Read the Passage Below, Which Covers Topics from Your Textbook. Answer the Questions That

SPONGES

Phylum Porifera

Read the passage below, which covers topics from your textbook. Answer the questions that follow.

The basic body plan of a sponge consists of two layers of cells separated by a jellylike substance called mesohyl. In the simplest sponges, the body wall forms a hollow cylinder that is closed at the bottom and open at the top. The interior of the cylinder is lined with flagellated cells called choanocytes. By beating their flagella, choanocytes draw water into the sponge through numerous pores, called ostia, that penetrate the body wall. The water that is pumped into the interior of the sponge leaves through the osculum, the opening at the top of the sponge.

A sponge would collapse without some type of supporting structure. In some sponges, support is provided by a simple skeleton made of a network of protein fibers called spongin. Other sponges have skeletons consisting of spicules, tiny, hard particles of calcium carbonate or silicon dioxide. Still other sponges have a combination of spongin and spicules.

Read each question and write your answer in the space provided.

SKILL:Identifying Main Ideas

1.What is the main idea of the passage?

______

2.What is the basic body plan of a sponge?

______

3.How does water move into and out of a sponge?

______

4.The figure below shows the body plan of a sponge. Complete the figure by inserting the following labels: “Flagellum,” “Choanocyte,” “Spicules,” “Osculum,” “Interior of sponge,” and “Ostium.”

Circle the letter of the phrase that best completes the analogy.

5.Spicules are to sponge as

a.sidewalk is to concrete.

b.engine is to automobile.

c.frame is to house.

d.baseball is to bat.

PORIFERA

VOCABULARY REVIEW – Write the definitions of the following terms.

1. choanocyte______

______

2. osculum ______

______

3. spicule______

______

4. amoebocyte______

______

MULTIPLE CHOICEWrite the correct letter in the blank.

____1.Invertebrates are animals that lack

a.true tissues.b. true organs.c. a skeleton.d. a backbone.

____2.Adult sponges are sessile, which means that they

a.have no gastrula stage.c.use a jellylike substance for

body support.

b.attach to a surface andd.produce both eggs and sperm

do not move.

____3.Choanocytes perform all of the following functions except

a.pumping water into the interior of the sponge.

b.engulfing and digesting food that is filtered from the water.

c.passing nutrients to amebocytes.

d.distributing nutrients throughout the rest of the body.

____4.Sponges eliminate carbon dioxide and cellular wastes by

a.allowing them to diffuse into the water that passes through the sponge.

b.excreting them into the surrounding water through pores in the body wall.

c.transporting them to an excretory organ that empties into the osculum.

d.converting them into usable carbohydrates.

____5.After a sponge egg is fertilized, it develops into a(n)

a.external bud.b.gemmule.c.larva.d.gastrula.

SHORT ANSWERAnswer the questions in the space provided.

1. On what basis are animals placed into the invertebrate category? ______

______

2.______What are the two substances that a sponge’s skeleton may be made of? ______

How do these substances differ? ______

3. How do choanocytes participate in the sexual reproduction of sponges?

______

4. Why is hermaphroditism beneficial in sponges even though they rarely self-fertilize?

______

5. Critical ThinkingWouldgemmules or larvae be better at distributing a population of sponges through an area? Explain your reasoning.

______

STRUCTURES AND FUNCTIONSIdentify the structures labeled a–e in the diagram of a sponge shown below.

Modern BiologyPorifera