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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 .
Echinoderms possess a simple digestive system which varies according to the animal's diet. Starfish are mostly carnivorous and have a mouth, oesophagus, two-part stomach, intestine and rectum, with the anus located in the centre of the aboral body surface. With a few exceptions, the members of the order Paxillosida do not possess an anus.
The oral or lower surface of the disc has a central mouth surrounded by further scales. The ambulacral grooves are wide and run down the centre of the oral side of each ray. There are widely separated narrow scales on either side of the grooves with two spines on each, one overlapping the groove and the other projecting from the side of the ray.
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.
The body outline is similar to that of starfish, in that ophiuroids have five arms joined to a central body disk. However, in ophiuroids, the central body disk is sharply marked off from the arms. [5] The disk contains all of the viscera. That is, the internal organs of digestion and reproduction never enter the arms, as they do in the Asteroidea.
For decades, scientists theorized a starfish didn’t have heads. A new study finds that they might, in fact, only have heads. A Study Says Starfish Are Basically Walking Heads, and Literally ...
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 ...
Here’s what to do if you find a jellyfish, starfish or octopus on a SC beach, DNR expert says. Eleanor Nash. November 7, 2023 at 6:00 AM. 1 / 3.