Phylum Echinodermata and their Classes - QS Study
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Phylum Echinodermata are marine organisms. While the adults are radially symmetrical the larvae remain bilaterally symmetrical. The mouth is on the lower surface. The Echinodermata is a phylum containing some 13,000 extinct and 7,000 extant species. They have a water vascular system with tube feet. eg. star fishes, brittle stars, sea urchins and sea-cucumbers.

Living representatives are only found in marine environment, making the phylum the largest lacking terrestrial and fresh water forms.

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Phylum Chordata are phylum derives its name from one of the common characteristics of this group namely the notochord (Gr. noton, back + L. chorda, cord). The animals belonging to all other phyla of the Animal Kingdom are often termed ‘the non -chordates’ or ‘the invertebrates’ since they have neither notochord nor backbone in their body. The backboned animals (vertebrates), together with a few closely re-lated animals which do not possess a backbone, are included in this phylum. Most of the living chordates are familiar vertebrate animals. The chordates are of primary interest because human beings are members of this group.