1. Worms, Cnidarians, and Sponges
Review Sheet Answers

2. Sponges #1 What is an invertebrate?
Invertebrates are animals that do not have backbones.

3. Sponges #2
What does asymmetrical mean?
It has no symmetry.

4. Sponges #3 Define sessile.
An organism spends its life attached to one spot and does not move from place to place.

5. Sponges #4 What are pores? How do they help sponges?
Small openings that surround the entire body of a sponge. They allow water and oxygen to enter the sponge’s body.

6. Sponges #5 How do sponges obtain food and oxygen?
Water travels through the pores and it carries food and contains oxygen molecules. The specialized cells filter them out.

7. Sponges #6
Do sponges have tissues, cells, or organs?
CELLS!!

8. Sponges #7 What are spikes? How do they help sponges?
They form a rigid frame that helps support the sponge’s body. They also are a defense mechanism.

9. Sponges #8 Describe the two types of reproduction.
Asexually: Budding. Buds form on the parent sponge and eventually break off and float away.
Sexually: Fertilization. Sperm are released by a male sponge and then fertilize a female’s eggs.

10. Sponges #9 What is a larva?
A fertilized egg becomes a larva. It is the immature form of the adult and looks very different.

11. Cnidarians #10 What is radial symmetry?
Many lines of symmetry, all through a center point.

12. Cnidarians #11 How are cnidarians’ tentacles unique?
They have stinging cells.

13. Cnidarians #12 What is a nematocyst?
A capsule in the stinging cell that holds a barbed filament.

14. Cnidarians #13
Cnidarians are more advanced than sponges because they have….
TISSUES!

15. Cnidarians # 14 Describe the two types of reproduction of cnidarians.
Asexual – Budding (buds form on the adult, break off, float away, and then attach to the ocean floor).
Sexual – Sperm are carried to the egg where fertilization occurs.

16. Cnidarians # 15 What is a polyp? What is a medusa? Vase-like shape.
Mouth is on the top.
Sessile
What is a medusa?
Free swimming animal.
Mouth is on the bottom.
Looks like an upside down bowl.

17. Worms #1 What are the 3 types of worms? Flatworms: they are FLAT
Roundworms: they are ROUND
Segmented worms: they have SEGMENTS

18. Worms #2 What is bilateral symmetry?
Only one line of symmetry in the animal.

19. Worms #3
What is regeneration?
The ability to regrow body parts.

20. Worms #4 What is a parasite?
Organism that lives on or in another organism.

21. Worms #5 What is an eyespot?
Allow the organism to see light versus dark.
Planaria have them.

22. Worms #6 What are odor cells? Allows the organism to smell food.
Planaria have them.

23. Worms #7 How do planaria eat? They insert feeding tubes into the food.
Next, digestive juices start to digest the food outside the worm.
Finally, the feeding tubes bring the prey into the worm.

24. Worms #8
Where do most roundworms live?
Moist environments

25. Worms #9 What type of digestive tract do roundworms have?
Open at both ends or one way.

26. Worms #10 What are segments?
Tiny linked sections that cover the worm’s body.

27. Worms #11 Describe the digestive tract of segmented worms.
both ends – One Way.

28. Worms #12
Describe a closed circulatory system. What is it and why do some animals have it?
Blood moves through a connected network of blood vessels.
It is important because it allows animals to grow larger.

29. Worms #13 What does it mean that earthworms are scavengers?
They eat decayed plant and animal remains in soil.

30. Worms #14 Why do earthworms need moisture?
They get oxygen from the water that’s on their skin.
No moisture = no oxygen.

31. Worms #15 How do earthworms help gardeners and farmers?
Tunnels loosen soil and provide room for air, water, and roots, which promote plant growth.