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sea star
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Introduction References & Edit History Quick Facts & Related Topics
Images & Videos
sunflower starfish high Arctic sea star
Study how sieve plates and suction-cupped tube feet enable sea stars to catch prey and move through water
watch a starfish's tube feet pry open a mussel's shell and extrude its stomach onto the mussel
Observe sea star reproduction, from egg and sperm release and fertilization to development of zooplankton embryos and larvae
Crown of thorns starfish (Acanthaster planci). firebrick starfish Red starfish.
examine a variety of echinoderm species such as starfish, basket star, sand dollar, and sea cucumber
Principal features of a starfish. Water for the water vascular system enters through the madreporite and passes into a ring canal and on to radial and lateral canals, from which it enters the tube feet, which are connected to saclike ampullae on top. Contraction of the tube feet forces water into the ampullae, creating suction that allows suckers at the ends of the feet to hold to a surface. When the ampullae contract, water is forced into the feet, extending them and releasing the suction. These coordinated actions permit movement, attachment, and capture of prey. In many starfish, the cardiac stomach is everted through the mouth on the body's undersurface to envelop prey, and digestion may begin outside the body before the stomach is drawn back in.
For Students
starfish summary
Quizzes
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sea star: Media

echinoderm

Videos

Study how sieve plates and suction-cupped tube feet enable sea stars to catch prey and move through water
Anatomy and physiology of starfish tube feet.
Video: Encyclopædia Britannica, Inc.
watch a starfish's tube feet pry open a mussel's shell and extrude its stomach onto the mussel
Starfish preying upon a mussel.
Video: Encyclopædia Britannica, Inc.
Observe sea star reproduction, from egg and sperm release and fertilization to development of zooplankton embryos and larvae
Learn about sea star reproduction by observing the release of eggs and sperm, egg...
Video: Encyclopædia Britannica, Inc.
examine a variety of echinoderm species such as starfish, basket star, sand dollar, and sea cucumber
Echinoderms exhibit a variety of body plans. The starfishes are also called sea stars....
Video: Encyclopædia Britannica, Inc.

Images

sunflower starfish
Sunflower starfish (Pycnopodia helianthoides).
Casey Debenham/Census of Marine Life
high Arctic sea star
High Arctic sea star found in the Canadian Basin of the Arctic Ocean.
Bodil Bluhm and Katrin Iken—NOAA/Census of Marine Life
Crown of thorns starfish (Acanthaster planci).
K. Gillett/World Life Research Institute
firebrick starfish
Firebrick starfish.
© diverstef/Fotolia
Red starfish.
© Fallsview/Dreamstime.com
Principal features of a starfish. Water for the water vascular system enters through...
© Merriam-Webster Inc.
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