Phylum Echinodermata is the phylum most closely related to phylum chordata. The 6000 species that make up this phylum do not show body segmentation and redially grow fr the most part. Almost all the species r Marin. Few can live in blackish water. There r 5 major classes in phylum Echinodermata . 1.subphylum Blastozoa 2. Subphylum Crinozoa.3. Subphylum Echinozoa 4. Subphylum Esterozoa and 5. Subphylum Homalozoa.
These are spiny skinned animals like sea lily, sea star, sea urchin etc. That r exclusively marine, solitary sedentary or free living n benthoic. Radially symmetrical with pentameruous symmetry. They r spherical, elongated or star shaped. The body is without a will defined head.
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