Predator/Prey
Environmental Education Lesson
Edwards YMCA Camp and Conference Center
Summary
Everyday it is a constant battle for animals to survive. They need to find food and avoid being eaten. This relationship between predator and prey intertwines into a complex food web. They play an important role in keeping populations near the carrying capacity. Predator and prey have special adaptations to help them compete for resources they need in their ecosystem. Students can get a first hand experience of this predator prey relationship by demonstrating how food chains are formed, examining animals adaptations and acting out the relationship of foxes and rabbits.
Usage
Grade level: K-8th
Objectives
Upon completion of this lesson students will:
- Develop an understanding of food web and how producers, consumers and decomposers relate.
- Learn at least 3 different adaptations that predator and prey species have to help them survive.
- Understand the relationships that predator and prey have, through dynamic populations, carrying capacity and limiting factors.
Materials
·Spool of string or rope
·Paper
·Crayons, markers, colored pencils etc.
·Bandanas or fabric for rabbits tail
·Cones to mark animal habitat
·Graph and markers to chart animal populations
Introduction
With in an ecosystem there are many species and each play an important role in keeping the system balance. One way to divide up the species is by how they get their food, if they make it (producers) or if they need to find it (consumers) or if they breakdown dead material (decomposers). The relationship between these species is a food chain or web demonstrating who eat who and the flow of energy. Individual interactions that come out of the food web are that of predator and prey. Predators and prey each have special adaptations to help catch their food or not become food. The competition between the two acts as a check and balance for the ecosystem's population.
Warm-up Activities
The Web of Life
The web of life is to demonstrate how species are depended on one another. If one species is removed from the ecosystem it is going to have an affect on all the other species further down the food chain. This is also an opportunity to introduce the terms producer, consumer and decomposer. Have to students sit or stand in a circle. Take the end of the string and have the first student hold on to it, they represent the sun, the source of all energy. Begin unrolling the sting and have another students pick a producer and the following student a primary consumer, then a secondary consumer, each holding onto the string. A decomposer can be added to break down dead material and create rich soil for the producer the use. The whole sequence starts over again with producers continuing until each student is holding a section of the web.
After the food web is completed see if the students can predict what will happen if just one species is removed from the web. Pick a species and a reason why that species was lost from the ecosystem. For example a drought causing a shortage of food or a new housing development taking away habitat. Once one species is removed demonstrate how the other species are going to be effected and break apart the food web. As John Muir said "when we try to pick out anything by itself we find that it hitched to everything else in the universe." As each species is taken out of the web have the student let go of the string to show the web falling apart.
Activities
The Ultimate Predator or Prey
Every species have specific adaptations that help them to live in their habitat. Predator and prey, as groups, have general adaptations to help them survive. Start off with brainstorm the adaptation that predators and prey have to help them survive. After the students have an understanding of the difference between predator and prey adaptations have them create their own species. Have the students draw a picture of what they think the best predator or prey would be and with what special features it will have to help the animal survive.
Predator adaptations:
- Eyes in the front of their head "Eyes in the front they like to hunt" (making it easier for judging distance and better depth perception
- Sharp claws, beak or teeth (used like a knife and fork for catching prey and tearing the meat)
- Stingers or venom (assist in killing prey)
- Keen hearing (detection of prey at long distances)
- The ability to detect vibration or inferred (feel the prey move or the heat they give off)
- Speed (the ability to out run prey for short distances)
Prey adaptations:
- Eyes to the side of their head "Eyes on the side they like to hide" (easier to see the whole area around them)
- Camouflage or disguise (blending with habitat or looking like another object)
- Bright and distinctive colors (a sign of being poisonous or dangerous)
- Mimicry (looking like a poisonous species but is not one)
- Inaccessibility (living in places where predator do not fit, for example in borrows)
- Defense mechanisms (ways of warding off predators, for example spines, bad taste, antlers, shells, unpleasant smells)
- Herds (protection through numbers)
Population Dynamics: Rabbits vs. Foxes
Predator and prey can not survive without the other, their populations are directly related. In this activity their relationship is illustrated using foxes, rabbits and clover.
Playing field: place 4 cones in a rectangle approximately 30'x 50' one end being the rabbits' burrow the other is the clover patch and between the cones is the fox's territory.
Players: Divide the students up into the ratio of 1 fox, 2 rabbits, and 3 clovers. Rabbits get a bandana or piece of fabric to represent a tail. It works well to have it tucked a little ways into a pocket but where the fox can still crab it and pull it off.
 Clover: hang out in the clover patch until a rabbit comes and "eats" them if they make it back to the rabbit burrow they will be a rabbit in the next round.
Rabbit: Try to run from their borrow to the clover patch and pick up a clover. Then run back to the rabbit borrow holding hands or linking arms with the clover. The foxes are trying to catch the rabbits as they run between the burrow and clover patch. If they make it back they stay as rabbits if they get caught by a fox, losing their tail, they become foxes for the next round. If a rabbit does not get any clover they die and become clover for the next round.
Fox: Need at least one rabbit per round to survive, they catch a rabbit by pulling off its tail. If they eat they stay a fox for the next round, if they do not catch a rabbit they will die of starvation and be a clover for the next round.
Play 5-10 rounds to see how the population of each species fluctuation in relation to the others. The population numbers can be graphed to have a visual aid for discussion after the game is complete. Through each round there will be a change in population due to the fact that not everyone is able to get the resources they need. If the fox population is high and the rabbit population is low, the rabbits will be able to get plenty of clover increasing their numbers for the next round where as fox fatality will be higher due to starvation and decrease for the next round. This is a dynamic population and is fluctuating around the equilibrium known as carrying capacity. An ecosystem can only hold so many of each species before there are not enough resources to go around.
Finding food is not the only thing animals have to worry about, there are many different limiting factors. These factors hinder population growth just like the lake of food. Variations came be made to the game to illustrate how different circumstances effect the populations. Some possibilities are half the clover populations died due to drought, a hunting season for either foxes or rabbits, disease killing off part of a one of the species populations.
Wrap-Up
Students have now had a chance to understand special adaptations that predators and prey have in order to survive and see what happens to a population as species interact to find food and fight for survival. With the web of life it becomes apparent that if a food chain is disturbed it causes repercussions further down the chain. With the specific food chain of clover, rabbits and foxes students should now understand the population numbers do not stay constant. When one population changes it effects the rest of the populations in the system. Predator and prey have a cyclical cycle that they travel through. One population is increasing and the other is decreasing and they are continually changing places. This continuously cycles around the carrying capacity, the population which the ecosystem can support. This can change because of limiting factors. Outside forces that inhibit population growth.
Possible discussion questions:
What caused the populations to fluctuate?
How to predators and prey interact?
What role/affect do humans have on a food chain?
What are limiting factors and how do they affect a population?
How do adaptations evolve?
How can humans help animal populations?
Where do humans fit in the food chain?
Can pollutants be passed through a food chain?
How do adaptations help an animal?
What happens when something is removed from a food chain?
FACTS AND INFORMATION
- Producers make there own food, such as plants.
- Consumers need to find food, primary consumers are herbivores and secondary consumers and above are carnivores.
- Adaptations are specific modification that a species to better suits its environment.
- Carrying capacity is the maximum population of a species that a habitat can support over time.
- Limiting factor is a outside force that limits the growth, abundance, or distribution of a population.
Eastern Cottontail (Sylvilagus floriclanus)
- Eastern cottontail is the most common rabbit in North America.
- They are herbivores mainly eating herbaceous plants like grass and clover but in the winter eat wood plants, bark and buds
- There habitat is forest, meadows and farmland
- Cottontails can leap up to 15ft
- Rabbits eat their own scat one time to get more nutrients out of it.
- A female rabbit can be ready to mate a few hours after giving birth.
- Few rabbits live more than a year.
Red Fox (Vulpes vulpes)
- Foxes are omnivores eating rodents, birds and fruit.
- Their habitat is forests, prairies, farmland and near marshes.
- A red fox can be as tall as 16 inches, 3.5 feet long and weigh up to 15 pounds.
- The red foxes are the most widespread animal in the wild dog family.
- Fox dens have many exits for quick and easy escape from danger.
- Foxes have such sensitive ears that they can her an earthworm moving in the grass or a mouse squeal up to 150 yards away.
- The red foxes territory range is 2 miles2.
Red Clover (Trifolium partens)
- Red clover was introduced from Europe.
- It is found in meadow, lawns, prairies, roadsides and forest edges.
- Clover grows between 6-16 inches tall.
- It flowers from May to September.
Resources
Kochacnoff, Peggy. A Field Guide to Nearby Nature Fields and Woods of Midwest and East Coast. Mountain Press Publishing Company: Missoula Montana. 1994.
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