EXPEDITION PANAMA: Champion Chompers
Leafcutter ants have been called "the world's first farmers." For millions of years, they have been cutting up leaves from the tropical forest and carrying the pieces to fungus gardens grown in their nests. The ants use the leaves to cultivate the fungus, which in turn provides a home, nutrients and jobs for many different ants in the species. After a quick climb to the canopy, join Frontiers on the floor of the rain forest.
Related Shows and Activities
Activity 1: Weightlifting World Record
Activity 2: The Ants Go Marching
What's Up in the Rainforest
rain forest ecology
RELATED SHOWS AND ACTIVITIES
- About All You Can Eat (Show 502): "Mushroom Mania"
- Science 911 (Show 404): "Panama Protection Racket"
- Show 202: "Ants That Take Slaves"
- Show 102: "Test-Tube Truffles"
ACTIVITY 1: WEIGHTLIFTING WORLD RECORD
Tropical leafcutter ants are champion weight lifters and play a significant role in the rain forest ecosystem. One experiment suggests the ants cut as much as 20% of the foliage from trees. The ants do this by cutting leaves into manageable bits and carrying them back to their fungus gardens. The ants don't eat the leaves, but they add the leaves to the fungus (think of a nice, organic mulch enriching the soil). The fungus grows on the leaves, consuming them in the process. Then the ants eat parts of the fungus. It's a great deal for all involved!
As you see on Frontiers, even though the ants are small, they are able to carry pieces of leaves that are much larger than their body size. But small size also has its limitations. An ant could never start a fire to keep warm, let alone get close enough to feed it fuel. To gain a new understanding of what it means to "be the right size," try these mathematical problems.
Use graphing to compare weightlifting ability of ants and humans.
Scientists have found that some ants can lift more than ten times their body weight over their heads. Multiply by ten to find out how human weight lifters compare with the champions of the insect world.
- Olympic weight lifters are divided into different classes by body weight. Look up records for different classes in the Guinness Book of Records or on the Internet (http://www.usaw.org).
- Plot the records for the different classes on a graph. Use the horizontal axis (x) for weight class and the vertical axis (y) for the world record of weight lifted for each class. (Use the record for total amount of weight lifted rather than individual events like clean-and-jerk or snatch.)
- For each weight class, plot the amount of weight champions should be able to lift if they could lift ten times their weight.
- How far off was each weight class from the amount predicted, using the ant's formula?
- Why do you think ants can lift so much more (relative to their weight) than humans?
- Which weight class exhibits the greatest amount of weight lifted relative to body weight? Can you use this to argue that one weight class is performing at a higher level than others?
- If you could lift an object ten times your weight, how much would the object weigh? Can you think of an object that weighs that amount?
- If a forest loses 20% of its foliage, what might be the implications?
The mathematics behind size and its impact on life are much more complicated than the simple formula used above. Life's Devices by Steven Vogel and On Size and Life by Thomas A. McMahon and John Tyler Bonner provide more information on complex size and scale relationships.
ACTIVITY 2: THE ANTS GO MARCHING...
Ants produce pheromones to make invisible chemical trails for other ants to follow. You can observe ants at work outdoors. Crumble a cookie or other ant goodie. Then watch the ants make a trail back to the nest to communicate the location of the treat. What happens when you cover the trail with a leaf or piece of plastic?
Leafcutter ants and fungi are co-dependent; one cannot exist without the other. Investigate the roles ants and fungi play in the forest ecology.
Leafcutter ants exist only in the New World and mostly in the tropics. Why might this be so?
Why can ants fall from great heights, yet remain unhurt?
WHAT'S UP IN THE RAIN FOREST?
The tropical rain forest is a region of incredible biodiversity.
Scientists right now are debating the issue of how rain forests evolved with such diversity. Can you theorize why life in the tropics is more diverse than life in temperate zones?
Why should we care about biodiversity?
The great variety of species in the rain forest may contain cures for illnesses, or genes that one day can be used to help engineer insect- and disease-resistant crops. It's estimated that one-fourth of all medicines are derived from rain forest plants. Can you find examples of drugs derived from plants (digitalis from foxglove, for example)?
Do you know anyone who uses plant remedies?
Some people use aloe to relieve the pain of burns or tea to soothe nerves. Both are ethnobotanical remedies for common maladies. Read "The Enthobotanical Approach to Drug Discovery" in the June 1994 issue of Scientific American.
Life at the top.
Illustrate the levels of the rain forest, from forest floor to the canopy. Where do most species live?
Scientific American Frontiers
Fall 1990 to Spring 2000
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