1. Life Science
Classifying Animals

2. sponges, asymmetrical 1. The simplest animals are ________________.
They are without real tissue or organs and have
an _____________ body plan.

3. cnidarians, radial
2. Jellyfish, sea anemones, corals, and hydras are __________________ . They are soft-bodied, aquatic creatures with _______________ symmetry.

4. more than one
3. Organisms with radial symmetry have body parts arranged around a central point with ___________ line of symmetry that divides the organism into two mirror images.

5. bilateral
4. There are three main worm groups: flatworms, roundworms, and segmented worms. All worms have ________________ symmetry, or one line of symmetry.

6. mollusks, bilateral
5. Clams and squids are ________________. They have __________________ symmetry, a
muscular foot, a mantle, and several specialized
organs.

7. echinoderms 6. Sea stars and sea cucumbers are __________.
They have tubed feet and a water
pressure system that helps them feed, breathe,
and move.

8. arthropod, exoskeleton
7. Crabs and insects belong to the largest animal
group on Earth, the ____________ phylum.
They are small and light with a hard skeleton on
the outside of the body called an ___________.

9. jawless, cartilaginous, bony
8. There are three kinds of fish: ___________, such as lamprey and hagfish; _____________, such as sharks and skates; and ____________.

10. amphibians
9. Frog, toads, and salamanders are _________________. Amphibians spend part of their lives in water and part of their lives on land.

11. reptiles, cold-blooded
10. Lizards, snakes, turtles, and alligators are
_________________. They are _____________,
which means they must steady their body
temperature by sunning themselves during the day.

12. hollow 11. Birds are designed for flying: they are warm-
blooded and have _____________ bones, and feathers that are light and strong.

13. mammals
12. Animals that are warm-blooded,have hair, and produce milk for their young are _______________.

14. monotreme, marsupial, placental
13. Mammals are divided into three subclasses: _________, ___________, and ___________.

15. monotreme 14. A duck-billed platypus lays eggs. It is a
___________________.

16. marsupial 15. A kangaroo is a _______________. It gives
birth to partially developed offspring.

17. placental mammals
16. Lions, whales, and humans are _____________ mammals because their young develop within the mother.

18. Sort the organisms based on their body symmetry.
Critical Thinking
Sort the organisms based on their body symmetry.
Radial
A, E
Bilateral
B, D
Asymmetrical C