Starfish –Phylum Echinodermata

Starfish Dissection shell Aboral surfaceOral surface Madreporite is opening of the water vascular system Mouth Tube feet are the terminal end of the water vascular system

Starfish Dissection shell Starfish can evert their stomach through their mouths and begin digestion of the prey outside the body Gonads may be big or small depending on season ampulla

Starfish Dissection Radial canals in each ambulacral ridge Ring canal Radial canals in each ambulacral ridge Water Vascular System Water comes in the madreporite, travels through the stone canal to the ring canal and then flows through the radial canals in each arm. The short transverse canal connects the radial canal with the ampulla. When the ampulla fill with water, they contract and move the tube feet. ampulla

Phylum Echinodermata (means spiny skin) Asteriodia – sea stars = starfish Crinoidia – sea lilies Echinoidea – sea urchins and sand dollars Holothuroidea – sea cucumbers Opiuroidea – brittle stars

Phylum Echinodermata Habitat: marine Symmetry: Bilateral larva, radial symmetry in adults Body Cavity: coelomate Development: Deuterostome Skeleton: spicules embedded in dermis or a calcareous endoskeleton composed of spines/ossicles