Fish have been a part of the human diet for ages, but they also serve other roles for maintaining human health. Scientists are just beginning to discover some of these roles. If you protect the water, you protect the fish, the planet, and all its inhabitants.

Filthy Fish

Fish are a really healthy source of protein and special fats that help brain development and function. Due to human pollution, some fish may contain harmful chemicals, like mercury, which is primarily released from power plants that burn coal. How does mercury end up in fish? When mercury is released into the air from smokestacks, it falls to the ground and into the water. It is eaten by microscopic organisms. Then small fish eat the microorganisms, large fish eat the small fish, larger fish eat the large fish, and on up the food chain until it reaches humans. Through this process, called bioaccumulation, the levels of the pollutant get stronger and stronger. By the time it reaches humans, it's at high enough levels to be bad for health, especially for young, growing kids whose brains are still developing.

You can demonstrate this process by splitting your class up to represent various creatures in the food chain. A large chunk of the class will be microorganisms, fewer will be small fish, even fewer will be large fish, and one will be a human. Give each microorganism something to represent pollution. They only have one tiny bit of pollution — not bad — but what happens as they are eaten? The small fish need to eat many microorganisms to survive, so they should go tag the microorganisms they need to eat. How many bits of pollution do they have in their bodies now? Now the few large fish have to eat several small fish (along with the microorganisms they've eaten). How many bits of pollution do they end up with? Now the one person has to eat the large fish to survive (along with all of the bits of pollution). That one person gets a lot of pollution with her dinner.

Eat a Coral Reef

Coral reefs are the largest living structure on the planet, and they are one of the most threatened marine systems. The reefs are created by creatures called coral polyps. Polyps are tiny creatures that form a hard skeleton to protect their bodies. Polyps use plants to help them to make their skeleton. The skeletons of many polyps stick together and form a coral reef. Corals are living animals that eat, grow, and reproduce. This takes a long time; reefs only grow at about an inch a year. They also provide homes for many, many other species. Scientists speculate there could be another 1 to 8 million undiscovered species living in and around coral reefs! Since reefs support so many types of organisms, they may be key to finding new medicines. Many medicines are already created from creatures and plants that live in coral reefs. These new drugs may be possible cures for cancer, arthritis, bacterial infections, viruses, and more.

People have barely begun to understand how important coral reefs could be to human health, but they are being damaged in countless ways. Learn more about coral reefs by making a coral reef cake! You'll need:

Come up with ways to use your candies and other materials to represent the various features of a coral reef. With younger students, the teacher needs to be in charge of one large cake. Maybe have one child volunteer at a time help construct each inhabitant of the reef. For older students, you can have smaller cakes and divide the students into small groups to do the activity independently. Before the cake is frosted, cut it into squares so that candy creatures can hide inside the cracks. When you have completed your coral reef, ask the students to review and describe the different features you've included. Dish it up! Do they know what they're eating?