What is the difference between saving an Excel file in .xlsx and in .csv? Would it be better to import into R using .xlsx or .csv?
The phylum Echinodermata, which contains about 6000 species, gets its name from the Greek, literally meaning âspiny skin.â This phylum exists exclusively in the sea and includes sea stars, urchins, brittle stars, and sea cucumbers. They are simple animals, lacking a brain and complex sensing organs.
An echinoderm is a sea animal that has a hard spiny shell, or exoskeleton. Echinoderms display radial symmetry, having 5 similar body extensions from a central point.  The se â¦ ven classes of echinoderms are brittle stars, basket stars, sea urchins, sand dollars, sea lilies, feather stars, and sea cucumbers.chinoderms have swimming larvae that are bilaterally symmetrical, with left and right sides, but they do not 'develop into' bottom-living adult echinoderms, which are radiall â¦ y symmetrical, often star-shaped. The juvenile (young adult), radial from the start, grows from a group of stem cells within the larva.