Invertebrates

1. Invertebrates 8. Snails and Clams

2. The largest group of invertebrate water animals is called mollusks Vocabulary: mollusk An invertebrate water animal with a soft body

3. Many mollusks have shells that protect their soft bodies There are six (6) main groups, or classes of mollusks

4. Some have one or two parts to their shells, while others have more Many mollusks have no shells at all

5. Snails are mollusks with one-part shells Snails are found in fresh water and in salt water

6. Snails are hermaphrodites which means they have both male and female parts

7. Most snails have two tentacles with eyes on them Vocabulary: tentacles Feelers that grow out of the head of some invertebrate water animals

8. Some freshwater snails have gills Vocabulary: gills Body parts that let fish and other water animals take in oxygen that is dissolved in water

9. Other freshwater snails have lungs Lungs These snails must come to the surface of the water often to get the oxygen they need

10. Some freshwater snails feed on algae which they eat by grinding it with their tongues There are thousands of tiny teeth on their tongues

11. Many saltwater snails have cone-shaped shells These ocean snails have a long tube

12. The tube takes in water which passes over the gills The gills take oxygen out of the water for the snails to breathe

13. Ocean snails also have two tentacles with eyes on the ends

14. Cone-shaped snails do not eat plants. Acorn Worm They eat water animals, such as worms, smaller mollusks, and tiny fish

15. They have a poison sac, or pouch, hooked to their teeth They can poison an animal so it cannot move, then they eat it

16. Clams are mollusks that have shells with two parts The two parts are held together by hard tissue called ligament

17. Vocabulary: ligament A hard tissue that acts like a hinge to open and close a clam shell

18. Clams live in saltwater and freshwater environments They dig into sandy ocean beaches.

19. They live on the muddy bottoms of oceans, ponds, and rivers in many parts of the world The giant clams that live near Australia have 4-foot-long shells that can weigh 500 pounds

20. A clam has a foot Vocabulary: foot A muscle under the body of a clam

21. The foot helps the clam to move It acts as an anchor to keep the clam in one place

22. If a clam is touched gently, it may use its food like a shovel It quickly digs itself under the sand

23. Hiding is one way a clam protects itself from animals that feed on clams

24. How else can a clam protect itself? Remember, a clam has a ligament that can close the two parts of its shell

25. Other water animals want to eat the soft body of the clam, not the hard shell If other animals are about to attack, a clam uses its ligament to snap its shell tightly shut

26. Two tubes stick out of the clam from the end that is opposite its foot Water is sucked into one tube

27. The water carries bits of plants and animals that the clam eats Microscopic Water Bear The water also carries oxygen

28. The clam has gills that help get the dissolved oxygen out of the water The other tube pushes out water that carries waste materials from the clam