Key concepts

Have you ever wondered how predators such as wolves, lions and hawks are able to find their prey? And what can an animal do to keep from being a predator's dinner? To survive, some animals use camouflage so they can better blend in with their surroundings. In this science activity you'll be the hungry predator and you'll hunt for different colored candies. But it may not be as easy as it sounds—some of your prey will be camouflaged by their habitats. Will they be able to avoid your grasp? To find out, work up an appetite and go hunting for leftover candy!

Nature can be brutal. In the animal world if you're not a hunter, then you're likely being hunted. (And sometimes you're both the hunter and the hunted.) What do animals do to avoid being eaten? Some animals develop defense mechanisms (such as porcupine quills or armadillo armor), gross tastes on their bodies or even poisons. This pattern of animals developing strategies to survive occurs, thanks to adaptation—and it is a mechanism of evolution.

A common way that animals can avoid being eaten by a predator is by using an adaptation called camouflage, which is a set of colorings or markings on an animal that help it to blend in with its surroundings, or habitat, and prevent it from being recognized as potential prey. This increases its chance for survival. Different animals need to adapt to different habitats, and animals adapt in all kinds of interesting ways using camouflage. For example, katydids are insects that usually live in leafy trees, and many have adapted to that habitat by developing a green body shaped like a leaf. This helps them hide from predators such as birds, who might mistake them for less tasty leaves. Some species of octopuses, on the other hand, often change habitats on colorful coral reefs and have adapted a way of changing their skin to match their immediate environment.

• Six plastic bags
• Plain M&Ms, at least 10 of each color (At least two 1.69-ounce packages may be needed.)
• Skittles, at least 60 of each color (At least one 16-ounce package may be needed.)
• Metal pie tin or sturdy paper plate
• Timer or stopwatch
• Two to four volunteer "predators" who are up for devouring some M&Ms

• Count and place 10 M&Ms of each color into a plastic bag. This means you should have one plastic bag with 10 yellow, 10 blue, 10 green, 10 brown, 10 red and 10 orange M&Ms candies in it (making a total of 60 candies in the bag).
• Count and place 60 Skittles of each color into their own bags (making five separate bags each containing a separate color). This means you should have one plastic bag with 60 orange Skittles, one with 60 yellow candies, one with 60 green candies, one with 60 red candies and one with 60 purple Skittles. If you are short on time, you can skip preparing one or two of these bags.

• Explain to your two to four volunteer "predators" that they should pretend to be hungry M&Ms-feasting birds. They should make a "beak' using their pointer finger and thumb for collecting M&Ms. Explain that they'll have 20 seconds to use their beaks to quickly pick up M&Ms and put them in their other hand. To encourage the volunteers to be fast, tell them that when they are done with the activity, they can eat the same number of candies as they picked up. But they should not eat the candies until you are done with the activity.
• Also tell the volunteers that they should avoid picking up any Skittles candies, because Skittles make the M&Ms birds sick. The M&Ms are their prey, and the Skittles represent the habitat in which the M&Ms live—and try to use as camouflage. How do you think the Skittles habitat will work to camouflage the different colored M&Ms prey?
• After explaining these rules, pour one prepared bag of Skittles into a metal pie tin or sturdy paper plate. Mix in the prepared bag of M&Ms. Put the pie tin in the middle of your group of M&Ms bird volunteers. Make sure everyone can reach the pie tin. Which M&Ms are the best camouflaged in your pie tin?
• Set your timer for 20 seconds. Say "Go!" and start the timer. When the timer beeps, make sure everyone stops picking up M&Ms.
• Count the number of each M&Ms color that each person collected. Also count any Skittles that were picked up. Which M&M color was the least-picked one?  What do you think this has to do with camouflage?
• Put all of the M&Ms back in the bag you prepared them in (including M&Ms that people picked). Remove the Skittles you used for the habitat (by pouring them off the pie tin).
• Repeat the 20-second M&M hunt with the other prepared bags of Skittles until you have tested each Skittles habitat (separately) with the M&Ms. For each Skittles habitat, which M&M color was the least-picked one? Can you explain what this has to do with camouflage?
Extra: Adaptation and evolution happen over several generations. Try testing this by picking one colored Skittles habitat and mixing your prepared bag of M&Ms with it in the pie tin. After a 20-second round of M&M predation, as described in this activity, double the number of M&Ms that are left by adding a colored M&M to match the color of each remaining M&Ms. For instance, if there are four red and two brown M&Ms, then add four more red and two more brown M&Ms. Then repeat another round of predation. How many rounds does it take to remove all of the M&Ms of one color?
Extra: Find pictures of different camouflaged animals, such as a katydid that looks like a leaf on a tree branch or an octopus that is blending in with its surroundings. (For some examples, look at the links in the "More to Explore" section on the next page.) After finding several pictures of different camouflaged animals, show them to some volunteers and time how long it takes the volunteers to spot each animal. Do some camouflage techniques work better than others, causing the volunteers to take longer to spot the animal?
Extra: You could try repeating this activity using different types of candy. How easy is it for M&Ms birds to catch their prey when the habitat is made using candies of a different shape, such as Nerds  or other candies that are both different in shape and multicolored, like candy corns?

Observations and results
Did the M&Ms that were the same color as their habitat get picked less frequently? Did the brown M&Ms get picked less frequently in the purple Skittles habitat than any other M&M's color?

At a glance, it is difficult to tell M&Ms and Skittles apart. Skittles are slightly different in shape from M&Ms, but their yellow, green, red and orange colors are very similar. So if you tell someone to avoid picking Skittles (the habitat color), they're probably less likely to pick M&Ms that are the same color as those surrounding Skittles. Those M&Ms "prey" are being camouflaged by the same-colored (and similarly shaped) Skittles habitat. Consequently, in the yellow Skittles habitat, the yellow M&Ms should have been picked less often than any other variety, and the same goes for the green, red and orange Skittles habitats—the same-colored M&Ms should have been picked the least often. Also, purple Skittles are somewhat similar in color to brown M&Ms, so the brown ones should have been the color least often picked in the purple Skittles habitat. Blue M&Ms should have been picked at about the same rate in each habitat because there are no Skittles that are very close in color.

When you are done with your experiment, you can let the volunteers eat the candies, if they want to.

More to explore
Photos of Ecological Adaptations #1, from W. P. Armstrong, Palomar College
What's It Like Where You Live?, from Missouri Botanical Garden
Charles Darwin and Evolution: What Is Evolution?, from S. Montgomery, Christ's College Cambridge
M&M Survival Challenge, from Science Buddies

This activity brought to you in partnership with Science Buddies