Field Guide

Most people are repulsed by leeches. But once you get past the fact that many species are parasitic bloodsuckers, you will discover that they are fascinating creatures with an important role in nature.

You may have heard about stinging jellyfish in the ocean, but did you know that there are similar creatures living in the freshwater of Missouri? Fortunately, they’re harmless!

Bryozoans are tiny, filter-feeding invertebrates. They create colonies that can be mossy, branching, or round and jellylike.

Sometimes called “water bees” or “water wasps,” backswimmers are predaceous and can deliver a painful bite if mishandled. True to their name, they swim belly-up, and their backs are keeled like a boat, which makes back-swimming easier.

Groups of whirligig beetles swim on the water surface in quick, random patterns, searching for food. They have two pairs of eyes — one pair above water, one pair below — to help them quickly and accurately capture their prey.

Like many aquatic insects, these large oval beetles prey voraciously on other aquatic organisms. Excellent swimmers, they fly well, too, and are often attracted to lights.

Water scavenger beetles are a mostly aquatic family. They are similar to predaceous diving beetles, but unlike them many have a distinctive spine running down the center of their bellies.

Giant water bugs are huge aquatic insects that frequently fly around electric lights at night. They are infamous for the painful bite they can deliver, but fish, birds — and some people — find them tasty!

Water boatmen are one of the few aquatic true bugs that are not predatory and do not bite people. Instead, they suck juices from algae and detritus. Only a few types eat other small aquatic creatures.