Students should learn that starfish (properly names "sea stars") are not fish, but invertebrates (animals without a backbone) that live in saltwater. Focus on their star-like shape with a central disc and arms, how they move with tube feet, their ability to regrow arms, and their unique ability to digest food by extending their stomachs outside their bodies. They have spiny skin, no brain, and can sense light and dark, all while emphasizing that they are animals. Teach students about Jellyfish by including information like the fact that they are made up of 95% water. They have no brain, heart, bones, blood or eyes. Because jellyfish don't have gills, they absorb oxygen through their skin. Some jellyfish have light sensors called eye spots that can sense sunlight so they know which way is up.