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.
The adults are recognizable by their (usually five-point) radial symmetry, and include such well-known animals as starfish, sea urchins, sand dollars, and sea cucumbers, as well as the sea lilies or stone lilies. Echinoderms are found at every ocean depth, from the intertidal zone to the abyssal zone.he planktotrophic larva is considered to be the ancestral larval type for echinoderms but after 500 million years of larval evolution, about 68% of species whose development is known have a lecithotrophic larval type.