Science ideas for young children: 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 if the water is clean or polluted.

Playing in the water
Photo by Darren Bagley, MSU Extension.

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. This article is part of 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. 

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. If you are in a river or stream, place your net so the water is flowing into it. Kick up the bottom with your feet, and the critters will come loose and get caught in your net. 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.

Exploring science in the water
Photo by Darren Bagley, MSU Extension

Have two white trays for sorting the critters. White trays allow you to see the critters better. Dish pans work great for this, but you can also use leftover restaurant takeout trays. Put a little water in both trays. After you catch the critters in your net, dump them the tray, 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 excellent keys for ponds, streams and wetlands to help in identifying the bugs. To use these keys, 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 by their water quality requirements: high quality, medium quality or low quality. A more detailed data sheet is available from MiCorps, Michigan’s volunteer lake and stream monitoring program.

High Quality

Medium Quality

Low Quality

  • Mayfly
  • Caddisfly
  • Stonefly
  • Gilled Snails


  • Dragonfly
  • Damselfly
  • Aquatic Beetles
  • Scuds
  • Aquatic True Bugs
  • Air-Breathing Snails
  • Mosquito Larvae
  • Blood Midge or Midge Larvae
  • Leeches

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 only a day or two.
  • 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. Penguins, frogs and turtles are often similarly colored for a similar reason. Both backswimmers and water boatmen are true aquatic bugs.

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