By Michael Caduto
Ponds are places of endless discoveries. They are liquid eyes gazing up to the sky and catching the sun’s life-giving energy. Who wouldn’t want to spend a hot summer day at the pond?
Turn your next pond trip into an adventure. Bring a shallow white tray with sides high enough to hold water, a pair of tweezers, a large tea strainer, a hand lens and some old sneakers for mucking around. Take along a copy of an easy-to-use field guide such as Pond Life by George K. Reid (A Golden Guide from St. Martin’s Press, 2001, $6.95.)
Find a shallow pond with a safe, gradual slope along the shore. (Water wings are always a good idea for young children.) Fill the tray with water and place it in the shade at the water’s edge. As you wade in the shallows, sift the tea strainer through the plants and mud and you’ll catch globs of muck crawling with insects, worms and other aquatic life. Use the tweezers to gently lift each critter out of the tea strainer, taking a close look through the hand lens before placing it into the tray of water.
While you’re mucking about, be careful not to slip on algae. Although algae are very small, as sun-catchers they are the major source of energy that feeds the animals in a pond’s food chain. Algae are as important to the pond as a field of grass is to a herd of grazing cows.
The pond is full of microscopic crustaceans that eat free-floating algae, but the side-swimmer, or scud, is large enough to see. It looks like a tiny shrimp doing the sidestroke as it searches for dead plants and animals to eat. Its larger relative, the crayfish, is also a scavenger.
Mosquito larvae rest on the surface with breathing tubes exposed to the air like snorkels. Phantom midge larvae have flotation devices that look like tiny water wings. These and other larvae are eaten by fish, water treaders, whirligig beetles, red-spotted newts and the fish spider. Water striders use the water’s surface much as spiders use a web to catch prey.
Whirligig beetles are the shiny, bluish-black insects that gyrate around on top of the pond. They have two-parted eyes that are divided horizontally so that they can focus in the air and underwater at the same time. When diving they use an air bubble as a tiny aqualung.
If you catch an oblong insect that is covered in dark green algae, it is probably a predaceous dragonfly nymph. (Be careful, they bite). Tap the end of the nymph with tweezers and it will shoot forward with jet propulsion by forcing water out of its abdomen. These nymphs will eventually crawl up at the edge of the pond, shed their skins and spread dragonfly wings. Watch for adult dragonflies patrolling the air over the pond in search of prey. These aerial acrobats can hover in place or fly up to 35 miles per hour—about the speed of a racehorse!
When it comes to predators, dragonfly nymphs more than meet their match in giant water bugs. These flattish, oval insects ambush tadpoles, other insects, crustaceans and even small frogs, then they inject enzymes into their prey and suck up the innards. They can grow to be three inches long and pack a nasty bite that has earned them the nickname of “toe biter.” The female giant water bug, Belostoma, lays and cements 100 or more eggs onto the male’s back. He dutifully carries the eggs for about a week until they hatch, and then protects the young nymphs from predators.
Moving up the food chain, these smaller predators are eaten by larger hunters like bluegill sunfish, catfish or large-mouthed bass. Common water snakes, otters, minks and great blue herons are among the pond’s top predators. Swallows skim over the pond in search of insect meals, and I once watched a Belted Kingfisher swoop down to catch a dozen small fish during the course of an hour. Little brown bats eat more than their own weight in mosquitoes and other insects each night.
When your pond adventure is over, gently release everything you’ve caught back into the shallow water. Taking care of life in the pond means there will be no end to the mysteries for the next visitor.
Turtles bask to absorb heat from the sun. Basking helps them control body temperature and maintain their metabolism. If they become too hot, they slip back into the cool water. This turtle is covered in duckweed—a group that contains the world’s smallest flowering plants. Photo: Michael J. Caduto
*This article is part of an occasional series to guide children and families when exploring the world around them.