1. Write down whether the following statements are true or false. Give extensive answers.

1. The sponges arose from a protozoan group.

2. Sponges are found in salt water.

3. Wandering amoeboid cells are found between the two layers of the body of a simple sponge.

4. Most sponges are supported by nothing.

5. The skeletons of the dead sponges are added to the remains of coral animals.

2. Complete the sentences using the text and translate them into Russian.

1. … gives definite indication …

2. The majority of sponges …

3. … by numerous pores … the central cavity.

4. The sponge skeletons, … , play an important role in the formation of flint.

3. Answer the following questions on the text in written form.

1. Why were adult sponges thought to be plants at one time?

2. Are individual sponges simple or complex in structure?

3. What does a simple sponge consist of?

4. How does water, carrying food and oxygen, enter the central cavity of a sponge?

5. How does a sponge get rid of waste products?

6. What may the skeleton of a sponge be made up of?

7. What assists in the building of coral reefs and islands?

8. What is the common “bath sponge”?

4. Translate a passage into Russian in written form. Text 7 coelenterata

Animals Included in Phylum Coelenterata

The word "coelenterate" means "hollow inside". This refers to fact that (1) the members of this phylum have a pouch-like digestive cavity, with a single opening to the outside that connects with this cavity.

The coelenterates are considered to be more highly developed than the sponges because they show greater specialization and division of labour. Although the body consists of only two layers of cells, we find that there are special cells for digestion and protection, special nerve cells and muscle cells, and general surface cells. Practically all coelenterates have stinging cells which are used both for food-getting and for defense.

This phylum includes over 4000 species. They are widely distributed, but are for the most part marine. Some occur singly, while others are found in colonies showing various degrees of complexity. Coral, coral reefs and coral islands are the accumulated skeletons of coelenterates.

The coelenterates exhibit radial symmetry. This means that the planes of symmetry radiate from a central point like the spokes of the wheel and any plane passing through it from top bottom will divide it into two equal parts, This type of symmetry is in contrast to bilateral symmetry, there is only one possible plane that will divide the animal into two parts, each of which is mirror image of the other.

The coelenterates show two types of body organizations. The polyp type is cylindrical or elongated in shape and is usually sedentary. The medusa type (jelly fish) is shaped like an umbrella and is free-swimming. All coelenterates, whether of the polyp or medusa-type are built on the same general plan.

Tasks

1. Write down whether the following statements are true or false. Give extensive answers.

1. The members of Phylum Coelenterata have a digestive cavity without an opening to the outside.

2. This phylum doesn’t include many species.

3. Coral reefs are the accumulated skeletons of coelenterates.