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A bipinnaria is the first stage in the larval development of most starfish, and is usually followed by a brachiolaria stage. Movement and feeding is accomplished by the bands of cilia. Starfish that brood their young generally lack a bipinnaria stage, with the eggs developing directly into miniature adults.
Smaller starfish feed on isopods, pelecypods and chitons. Larger starfish also feed on amphipods , polychaete worms and the limpet Nacella delesserti , which makes up 90% of its diet by mass. The feeding method depends on the relative size of starfish and victim.
Starfish or sea stars are star-shaped echinoderms belonging to the class Asteroidea (/ ˌ æ s t ə ˈ r ɔɪ d i ə /). Common usage frequently finds these names being also applied to ophiuroids, which are correctly referred to as brittle stars or basket stars. Starfish are also known as asteroids due to being in the class
To feed on one of these, the starfish moves over it, attaches its tube feet and exerts pressure on the valves by arching its back. When a small gap between the valves is formed, the starfish inserts part of its stomach into the prey, excretes digestive enzymes and slowly liquefies the soft body parts.
The common starfish, common sea star or sugar starfish (Asterias rubens) is the most common and familiar starfish in the north-east Atlantic. Belonging to the family Asteriidae , it has five arms and usually grows to between 10–30 cm across, although larger specimens (up to 52 cm across) are known.
The starfish must broaden their diet from their preferred species, colony size, and shape. The starfish often aggregate during feeding, even at low densities, but during high densities, the cleared coral patches become almost or completely continuous. Second-order effects exist for these large areas of preyed coral:
A starfish has five identical arms with a layer of “tube feet” beneath them that can help the marine creature move along the seafloor, causing naturalists to puzzle over whether sea stars have ...
The species is also considered in reef aquariums. It feeds on the surface of the stones in thin layers of algae, so it can live only in an old well-ripened aquarium. If the algae are not growing fast enough, supplemental feeding is usually unsuccessful, and this starfish dies of starvation.