Chapter 6 Lesson 1 "How Animals Get and Digest Food" (Two Days)

Materials:

• A couple crackers for each student.(day 2)
• Drinking glasses and cups of water for each student.(day 1)
• Cracker lab sheet (day 2)
• Muscle Action in Digestion sheet (day 1)
• Animals Feeding Worksheet (day 1)

Objective:

• Students will describe three main ways animals get food.
• Students will explain the importance e of digestion.
• Students will tell the difference between a gastrovascular cavity and a digestive tract.

Alaska Content Standards:

• SCI A-10 Students will understand that living things are made up mostly of cells and that all life processes occur in Cells (Cells)
• SCI A-11 Students will understand that similar features are passed on by genes through reproduction (Heredity).
• SCI A-12 Students will distinguish the patterns of similarity and differences in the living world in order to understand the diversity of life and understand the theories that describe the importance of diversity for species and ecosystems.
• SCI A-13 Students will understand the theory of natural selection as an explanation for evidence of changes in life forms over time (Evolution and Natural Selection)
• SCI A-14 Students will understand the interdependence between living things and their environments; that living environments consists of individuals, populations, and communities; and that a small change in a portion of an environment may affect the entire environment (Interdependence);
• SCI A-15 Students will use science to understand and describe the local environment.
• SCI B-1 Students will use the processes of science: observing, classifying, measuring interpreting data, inferring, communicating, controlling variables, developing models and theories, hypothesizing, predicting, and experimenting;
• SCI- C-8 Students will understand that acceptance of a new idea depends upon supporting evidence and that new ideas that conflict with beliefs or common sense are often resisted.
• SCI- D-2 Students will understand that scientific innovations may affect our economy, safety, environment, health, and society and that these effects may be long or short term, positive or negative, and expected or unexpected;

Anticipatory Set: Set up a cup with some sort of particulate "food" floating in the water. Run the water through the filter and have the students explain what is happening. Show the students a picture of a whale's baleen. Explain how it is used to filter organisms from the water. Then show the students pictures of several different filter feeders and how they filter their food. 1, 2, 3, 4, 5, 6

Define Filter feeding.

The paragraph under Filter Feeding talks about these organisms, show a picture of each and describe it.

1. Sponges strain bacteria and protists and can not move around.
2. Barnacles collect food particles with their legs even though they do not move around. Their legs act as screens.
3. Mollusks, clams and oysters, use gills to strain food and do not move around.
4. Whales we already talked about. They move around.

Teacher Input: Ask students, How else do animals get food? (remind students of mosquitoes, and other insects) Divide the answers up into two groups, Consuming large Pieces of Food or Feeding on Fluids. Take feeding on fluids first.

Show the students a close-up of two mosquitoes. First Picture, Second Picture. Ask them to explain the difference between the two. Then show them a picture of a spider, humming bird, horsefly, bee, butterfly, and assassin bug. While showing them the pictures ask the students what all these animals have in common? After a little prodding the students should come up with the fact that all these animals feed on fluids which is the second type of feeding.

Teacher Modeling: The third type of feeding is much more common to the students. Consuming Large Pieces of Food. Explain that this method is the most common but animals differentiated by the types of solid foods they consume. What is the easiest way to tell what animals eat? Wait or give leading questions until they come up with teeth structure. Show them three different types of sculls and without knowing what animal they came out of have them tell what the animal most likely ate. Skull 1, Skull 2, Skull 3. Have the students read about the Komodo monitor lizard in red on P 117 and then predict which skull most closely resembles the Monitor Lizard.

Define: Herbivore, Carnivore, Omnivore.

Independent Practice: Give the standing on their head drinking exercise. Explain how some animals need to suck water up a great distance to there stomach, (giraffe) Have the students explain why it is important to be able to not rely on gravity during digestion. Can the students name any other animal that can drink water while its esophagus is in the direction of gravity?

Have the students complete the worksheet, Animals Feeding.

Check for Understanding: Refresh the students' memory on the types of feeding by showing three pictures, a filter feeder, a fluid feeder, and a large pieces of food feeder. Ask, "What happens inside an animal after food is obtained whether it is by filtering, fluids, or in chucks. Define digestion. Lead the student through a diagram of a simple digestive system. Key points:

• All animals secrete digestive enzymes, define Secrete, and Enzyme.
• Small simple organisms without a digestive tract need food to come very small, it must fit inside food vacuoles inside cells, sometimes digestive enzymes work inside these cells, (sponges)
• The simple digestive tract like this gastrovascular cavity allow for larger food particles,
• This space has only one opening
• Special secreting cells add enzymes inside the gastrovascular cavity.
• After digestion material not digested leaves through the mouth.
• Disadvantage, animal can not look for food again until digestion is complete.

Lead students through this more complicated system:

• Called a digestive tract, define digestive tract.
• Trace the path of food as it passes through the system and define Crop, Gizzard, and Anus along the way.

Lead students through this more complicated digestive tract. (this is a sheep but is similar to a moose)

• Four stomach chambers where other organisms help digest the food.
• Long intestines and a cecum to help digest the food.
• Here is what some of the parts do:
• Cecum - fiber that is hard to digest sits here and is slowly digested.
• Rumen - this is were a good deal of the fiber is digested. It is mixed with digestive enzymes, regurgitated, chewed again and swallowed over and over until it passes into the reticulum. Cow magnets are place here to catch metals that a cow may eat.
• The reticulum strains the food and reabsorbs some of the water.
• The omasum is where most of the digestion occurs.
• The abomasum is where food begins to form pellets and move through the small intestine were nutrients from the surrounding liquids is absorbed.

Guided Practice: Help students define Digestive tract, crop, gizzard, and Anus.

Closure: Have the students experience a little digestion themselves. Have them chew a cracker for an extended period of time. (Follow the instructions on the worksheet.

Independent Practice: Students should take the quiz over lesson 1.

Duration:

(2 periods) 30 minutes + 10-15 for Independent Practice (Could be longer if taken for homework).