Tuesday, 12 April 2011

Request: Collect the Exuviae!

Carol and Murray Seymour, KFN members, are enthusiastic observers of nature, and often direct their attention towards dragonflies and butterflies.  Carol sends this request:

"Having spent the last few years becoming familiar with the many and varied species of dragonflies we have in the Kingston area, I am now seeking to expand my knowledge of Odonata. This amazing insect actually spends only a short time as an adult dragonfly. The larger part of its life is spent as a nymph or larva in pond, lake, stream or wetland. When the nymph emerges from its egg it is barely discernible by the naked eye.  As it grows it sheds its cuticle or skin, as do all arthropods. This can happen up to fifteen times, depending on the species of dragonfly and how fast it matures. As the nymph nears adulthood, it crawls from its watery home onto a plant stem, tree trunk or rock and goes through the complex process of emerging into its new form as a dragonfly. This is the point at which the old skin, which remains attached to the plant stem, tree trunk or rock, is now called an exuviae. The exuviae of each species, like its adult counterpart, has unique physical features, but unlike the mature dragonfly the differences between species are more subtle and at the same time, more difficult to interpret. Learning to identify the species of exuviae will be a challenge, one I look forward to.

Collecting and identifying exuviae enables the student of odonatology to recognise which species live or breed in a particular habitat without having to see the more elusive adult dragonfly. It also aids in discovering new species for the Kingston area. I need help, so I'm asking you to  assist me in this endeavor. If you observe some exuviae while on your walks, please place them carefully (they are very delicate and break easily) into a small container. It would help immensely if you would label the specimen, describing location (name of lake, road etc.) exuviae platform (plant, tree, rock, boathouse etc.) and date found. If you are lucky enough to observe the nymph emerging into its adult dragonfly form and recognise the species, please add that to the label. (If you are lucky enough to have a camera with you, a picture is worth a thousand words). Please bring your find to the next meeting you attend at the end of summer.

As you can see from the photos attached, there are two basic forms. The small narrow damselfly exuviae with three feathered gills on the end of its abdomen and the rounder and usually larger dragonfly, lacking exterior gills. Thanks for your help and happy hunting."

Fragile Forktail Damselfly                                                                   Dragonfly exuviae

Photos:  Murray Seymour

No comments:

Post a Comment