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date: 22 October 2021

p. 708. Deuterostomes I: starfish, sea squirts, and amphioxuslocked

p. 708. Deuterostomes I: starfish, sea squirts, and amphioxuslocked

  • Peter Holland


‘Deuterostomes I: starfish, sea squirts, and amphioxus’ is concerned with some of the phyla of the Deuterostomia superphylum — the Echinodermata, Hemichordata, and the Chordata subphyla tunicates and amphioxus. The five classes of echinoderms — starfish, sea urchins, brittlestars, sea cucumbers, and sea lilies — have much in common with each other, but little with anything else. They display five-fold, or pentaradial, symmetry that has evolved from bilateral symmetry. Acorn worms and pterobranchs, part of the Hemichordata phylum, are described. The chordates can be split into three evolutionary groups, or subphyla — tunicates (such as sea squirts and larvaceans), vertebrates, and a group of marine chordates called cephalochordates, more usually referred to as amphioxus.

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