concern) when discussing conservation.
Sources
FAQs
Starfish: Key Facts & Natural History?
Starfish, also called sea stars, are marine invertebrates in the class Asteroidea, named for their typically five-armed, star-shaped bodies. They have no brain or blood and move using hundreds of tiny tube feet powered by seawater. Many can regrow lost arms, and some can regenerate an entire body from a single limb. Most live around 5 to 35 years depending on the species.
What is the scientific name of the starfish?
Asteroidea
What do starfishs eat?
Carnivore (mollusks, clams, mussels)
Where do starfishs live?
Ocean floors, from tide pools to the deep sea
Are starfishs endangered?
Listed here as Least Concern. Check IUCN and national lists for the latest assessment.