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Enrichment 8-1: Teacher Activity Notes

Predator-Prey Relationships

PLAN

Summary

Students observe predation by constructing a model environment consisting of fruit flies and carnivorous plants inside a plastic bottle.

Objectives

Students:

\checkmark explain the terms predator and prey and give examples of each.

\checkmark observe the interactions between two different species.

Student Materials

Per student

  • Activity Guide
  • Activity Report

Per group

  • 2 two-liter plastic bottles
  • Cutting tool (scissors, utility knife, or single-edged razor blade with safety holder)
  • 1-3 carnivorous plants, such as Venus's-flytraps
  • Potting soil (peat)
  • Large sharp needle or push pin

Per class

  • 1-2 containers of breeding fruit flies
  • Waterproof tape
  • Clay

Teacher Materials

  • Activity Report Answer Key

Advance Preparation

Carnivorous plants can be purchased from most biological supply houses as well as from many nurseries.

Fruit flies can be purchased through a biological supply company or you can breed them yourself. The following are two sources of plants and fruit flies.

Carolina Biological Supply Company, 2700 York Rd., Burlington, NC, 27215. Call 1-800-227-1150.

Etgen's Science Stuff, 3600 Whitney Ave., Sacramento, CA 95821.

Phone: (916) 972-1871.

To breed your own fruit flies you will need to start 3 to 6 weeks prior to this activity to ensure that you have a large enough population. See Project 2: Population Boom or Bust on TE p. 217 for full details on starting your own fruit fly population.

Caution: Refer students to safety rules.

Depending upon the needs of your students, an adult helper could be brought in to assist students with cutting the bottles during class. Another option is to cut the bottles yourself before class.

Estimated Time

One 50-minute period to set up the model environments

Allow a few minutes over several days for students to make observations.

Interdisciplinary Connection

Language Arts Students may write a thorough description of the project in a report.

IMPLEMENT

Introduce Enrichment 8-1 by reviewing with students the difference between predator and prey using pages 47-54 of the text for guidance. Ask students to give examples from their personal experiences with predator-prey relationships. For example, students may have observed cats killing and eating mice or birds.

Steps 1-8 Have students work in groups to set up the model environments as explained in the Student Activity Guide. The illustrations should help students construct the environments without your assistance. Make sure the models are kept moist.

Steps 9-10 Check that students have developed and written hypotheses and a rationale for them. Have students observe their model environment several times during the day or at a certain time each day for a week. You may want them to record their observations and drawings in a data book. Observations can also be recorded as written notes, drawings, photos, or videotapes. Encourage students to think about and devise ways to present data in graph form.

Communication skills can be developed through writing a description of the project. Students could collaborate to put together a booklet or a poster board display of their results. These summaries could be the nucleus of a class or school presentation.

Conclude Enrichment 8-1 by discussing the questions on the Activity Report. You may wish to assign the questions as written class work or homework.

Extend Enrichment 8-1 by

  • Having students investigate interactions between other predators and prey. Other possibilities for predators could include praying mantises, spiders, small frogs, snakes, or lizards. These specimens could be captured in the wild or purchased from local pet stores or biological supply houses. Other possibilities for prey could include houseflies, mealworms, and mice. Depending on where you are located, you may have to be careful of poisonous spiders, snakes, and/or lizards. Students should be cautioned not to pick up strange animals without adult supervision.
  • Having students create or design different environments to observe predator-prey relationships. For example, students could use clear tubing to connect a fruit fly breeder container to a container housing a carnivorous plant or animal. Or they could use the tubing to connect a container housing a carnivorous plant with one containing an animal predator. Students could also connect one fruit fly breeder container to three or four predator containers. (See Project #2: Population Boom or Bust on TE p. 217 for directions and illustrations on how to build a fruit fly population.)
  • Having students investigate the effects of changes in environmental conditions, such as temperature, amount and estimated time of light, and amount of water. Students could also explore the relationship between the number of predators and prey under given environmental conditions.

ASSESS

Use the model environments, along with student observations and drawings, to assess if students can

\checkmark explain how to provide the necessary resources for the survival of both species.

\checkmark describe the interactions between the predator and its prey.

\checkmark define the terms predator and prey.

\checkmark explain the importance of predator-prey relationships in the natural environment.

Enrichment 8-1: Predator-Prey Relationships – Activity Report Answer Key

  • Sample answers to these questions will be provided upon request. Please send an email to teachers-requests@ck12.org to request sample answers.
  1. What do you think will happen? Why?
  2. Which organism is the predator? Which organism is the prey? Explain your answers.
  3. Can one organism live without the other? How could you find out?
  4. Why do you think predator-prey relationships are a necessary part of our environment?

Enrichment 8-1 Activity Guide: Predator-Prey Relationships (Student Reproducible)

Introduction

One type of interaction between species is a predator-prey relationship. In this situation, one organism usually eats another. The organism that “wins” is called the predator and the organism that “loses” is called the prey. In this activity, you will construct a model environment using plastic bottles to observe the predator-prey relationship between a carnivorous plant and fruit flies.

Materials

  • Activity Report
  • Safety goggles
  • 2 two-liter plastic bottles
  • Cutting tool (scissors, utility knife, or Single-edged razor blade with safety holder)
  • 1-3 carnivorous plants, such as Venus's-flytraps.
  • Potting soil (peat)
  • Large sharp needle or push pin
  • 1-2 containers of breeding fruit flies
  • Waterproof tape
  • Clay

Caution: Follow the safety rules when using cutting instruments. Remember to wear safety goggles when cutting.

Procedure

Step 1 If necessary, remove the label and base from each of the two plastic bottles. Rinse and dry the bottles thoroughly.

Step 2 Cut the two plastic bottles as shown in the picture. Be sure to make the cut on parts Band C so the curve of the bottle is included on each.

Step 3 Slide part A over part B as shown in the picture below. It may help to tape these parts together with waterproof tape.

Step 4 Using the potting soil, plant the carnivorous plant on top of part B as shown below.

Step 5 Tape part C on the top of part A. Your model environment should now look like this:

Step 6 Using a needle or a push pin, poke small holes into part C to allow air to enter, but not large enough to allow flies to escape. Also, poke holes on the sides of part B to allow the soil to drain.

Caution: Be very careful when using a sharp instrument.

Step 7 Select one or two food containers from your mature fruit-fly breeder that contain(s) the fruit flies. Place the food container(s) into the base. Fit part B snugly over the food containers and into the base. If desired, seal with tape.

Step 8 Be sure to keep the environment moist and to make any needed adjustments to the environment.

Step 9 Write down your hypothesis as to which organism is the predator and which is the prey. Give reasons for your answers on your Activity Report.

Step 10 Observe the interactions between the carnivorous plant and the fruit flies. Record your observations and include sketches or photos as appropriate.

Enrichment 8-1 Activity Report: Predator-Prey Relationships (Student Reproducible)

1. What do you think will happen? Why?

2. Which organism is the predator? Which organism is the prey? Explain your answers.

3. Can one organism live without the other? How could you find out?

4. Why do you think predator-prey relationships are a necessary part of our environment?

Image Attributions

Description

Authors:

Grades:

6 , 7 , 8

Date Created:

Feb 23, 2012

Last Modified:

Feb 23, 2012
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