1. Comparing Living Things
Science
Unit A – Chapter 1
Comparing Living Things

2. Lesson 3: How Are Animals Classified?

3. Animals Without Backbones
Animals that have no backbones are called invertebrates.
Invertebrates are many-celled organisms.
Sponges, jellyfish, worms, sea stars, mollusks, and arthropods are all examples of invertebrates.

4. Sponges Look more like plants than animals Live underwater
Do not move -- They attach themselves to rocks or other objects in the water.
Trap and eat tiny organisms that float in the water that flows in and out of their hollow bodies

5. Jellyfish Have hollow bodies that water flows in and out of
Have a mouth surrounded by tentacles
Tentacles are used to capture prey.

6. Mollusks Have soft bodies Bodies are protected by one or two shells.
We eat many of these.
Snails, oysters, and clams are examples of mollusks.

7. Sea Stars Live on the ocean floor
Use suction cups on their underside to stay in place and to pry open shells
Tough skin and spines protect them from enemies.

8. Arthropods This groups contains more than 80% of all animal species!
Lobsters, crabs, spiders, centipedes, millipedes, and insects (70%) are examples.
Have a stiff outer covering called an exoskeleton for protection.
The exoskeleton has joints that allow movement.

9. Worms Live mostly underground
Eat the remains of dead plants and animals
Have narrow, tubelike bodies
Flatworms have flat bodies.
Roundworms look like tiny snakes with no heads.
Earthworms are examples of segmented worms.

10. Animals With Backbones
Animals that have backbones are called vertebrates.
There are five groups of vertebrates.
Fish
Amphibians
Reptiles
Birds
Mammals

11. Fish Live their whole lives in the water Use tails and fins to move
Take in oxygen from the water through their gills
Lay eggs in water
Range in size from 1 inch to 50 feet long

12. Amphibians Lay eggs in water
Live part of their lives in water (with gills) and part on land (with lungs)
Usually stay near water
Frogs and salamanders are examples.

13. Reptiles Breathe with lungs their whole lives
Bodies are covered with tough, dry scales.
Most lay leathery-shelled eggs on land.
Lizards, snakes, turtles, alligators, and crocodiles are examples.

14. Birds Breathe air all their lives Lay hard-shelled eggs on land
Hollow bones make their bodies light.
Bodies are covered with feathers.
Not all birds fly!

15. Mammals Have hair or fur on their bodies
Breathe through lungs all their lives
Mammals are the only animals that feed their young with milk produced by the mother.
Mammals give birth to live young.
Live on land, in water, and in the air

16. Questions
What are invertebrates?
What are vertebrates?