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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.
Starfish are deuterostomes, closely related, together with all other echinoderms, to chordates, and are used in reproductive and developmental studies. Female starfish produce large numbers of oocytes that are easily isolated; these can be stored in a pre-meiosis phase and stimulated to complete division by the use of 1-methyladenine . [ 125 ]
Sea urchin tube feet extended past the spines.. 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.
The revelations, made possible by new methods of genetic sequencing, could help answer some of the biggest remaining questions about echinoderms, including their shared ancestry with humans and ...
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This is not, however, the case with echinoderms like starfish, sea urchins, and sea cucumbers. Instead, these creatures are driven by an unusual five-fold symmetry , also called radial symmetry.
Brittle stars, serpent stars, or ophiuroids (from Latin ophiurus 'brittle star'; from Ancient Greek ὄφις (óphis) 'serpent' and οὐρά (ourá) 'tail'; referring to the serpent-like arms of the brittle star) are echinoderms in the class Ophiuroidea, closely related to starfish. They crawl across the sea floor using their flexible arms ...
This echinoderm belongs to the family Echinometridae and it can reach a maximum diameter of 16–17 cm. [1] Kina populations throughout New Zealand have dramatically grown due to the effects of overfishing and climate change, resulting in over-grazing that significantly damages kelp forest ecosystems. Kina are now being actively removed from ...