Starfish to starfish by the French zoologist de Blainville in 1830. It is derived from the Greek "aster", ἀστήρ (a star) and the Greek "eidos", εἶδος (form, likeness, appearance). The class Asteroidea belongs to the phylum Echinodermata. As well as the starfish, the echinoderms include sea urchins, sand dollars, brittle and basket stars, sea cucumbers and crinoids. The larvae of echinoderms have bilateral symmetry, but during metamorphosis this is replaced with radial symmetry, typically pentameric. Adult echinoderms are characterized by having a water vascular system with external tube feet and a calcareous endoskeleton consisting of ossicles connected by a mesh of
Pacific spiny dogfish half of the shark has a gray color with scattered white spots while the bottom half has a white/light gray color. The scales of the dogfish is composed of the same material of shark teeth called dermal denticles, making the skin very hard and durable. The skin of the sharks used to be used as sandpaper once dried to do woodwork or even be used as leather, once the denticles are removed. Lastly, the Pacific spiny dogfish has a set of teeth specialized for grinding instead of tearing by the teeth being flat with sharp edges. If any of the