Science ideas for young children Part 10 – Wild wacky water critters
Teach young children about science by playing in the river! The critters in a creek, pond or lake can give you an idea about how clean or polluted the water is.
This is the 10th article in a series on science activities about the natural world that anyone can conduct with children. Michigan State University Extension recommends this be done within a family, in a day-care setting, as part of school activities, a 4-H Club or with any group working with young children.
Children are fascinated by creepy crawly critters. Many people are surprised by the number of these creatures you can find in the water. Many of these critters are insects, but not all of them.
Catching the critters – With more than 20 years of looking at “water bugs” I have found a creek or lake without any life only a few times. If you have a creek, ditch, pond or lake near you, you probably will find some of these “bugs.” Go into the water with boots, waders or old tennis shoes and a net. Try to get into the parts of the water around logs, big rocks, gravel and plants. Areas where the water undercuts the stream bank are good too; especially where roots are dangling down. Try to get leaves and sticks, but not mud and sand. This can be very difficult, but try your best.
After you catch the critters in your net, dump them into a white tray with a little water. Styrofoam takeout trays work great for this. Often a local restaurant will give you the trays for free if you explain you are using them for an educational activity. Then use plastic spoons to move the “bugs” from the tray with the leaves and sticks to a tray with clear water.
Identifying the critters – The University of Wisconsin has two excellent keys for identifying the “bugs.” There is a key for both ponds and streams. To use this key, you need to look at the words, not just the pictures. For young children who cannot read, you will need to ask them questions. For example, does the critter have a shell like a snail, or no shells? Does it have legs or no legs? How many legs? These questions will eventually lead you to a picture.
What do they tell us? – Some of these “bugs” can live in nasty, polluted water and survive. Some critters will die if the water has just a small amount of pollution. Some require clean gravel or rocks for homes, while others can live in mucky areas. After you identify the critters, you can sort them into high quality, medium quality or low quality. A more detailed data sheet is available from MiCorps, Michigan’s volunteer lake and stream monitoring program.
Aquatic True Bugs
Blood Midge or Midge Larvae
Other cool stuff:
- Adult mayflies do not have a working mouth. They do all their feeding as a larva, and as adults they mate and die. They usually live less than a week.
- There are many species of leeches, but many species do not feed on human blood. Some feed on birds, turtles, fish, snails, dead plants, animals or swallow aquatic insects whole.
- Dragonfly larva can jet through the water by sucking water into their abdomen (their “butt”) and squirting it out.
- If you look closely at aquatic beetles you will notice an air bubble on their backside. They breathe through their “butts” (actually their abdomen). They use the air bubble like a scuba tank and swim around under the water. Every so often, they go back to the surface to get fresh air in their “butt bubble” and swim underwater some more.
- Although we sometimes call all creepy crawly creatures bugs, that is not correct. Bugs are a certain type of insect with overlapping wings, often making a diamond pattern. Bugs also have piercing mouthparts, like a needle, that they use to suck juices out of plants or animals. The water striders that skate on the surface of streams and ponds are true aquatic bugs. In contrast, ladybugs are not bugs, they are beetles.
- Backswimmers and water boatmen are usually light colored on the part of their body that faces down in the water. When a fish is swimming below them, looking at the light color, it blends in with the sky. Both backswimmers and water boatmen are true aquatic bugs.