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 phylum Echinodermata includes about 7,000 living species. Members of Echinodermata are often called echinoderms. They are invertebrate animals that have radial symmetry, which means they have similar structures in several directions around a central point. In most starfish, this radial symmetry is consistent in five directions.