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4H EEX 01 Florida 4-H Environmental Education Activities GOOBER ETUS Grade Level Sunshine State 3-8 Science SC. G. 1. 2. 1. SC. F. 2. 3. 3. Mathematics MA. D. 1. 3. 2. MA. A. 3. 3. 3. Major Instructional Goal Associated Concepts Educational/ Instructional Objectives To help students understand the relationships that exist between predator and prey populations which keep them in homeostasis. A. B. C. D. Interdependence Populations Habitat Predator-Prey Relationships E. Adaptation F. Extinction G. Homeostasis Upon completion of this activity, students should be able to: 1. Name three ways in which prey may be protected. 2. Explain the advantages to a predator if it preys on more than one species. 3. Give two examples of how a population could become ex tinct. 4. Construct a graph depicting the change in both predator and prey population levels over time and give reasons explaining the shape of the curve for one of the populations. 5. Define homeostasis and state how the predator-prey popula tions maintain a dynamic equilibrium. Predation in its broadest sense can be viewed as one organism consuming The Institute of Food and Agricultural Sciences is an Equal Employment Opportunity - Affirmative Action Employer authorized to provide research, educational information and other services only to individuals and institutions that function without regard to race, color, sex, age, handicap or national origin. COOPERATIVE EXTENSION WORK IN AGRICULTURE, FAMILY AND CONSUMER SCIENCES, SEA GRANT AND 4-H YOUTH, STATE OF FLORIDA, IFAS, UNIVERSITY OF FLORIDA, U.S. DEPARTMENT OF AGRICULTURE, AND BOARDS OF COUNTY COMMISSIONERS COOPERATING. The 4-H name and emblem is Protected under 18 U.S.C. 707. 1 4H EEX 01 Florida 4-H Environmental Education Activities another organism as an energy source. The prey is the individual consumed. Predation represents a direct and often complex interaction and may help regulate both the predator’s and the prey’s population levels. For this activity, the use will be limited to animals hunting other animals. Background Information Given time, a population generally reaches a balance of numbers based largely on the carrying capacity of the environment, relationships within the population and outside factors. One factor operating outside the population may be predation. Usually the population size of the prey is affected by the population size of the predator in an inverse relationship. Under controlled laboratory conditions, situations have been observed in which both the predator and the prey may be eliminated. In natural systems, extinction of populations caused by predation is much more rare. Extinction of an organism is complicated by the fact that both predator and prey are part of a complex food web, immigration/emigration occurs, environmental factors and behaviors effect interpopulation dynamics. The long range trend of such predator-prey relationships would be a system of checks and balances between the two populations. For example, the numbers of some predators may depend on the abundance of availability of their prey, and predation may regulate the population of prey. If predators cannot find and consume a particular prey species due to its scarcity or another factor, then the predator may shift to other prey species in order to conserve energy expenditures. This allows the prey population to increase energy expenditures. This allows the prey population to increase and the cycle repeats. This dynamic equilibrium in which neither predator nor prey populations are eliminated is an example of homeostasis. Extinction may occur but almost always results from new factors impinging on the existing natural system. Habitat destruction is the most common cause. Introduction of alien species which outcompete, cause a fatal disease, or prey on native species, also have decimated many species, especially in isolated ecosystems. Market hunting and poaching, if not regulated, can extirpate a species from affected areas. Various types of pollution may also result in the extinction of certain species. Both prey and predator species evolve adaptations that allow them to escape, capture or become more efficient hunters respectively. Camouflage, increased prowess, or speed adaptive behavior and morphological characteristics are examples. Predation, as an agent of natural selection, may help in the development of the many desirable ‘survival’ traits possessed by animals. 2 4H EEX 01 Florida 4-H Environmental Education Activities Activity A. B. Introduction 1. Learning Site – any edge community of about 100 square yards containing separate areas of short and taller vegetation. This area should be free of poisonous plants or other hazards. 2. Materials – Peanuts in the shell (100 per group of 10-15 students), graph paper, a chalkboard and chalk to record the date and illustrate the concepts. 3. Preparation by Instructor – Randomly scatter the peanuts throughout the edge community before the participants arrive. 4. Critical Vocabulary – Predator, Prey, Population, Protective Coloration, Habitat, Adaptation, Extinction. 5. References : a. Ecology Text b. Gilbert, N., (Frazer, S., D. Gutierez, A.P., Jones R.E.) Ecological Relationships c. Camouflage: A CWES activity d. Sticklers : An OBIS activity Directions for Actual Activity 1. 3 Focus – 10-15 minutes. Introduce the group to the idea of studying a population which recently immigrated to the area. Describe the populations as invertebrates having a beige exoskeleton without giving the animal away as a peanut. Discuss the adaptations the ‘Goober Etus’ have in order to help protect them from predation (camouflage and exoskeleton are two of many possibilities). Describe the habitat they live in and any other pertinent points to convince the students the populations is worth investigating. Briefly explain that the group is to observe the population in its habitat and record its behavior. The group can be told that humans can be predators and ask if anyone would wish to try one (this will increase the excitement level). Take the group to the site and demonstrate capturing the ‘Goober Etus’. After it is revealed to be a peanut, explain that they will play a game in which they will be the predators. 4H EEX 01 Florida 4-H Environmental Education Activities 4 2. The Activity – 15 min. Introduce the concepts of predator and prey and explain the rules of the game as follows: Predators will be given one minute to hunt. They are to collect as many peanuts as they can. This one minute time span represents a long time period such as one or two weeks. If a predator fails to find any food, he/she will starve to death. This game will be repeated four times with only successful predators participating. Data on the number of predators and prey surviving after each hunt should be recorded. Plot the data for both predator and prey populations against time on the same graph. This way the students will be able to see the relationship that exists between predator and prey populations. With younger students, piles of peanuts or pieces of paper representing predators could be used in place of graphs. 3. Synthesizing Strategy – Reinforce the concepts illustrated through the activity. Discuss why scientists use graphs in their studies (showing relationships between two variables, noting changes in rate, making predictions). Through using the graph, have the students describe the relationships between predator and prey in this simulation. Contrast it to real relationships between predatorprey populations. The following points should be discussed and illustrated through examples: population inputs, individuals that fall victim to predation, predators utilizing more than one food source, dynamic equilibrium maintained between predator and prey population, extinction and major causes. Many relationships or concepts could be a major topic of focus from this activity. The important idea is to extend the predator-prey model illustrated by the game to that negatively. That humans have impact on this relationship can also be a topic of discussion/investigation. a. Did the color of ‘Goober Etus’ blend with its environment? If so, how? b. Could this color(s) be used as protection from predators? c. As the game proceeds, what happens to the predator and prey population? What are the three factors that account for more prey being caught in the beginning than toward the end? 4H EEX 01 Florida 4-H Environmental Education Activities d. e. f. 4. (more prey, more predators, and easier to find) How does this correspond to actual predator-prey relationships? If the game continued, do you think that the ‘Goober Etus’ population will become extinct? Why or why not? Will the predator population become extinct? In a real situation, like wolves and deer, why do both populations continue to coexist? How does the deer population control the wolf population and vice versa? What are two reasons why populations be come extinct? (habitat destruction, market hunting by man, introduction of new blight or disease, and introduction of new species which will outcompete the original one for its niche.) What role does man play in extinction? Suggestions on Time and Problems – The total activity can be completed within one hour. The activity itself, however, is relatively short. You may want to make the peanuts harder to find for older students. The number of time periods is relative depending upon population sizes and time. However, it would be best to stop the hunts before either population level reaches zero. The study and graph showing the population fluctuations between the hare and the lynx would help show how a dynamic between predator and prey populations is established and maintained. This may be difficult for younger students to conceptualize. 5