1. For each pair of terms, explain how the meanings of the terms differ.

a. spongin and spicule b. medusa and polyp c. epidermis and gastrodermis d. cnidocyte and nematocyst e. gemmule and planula

2. Explain the relationship between choanocytes and filter feeding.

3. Use each of the following terms in a separate sentence: colloblast, apical organ, and bioluminescence.

4. Word Roots and Origins The name Porifera is derived from the Latin porus, meaning "channel," and ferre, meaning "to bear." Explain why Porifera is a good name for the sponge phylum.

Understanding Key Concepts

5. Identify three ways that sponges represent the transition from unicellular to multicellular life.

6. Describe why sponges are classified as animals.

7. Outline the path of water through a sponge, and explain what causes water to flow through a sponge.

8. Explain how a sponge's usual method of feeding is suited to its sessile lifestyle.

9. State the role of gemmules in the life cycles of sponges.

10. Summarize the process of sexual reproduction in sponges.

11. Compare the two types of body structures that cnidarians have.

12. Describe how a cnidarian captures and ingests its prey.

13. Identify the specialization that is found among the individuals that make up a Portuguese man-of-war.

14. Name the benefits a sea anemone obtains from its symbiotic relationship with a clownfish. What benefit does the clownfish obtain from this relationship?

15. Explain why coral reefs are limited to warm, shallow environments.

16. Compare ctenophores and cnidarians. Include at least two differences.


CONCEPT MAPPING Use the following terms to create a concept map that sequences sexual reproduction in a typical scyphozoan: adult male, medusa, blastula, adult female, sperm, polyp, planula, and egg.

Critical Thinking

18. Applying Information A single species of sponges may assume various appearances, depending on substrate, availability of space, and the velocity and temperature of water currents. How might these factors make the classification of sponges confusing? What features besides outward appearance can biologists use to classify sponges and eliminate some of this confusion?

19. Analyzing Information Sponge larvae have flagella on the outside of their bodies, while adult sponges have flagella lining their internal cavity. How is this structural difference related to functional differences between the larval and adult stages of sponges?

20. Analyzing Patterns Hydras generally reproduce asexually during warm weather and sexually in cooler weather. Based on what you have learned about the hydra embryo, what is the advantage of reproducing sexually when the weather turns cool?

21. Predicting Results What would happen to a coral reef if pollution or sediment caused the water around the reef to become less clear? Explain your answer.

22. Interpreting Graphics The pie chart below shows the relative numbers of hydrozoans, scypho-zoans, and anthozoans. Which segment of the chart represents scyphozoans? How do you know?

w Standardized Test Preparation

DIRECTIONS: Choose the letter of the answer choice that best answers the question.

1. Why are spongin and spicules important to a sponge?

A. They digest food.

B. They remove wastes.

C. They provide support.

D. They produce offspring.

2. Which of the following structures are involved in both feeding and sexual reproduction in sponges?

F. spicules and gemmules

G. amoebocytes and spongin

H. gemmules and choanocytes

J. choanocytes and amoebocytes

3. Which of the following is not a characteristic of cnidarians?

A. tentacles

B. choanocytes

C. nematocysts

D. gastrovascular cavity

4. What do colloblasts do?

F. They produce light.

G. They secrete a sticky substance.

H. They draw water through sponges.

J. They form medusae that live in colonies.

INTERPRETING GRAPHICS: The diagram below illustrates a hydra. Study the diagram to answer the questions that follow.

5. Identify the substance found at point 3.

A. osculum

B. mesoglea

C. gastrodermis

D. gastrovascular cavity

6. Which structure is involved in defense?

DIRECTIONS: Complete the following analogy.

A. mouth

B. tentacle

C. nerve net

D. nematocyst

INTERPRETING GRAPHICS: The diagram below illustrates a medusa. Study the diagram to answer the question that follows.

8. In which class is this body form dominant?

F. Cnidaria

G. Hydrozoa

H. Anthozoa J. Scyphozoa

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