How Many Penguins Does It Take?
Studying carrying capacity and limiting factors

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Hook
Have you ever wondered why animal population numbers just don’t explode and keep going? Populations change over time. Deaths, births, immigrations, and emigrations all affect how many individuals are left in a population. Other factors--such as food, water, shelter, space, disease--dictate population numbers. These are called limiting factors. They are limiting because they affect whether or not the population will increase or decrease. Carrying capacity is the number of organisms an ecosystem can hold long-term without any damage to that ecosystem. For example, let’s say that you have 100 acres of woods behind your house. That 100 acres can only hold a certain number of squirrels. There are only a certain number of nuts to go around. Once those nuts are gone, the squirrels must either find another home, or they will die of starvation. So, over time, you’ll find that the squirrel population stays at an average number that the woods can support--no more, no less. And that is carrying capacity.

Materials
This activity sheet 1 baggie (represents your penguin stomach) with your name clearly marked on it

Procedure
You are a penguin. The baggie you hold is your stomach. Please label with your name. The goal of this activity is to pick up as many cards as possible from the designated area, until all cards are gone. The cards represent penguin food. Lay your baggie down at the start line. When the teacher says, “Go!”, you may run and pick up one card at a time and bring back to your baggie. Repeat until all cards are gone. Add up the numbers on your cards. Make sure you notice the difference between the 1 and .10 cards. What was your total?___________ This represents the number of pounds of food you gathered. A penguin eats about 6.6 lbs. of food per day. Did you reach this amount? __________

Discussions Questions/Extensions ......
1) Was there any evidence of sickness or injury preventing our volunteer penguins from getting enough food? What might eventually happen to them?

2) Would the parent penguin keep the gathered food for himself, or would he give it to the baby penguin? Why?

3) Look at the following graph. What does K represent?

4) Would K be exactly the same all of the time, or is it more of an average?

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