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Mollusks and Segmented Worms

Mollusks and Segmented Worms. What you’ll learn: Identify characteristics of mollusks Describe the characteristics of segmented worms Explain the digestive process of an Earthworm. Mollusks- Not just a seashell!. Mollusks are any soft bodied animal that usually (not always) have a shell.

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Mollusks and Segmented Worms

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  1. Mollusks and Segmented Worms What you’ll learn: Identify characteristics of mollusks Describe the characteristics of segmented worms Explain the digestive process of an Earthworm

  2. Mollusks- Not just a seashell! • Mollusks are any soft bodied animal that usually (not always) have a shell. • The major parts of a mollusk are the mantle, a muscular foot and shell • A mantle is a thin layer of tissue that covers the soft body of a mollusk. The foot is used for moving or keeping the animal in one place. • A closed circulatory system allows blood to be carried in veins from the heart.

  3. Mollusks that live in water have gills and mollusks that live on land have lungs. • Most mollusks have a radula, a scratchy tongue made up of tiny teeth like points that help them scrape up food.

  4. NOTE CHECK! • 1. What are the 3 major parts of a mollusk? • 2. What is a radula? • 3. Do all mollusks have a shell?

  5. Types of Mollusks • Gastropods Often have one shell. Live in water or on land. Examples include a snail, slug and conch. • Bivalves Often have two shells. Connected by a hinge. Powerful muscles open and close the two shell halves. Examples include mussels, clams, oysters and scallops. • Cephalopods Most complex type of mollusk. Instead of a shell many have an internal plate and a hard beak (mouth). Their foot is divided into many tentacles with strong suckers on them. Their siphon helps to push water through their body to allow for fast motion. Examples include squid, octopus, chambered nautiluses and cuttlefish.

  6. Note Check! • 1. Which form of mollusk is the most complex? • 2. Give an example of a gastropod. • 3. An animal that makes pearls (an oyster) would fall into what category of mollusk?

  7. Gastropods

  8. Bivalves

  9. Cephalopods

  10. Segmented Worms • Consist of Earthworms (annelids), Leeches and Marine Worms (polychaetes) • Their bodies are made up of repeated segments or rings that make these worms flexible. Earth worms have over 100 body segments!

  11. Earth Worms • Earthworms get the energy they need to survive from nutrients in soil. • Earthworms have no gills OR lungs! They allow gas to pas through their slimy skin • Each part of the worm contains blood cells, nerve cells and part of the digestive system

  12. NOTE CHECK! • 1. How many segments can an Earthworm have? • 2. What is inside the segments of these worms?

  13. Marine Worms • Many marine worms are covered in bristles or Setae. • The bristles are used for walking, swimming or digging. • These are often filter feeders but they can also be predators or parasites. • Marine worms are the most diverse group of segmented worms

  14. Leeches • These are flat bodied worms often found in water. • These animals are parasites meaning they drink the blood of other animals. They have suckers on both ends to attach onto their host. • Some leeches can store over 10 times their own body weight in blood.

  15. Note Check • How does a leech get its food? • What are marine worms covered in?

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