By Susan Hershberger
Have you ever eaten algae … or tasted seaweed snacks or rice wrapped in sushi nori? If your answer is yes, you have eaten algae without doubt!
Sometimes, however, the algae we eat are not so obvious. If you have had cream, ice cream, cheese sauce, cherry pie, or deli meat, you have likely eaten algae. This is because carrageenan, an extract from algae, is used as a food thickener. For example, it makes school- and store-bought chocolate milk creamy and also keeps the chocolate from settling to the bottom of the carton.
Algae are important, even if you do not eat the foods listed above. When you eat fish (or other organisms) that eat algae or grass, the energy you get was originally captured from the sun and flowed to your plate through food webs. Here is how:
- In ocean water, algae use carbon dioxide and sunlight to make their own food and grow. Then small crustaceans called krill eat the algae. Next, fish such as herring eat the krill. Later, larger fish, such as salmon, eat the herring … and last but not least, people eat the larger fish.
- On land, grasses use carbon dioxide and water with sunlight to grow. A grasshopper eats the grass, and then a frog or mouse chews on the grasshopper. Next, a snake swallows the mouse or frog. Later, a hawk or a coyote chomps the snake. Through this series of interconnected eating, the energy used by grass to make its own food reaches other animals and birds that depend on grass or other smaller living things. Similarly, cows eat grass. Later, young cows (calves) and people drink the milk that cows produce. So when you drink milk, your body uses the energy that was originally captured from the sun by the grass.
Cows and burps
Cows have a complex digestive system, with many biochemical reactions happening inside their stomachs. When cows digest grass, they burp and release a gas called methane. Methane is called a greenhouse gas, because it traps heat within the earth’s atmosphere, similar to the way a greenhouse captures heat from the sun to help plants grow. But when our atmosphere keeps getting warmer, it is bad for all of us.
About 30 percent of all methane emissions comes from burning petroleum fuels for transportation and electricity. But it might surprise you to know that another 7 percent of the world’s methane comes from cows burping! That means that we can reduce these emissions by biking and walking more (instead of riding in gas-powered cars) … and also by helping cows burp less!
As for the methane emission from cows, researchers and farmers have observed that when Asparagopsis taxiformis, a red alga, is added to cows’ feed, they release fewer burps—by more than 60%. This means cows will only release 4 burps in place of 10! Adding tiny amounts of algae to cows’ regular diets does not harm them or change the amount or flavor of the milk they produce. It is kind of like feeding cows health supplements. Researchers need more data to know exactly how algae supplements work, and how cows everywhere can benefit from them.
In the future, when you drink either plain or chocolate milk, you may be consuming energy from the sun captured by algae, as well as by grass. That kind of milk would be better for the environment, too. Fewer cow burps means less methane and a cleaner earth.
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Susan Hershberger is Director of the Center for Chemistry Education in the Department of Chemistry and Biochemistry at Miami University in Oxford, Ohio.