starfish
Sign in to saveStarfish or sea stars are a class of marine invertebrates generally shaped like a star polygon. (In common usage, these names are also often applied to ophiuroids, which are correctly referred to as brittle stars or basket stars.) Starfish are also known as asteroids because they form the taxonomic class Asteroidea (). About 1,900 species of starfish live on the seabed, and are found in all the world's oceans, from warm, tropical zones to frigid, polar regions. They can occur from the intertidal zone down to abyssal depths, at below the surface.
AI overview
Starfish are star-shaped marine animals belonging to a class of invertebrates found in oceans worldwide, from shallow tropical waters to deep polar regions. With approximately 1,900 species living on the seabed, starfish are a diverse and widespread part of ocean ecosystems across all depths and climates.
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Article
34 sectionsContents
- Anatomy
- Body wall
- Water vascular system
- Digestive system and excretion
- Sensory and nervous systems
- Circulatory and gas exchange system
- Secondary metabolites
- Life cycle
- Sexual reproduction
- Larval development
- Asexual reproduction
- Regeneration
- Lifespan
- Ecology
- Distribution and habitat
- Diet
- Ecological impact
- Threats
- Evolution
- Fossil record
- Diversity
- Living groups
- Extinct groups
- Phylogeny
- External
- Internal
- Human relations
- In research
- In legend and culture
- As food
- As collectables
- References
- Bibliography
- External links
Starfish or sea stars are a class of marine invertebrates generally shaped like a star polygon. (In common usage, these names are also often applied to ophiuroids, which are correctly referred to as brittle stars or basket stars.) Starfish are also known as asteroids because they form the taxonomic class Asteroidea (). About 1,900 species of starfish live on the seabed, and are found in all the world's oceans, from warm, tropical zones to frigid, polar regions. They can occur from the intertidal zone down to abyssal depths, at below the surface.
Starfish are echinoderms and typically have a central disc and usually five arms, though some species have a larger number of arms. The aboral or upper surface may be smooth, granular or spiny, and is covered with overlapping plates. Many species are brightly coloured in various shades of red or orange, while others are blue, grey or brown. Starfish have tube feet operated by a hydraulic system and a mouth at the centre of the oral or lower surface. They are opportunistic feeders and are mostly predators on benthic invertebrates. Several species have specialized feeding behaviours including eversion of their stomachs and suspension feeding. They have complex life cycles and can reproduce both sexually and asexually. Most can regenerate damaged parts or lost arms and they can shed arms as a means of defense.