An adult dragonfly at Nature Boardwalk.
Today a few colleagues and I put on our boots and waded into the shallows of the pond at Nature Boardwalk to take samples of the invertebrates that are colonizing the habitat. We swished our finely meshed nets back and forth in the water to collect aquatic invertebrates and then quickly transferred everything we’d caught into a bucket for temporary holding. Once we’d caught a few bucketfuls of tiny critters, we took our equipment and our specimens indoors for sorting and identifying.
Lincoln Park Zoo scientists sort through and identify aquatic pond invertebrates.
While adult dragonflies are easy to see swooping over the pond’s surface, you have to look very closely to see all of the other life stages of these fascinating insects. In the nymph stage, one can begin to see the resemblance between adults and juveniles, as the nymphs have very large eyes and begin to take on the elongated abdomen of adult dragonflies.
The early larval stages, however, look nothing like the adults to the untrained eye. They look more like small black-and-white striped grubs. Only upon close inspection (and perhaps with the aid of a microscope) can one see that these larvae do resemble the nymphs, if you look close enough.
The dragonfly larva and nymphs have been placed in a petri dish for closer inspection. Here you can see nymphs of various sizes, as well as a small larva (the very small, striped organism).
We also saw many exuvia, or molted dragonfly exoskeletons, showing the evidence left behind as the dragonfly progresses form one life stage to the next. After we were done sorting and identifying, we put all of the creatures back in the pond where we found them. We’ll continue to sample invertebrates and monitor development of this population over time. This is just the beginning of this research for us Nature Boardwalk biologists.
On the underside of this fencing you can see the exuvia, or shed exoskeleton, of a dragonfly that has molted and left its old outer casing behind.