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Video showing the tube feet movement of a starfish Close up starfish at Wakatobi National Park, 2018. The scientific name Asteroidea was given to starfish by the French zoologist de Blainville in 1830. [93] It is derived from the Greek aster, ἀστήρ (a star) and the Greek eidos, εἶδος (form, likeness, appearance). [94]
Tube feet (technically podia) are small active tubular projections on the oral face of an echinoderm, such as the arms of a starfish, or the undersides of sea urchins, sand dollars and sea cucumbers; they are more discreet though present on brittle stars, and have only a feeding function in feather stars. They are part of the water vascular system.
When alert to movement in the water nearby, the rings of pedicellariae are extended, ready for action. If anything touches its aboral (upper) surface, the starfish reacts by snapping shut the pedicellariae in the vicinity of the stimulus. By this means it can catch prey items such as small fish. [3]
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 ...
Starfish that brood their young generally lack a bipinnaria stage, with the eggs developing directly into miniature adults. The bipinnaria is free-living, swimming as part of the zooplankton . When it initially forms, the entire body is covered by cilia, but as it grows, these become confined to a narrow band forming a number of loops over the ...
An echinoderm (/ ɪ ˈ k aɪ n ə ˌ d ɜːr m, ˈ ɛ k ə-/) [2] is any animal of the phylum Echinodermata (/ ɪ ˌ k aɪ n oʊ ˈ d ɜːr m ə t ə /), which includes starfish, brittle stars, sea urchins, sand dollars and sea cucumbers, as well as the sessile sea lilies or "stone lilies". [3]
Madreporite of Asterias. In sea stars, water enters the system through a sieve-like structure on the upper surface of the animal, called the madreporite.This overlies a small sac, or ampulla, connected to a duct termed the stone canal, which is, as its name implies, commonly lined with calcareous material.
The long, pointed tube feet are specially adapted for movement over soft sediments, but lose traction if the sand star tries to scale steeply sloping rocks. It is a fast traveller, and can move across the seabed at the rate of 280 centimetres (110 in) per minute, [ 4 ] many times faster than slow species such as the leather star ( Dermasterias ...