Chapter 15
Animals
Have you ever seen a living sea star (shown right)? Sea stars
(group name Stelleroidea) are sometimes called starfish,
though they are not real fish. But like fish, sea stars are
animals. So is a tree frog, a dog, a luna moth, and a great blue
heron (all shown right). You can probably name many other
types of animals. What characteristics do all animals share?
What characteristics do scientists use to place animals into
different categories? Read this chapter to learn more about
different groups of animals.
- What do you have in common with a worm, sea
star, frog, fish, and a bird? - Why is a sponge an animal?
- Why is the sea squirt one of your distant
cousins?