| Listen The "Clypeasteroida" (sand dollar) lives in the ocean. It has a rigid internal skeleton and spikes with very small hairs that help it move. These spikes are made up of cells that work together to perform a specific function. The sand dollar is multicellular. Each of its cells have a nucleus and other organelles. It has a "mouth-like" organ on its underside that allows it to eat. (You can use the chart below to help you.) Phylum a. Identify the domain of the organism. Give 1 justification for why you selected this domain. b. Identify the phylum of the organism. Give 2 justifications for why you selected this phylum. c. One of your students thinks this organism is in the Porifera phylum. Give 2 justifications for why this is not the appropriate classification. Example(s) Has a dorsal Type of Have Other notes symmetry tissues/organs nerve cord Porifera Glass Sponge No None No tissues Specialized cells to "Sponge" filter food Cnidaria Jellyfish No Radial Tissues Soft-bodied with (Cnidarians) stinging tentacles Mollusca Mussels, Snail, No Bilateral Organs Soft-bodies, some (Mollusks) Octopus have internal/external shell Annelida Earthworm No Bilateral Organs Segmented body, (Annelids) Leeches closed circulatory Arthropoda Swallowtail No Bilateral Organs (Arthropods) (butterfly), Crayfish, Ant system Exoskeleton, jointed appendages, segmented body (Annelids) Leeches Arthropoda Swallowtail No Bilateral Organs (Arthropods) (butterfly), closed circulatory system Exoskeleton, jointed appendages, segmented body Crayfish, Ant Echinodermata Sea Star No Radial Organs Internal skeleton (Echinoderms) Sea Urchins Chordata Sea Squirt, Yes Bilateral Organs Typically has an (Chordates) Dolphin, Sea internal skeleton Lamprey, See diagram of Alligator, classes Trout, Gull