The rock band America wrote in their 1971 hit song, A Horse with No Name, 'The ocean is a desert with its life underground, And a perfect disguise above.' The song tries to describe what we don't see as we gaze over the gently, rolling waters. Unless you literally submerge yourself under the surface of one of our local streams, lakes or rivers, you would never know how much life exists in these, freshwater ecosystems. Many critters, including fish, insects, mussels, crayfish and snails spend their entire lives in the water, hidden from our everyday views. But just because they're underwater, doesn't mean they're not important, fragile or downright cool! Some of my favorite animals are always wet!
Scientists have also taught us that an aquatic habitat that hosts a diversity of species is an indicator of good water quality, and since many humans get their drinking water from these same sources, that's good news for us too. Clean water for our aquatic animal friends = safe, healthy water for humans! So, what lurks under the surface of our local waterways? That depends where you look…..and sometimes they look for you, like the 'alleged Lamprey eel incident of 1980.'
As the legend goes, my sister Cathy was fiercely pursued one summer afternoon by a crazy Lamprey eel. It was during one of her famous tube-floating trips down the Delaware River, when the snake-like fish with a vacuum cleaner mouth and rows of razor-sharp teeth tried to latch on to her leg. This event continued for over a mile. It was reported that only my sister's strong hand-paddling skills and MacGyver-like strategy of bumping and spinning off every shallow rock, saved her from the jaws of this slimy creature from the deep!
If we break our aquatic habitats into two categories, they would be moving waters, and still waters. Moving waters include streams and rivers, and non-moving waters would be ponds and lakes. Critters living in moving water have adapted to living in constant flow and currents, including specially designed body parts to 'hold on' to surrounding rocks or submerged trees. Animals living in ponds or lakes may face different challenges, like increased water temperatures and lack of dissolved oxygen levels. Either way, life under the surface is harsh and risky at best, and short-lived at worst.
When most people think of animals that live in the water, they think of fish, but the largest group of freshwater animals are the macro-invertebrates. These organisms are large (macro) enough to see with the naked eye, such as insects, clams, crayfish and snails, and do not have a backbone (invertebrate). They may inhabit moving or still waters. Since they really can't escape pollution, scientists use macro-invertebrates as a type of 'measuring stick' for water quality. Individual species like stoneflies, mayflies and freshwater mussels are of particular interest to biologists studying rivers and streams. Even the smaller relative of the lobster, the crayfish, is an important part of the freshwater food chain. Known as a crawdad in other parts of the country, the crayfish may live its entire life under one rock, leaving only to find food or defend its territory. The crayfish and insects may have an advantage in numbers, but they have to, if they want to survive the many predators that also share their water world with them.
The biggest, natural threat to the smaller critters in an aquatic habitat, are fish. There are many species of fish that live in our local waterways, and most of them enjoy a good meal of crayfish, dragonflies or stoneflies. If we were to grab a mask and snorkel and take a close look at some of our local bodies of water, you would be surprised at what you might spot swimming under the surface. Our streams would most likely have many species of 'baitfish,' such as minnows, shiners and dace. These same moving waters may also host larger species like Brown trout, Smallmouth bass and White suckers. The larger flowing water areas, like the Schuylkill River would harbor Rock bass, Smallmouth bass, Walleye, Channel catfish and Carp. A trip to the local pond or lake would reveal Bluegill, Perch, Crappie, Largemouth bass, or even the toothy Pickerel.
We all need clean water to survive-humans, and non-humans. It's the most precious natural resource on our planet. So, the next time you visit a local lake or pond, or drive across the Schuylkill River, take a minute to remember the diverse, but fragile, aquatic animals that live under the surface!