3. Indicate if they are domestic or wild animals:

      4. Types of invertebrate animals

      Invertebrates are the simplest and smallest animals, but their diversity is greater than the vertebrates. They can be grouped into three classes:

   - Unicellular Animals or protozoa: They live in both freshwater and saltwater and can be observed through the microscope. For example: amoebae (without membranes and it can deform) radiolaria (with skeleton and bones)

   - Animals with radial symmetry, they have the body parts as a wheel, such as sponges, coelenterate (jellyfish) and echinoderms (starfish).

   - Animals with long body, which usually have the head at one end, such as mollusks (snail), worms and arthropods (crab).

   5. Indicate the correct answer: protozoa, animals with radial symmetry or animals with long body

6. Sponges    The sponges are invertebrates that live in water. Their bodies are perforated by numerous pores which communicate with a central cavity. They live in colonies attached to the seabed. For example: common sponge and bath sponge.

7. Coelenterates    Coelenterates often live at the bottom of waters forming colonies. they have radial tentacles and that is the reason why they looks like a flower. Colonies look like shrubs and flowering plants. The fixed coelenterates are called polyps and the swimmer coelenterates are called jellyfish .

     8. Select if they are sponges or coelenterates:

9. Echinoderms    The body of echinoderms has radial form. As we see in the left picture, the starfish has five points. The arms are easily broken and the body reproduces. The sea urchin has hemispherical shape and its skeleton is composed of plates that form a rigid shell. Another echinoderm is the sea cucumber with elongated and cylindrical shape.

10. Mollusks    The mollusks have soft body, head, visceral mass and locomotor organs with shape of tentacles like octopus or with muscular foot like snail. Others are protected by a shell as the mussel.

     11. Indicate if these animals are echinoderms or mollusks:

The sea Urchin
The mussels
The sea Cucumber
The snail
The octopus

---

12. Worms    Worms have a cylindrical body, divided into numerous segments and legless. The taenia is the parasite of the pig and man, absorbing much food that they eat. The leech sucks the blood of other animals and man. The earthworm lives in the soil, feeds of organic rest and is beneficial to man and earth. The Ascaris lives in the small intestine mainly in children and it can cause injuries.

---

    13. Choose the correct answer: sponge, coelenterate, echinoderm, mollusk or worm

®Arturo Ramo García.-Record of intellectual property of Teruel (Spain) No 141, of 29-IX-1999
Plaza Playa de Aro, 3, 1º DO 44002-TERUEL