During Bilateria development, inner tube can open to outside anus first {deuterostome}, not head first as in protostomes.
Deuterostome worms {lampshell} (Brachiopoda) can live in ocean and have coelom. Lampshells have a top carbonate shell and a bottom carbonate shell. Lampshells are oldest genus with living members. Brachiopoda and Phoronida share common ancestor, from which Enchinodermata ancestors split.
Deuterostome worms {phoronid} (Phoronida) and Brachiopoda have a common ancestor, from which Enchinodermata ancestors split.
Starfish, sea star, sea urchin, sea cucumber, serpent star, and sea lily {starfish} {echinoderm} (Enchinodermata) are deuterostomes, live in ocean, have radial symmetry, have central disc, have five to twenty arms, and have mouth on underside. Starfish have no ganglia and no circulatory, respiratory, or excreting system. Brachiopoda and Phoronida share common ancestor, from which Enchinodermata ancestors split. Hemichordata ancestors and Echinodermata and Pterobranchia ancestors split.
Starfish can pump water {water vascular system}, to move and to open prey.
Enchinoderms {sand dollar} (Clypeasteroida) (superorder Gnathostomata) (class Echinoidea) can be flat and circular, have spines, and have five-star patterns. They relate to sea stars, sea urchins, and sea cucumbers.
Enchinoderms {sea cucumber} (Holothuroidea) can have cucumber shapes, flexible bodies, and tentacles.
Enchinoderms {sea urchin} (Echinus) (class Echinoidea) can have shells, long spines, tube feet, and five movable mouth parts.
Enchinoderms {sea star} can have star shape and five or more arms with tube feet.
Euryale, Astrophyton, and Gorgonocephalus {basket star} have slender branched crossed arms.
Worms {acorn worm}| (Enteropneusta) can live at ocean bottom, have proboscis attached to collar at cylindrical body top, and eat organic matter. Hemichordata ancestors and Echinodermata and Pterobranchia ancestors split. Chordata ancestors and Hemichordata ancestors split.
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Date Modified: 2022.0225