Eastern Illinois University The Keep Faculty Research & Creative Activity Biological Sciences 1-1-2007 Using dragonflies sa common, flexible, and charismatic subjects for teaching the scientific process Paul Switzer Eastern Illinois University, [email protected] Follow this and additional works at: https://thekeep.eiu.edu/bio_fac Part of the Behavior and Ethology Commons, Entomology Commons, and the Terrestrial and Aquatic Ecology Commons Recommended Citation Switzer, P.V. (2007). Using dragonflies as common, flexible, and charismatic subjects for teaching the scientific process. The American Biology Teacher 69(3): 158-162. This Article is brought to you for free and open access by the Biological Sciences at The Keep. It has been accepted for inclusion in Faculty Research & Creative Activity by an authorized administrator of The Keep. For more information, please contact [email protected]. as Common, Flexible & Charismatic Subjects Using forDragonflies Teaching the Scientific Process P AUL V. S WI T ZER See this article with its beautiful images in full color online at: http://www.nabt.org/sites/S1/File/pdf/069-03-0158.pdf. iology laboratories are usually designed around eat other invertebrates in the jar . Adults are a bit more wary, convenientB and available subjects . For example, for animal yet if students avoid sudden movements or approaches, laboratories Daphnia magna, Drosophila melanogaster, frogs, they can get within inches of many common species . rats, and mice are common animals that are relatively easy Capture requires no more exotic equipment than either to obtain, relatively cheap, and consequently lend them- aerial (for adults) or aquatic (for larvae) nets, and adults can selves well to laboratory experimentation . On many cam- be quickly and cheaply marked with permanent marking puses, however, a body of water exists–either in the form pens or with white correction fluid . Moreover, adults can be of a creek or small pond–and this water attracts numerous used in many projects without capture . In addition, males animals that have tremendous potential as subjects for and females of most common species can be distinguished teaching . Chief among these animals are the dragonflies from a distance . and damselflies . Dragonflies and damselflies occupy differ- Second, dragonflies are very charismatic and are effec- ent suborders of the insect order Odonata, and, although tive ambassadors of the insect/invertebrate world . Probably both make great subjects for teaching, I focus primarily on only butterflies rival dragonflies as the most popular inverte- dragonflies in this article . Below I explain why dragonflies brate in jewelry and clothing, and dragonflies provide inter- make great subjects, give some practical advice for using esting links between the natural world and art and poetry . them in your teaching, and then For example, dragonflies have provide a few specific examples long played an important role for how I have used them in my in Haiku, as a brief Internet classes . My hope is that by giving search for “Haiku” and “drag- a little background information onfly” will demonstrate . Also, INQUIRY and& INVESTIGATION a bit of an admittedly biased in my experience, once stu- push in their direction, dragon- dents acquire just a little infor- flies will become more appreci- mation about dragonflies, only ated and more utilized in science praying mantises (another fas- teaching . cinating insect predator) rival dragonflies for intrinsic “insect Dragonflies as interest .” Because of their ris- ing popularity with the general Teaching Subjects public, dragonfly field guides Dragonflies are ideal teach- have become more common ing and research subjects for a and more “user-friendly,” in number of reasons . First, they the sense that many are now are common and relatively easy designed with the layperson in to work with . Students can mind . Consequently, identify- approach them closely, watch ing the common dragonflies them, and capture, mark, and and, to a lesser extent, the release them . Dragonfly larvae damselflies, is easier than ever . are aquatic, easy to capture using Third, dragonflies have a aquatic nets, and seem content variety of interesting ecologi- to go about their business quite cal roles and behavior in both readily either in the field or in Figure 1. Rainbow bluet damselfly (Enallagma antennatum) the larval and adult stages . the lab . For instance, when held Dragonfly larvae are dominant in jars after capture, the larvae perched on a pond. (Photo by Paul V. Switzer). invertebrate predators in many behave normally and will try to aquatic habitats and can help shape communities . Larvae capture prey by shooting out a modified lower mandible Paul V. SwiTzer is Associate Professor, Department of and grabbing prey, and larvae of larger species may eat Biological Sciences, Eastern Illinois University, Charleston, small vertebrates (e .g ., amphibian larvae and fish) as well as IL 61920; e-mail: [email protected]. invertebrates . Dragonfly larvae move either by crawling or 158 THE AMERICAN BIOLOGY TEACHER, VOLUME 69, NO. 3, MARCH 2007 by jet propulsion, using water forc- in mind . Students will need good ibly expelled out their anus . Adults aerial nets and their capture suc- are also predaceous, and males of cess will be higher if they minimize many of the most common species their bodies’ projection against the are territorial, exhibiting a variety of plain sky background from the per- conspicuous aggressive and mating spective of the dragonfly . When behaviors . Their chases and fights possible, students should approach can make quite an impression, espe- and swing from behind the dragon- cially once the students figure out fly to decrease the chances of the what they are observing . dragonfly detecting them (again, this presents a possible student project!) . Once captured, the adults Practical of larger species can and will bite, Considerations but if students hold them by the thorax (under the wings) or by the wings, the dragonflies will not be Identification & able to reach their fingers . Students Seasonality should also be careful with the One of the first things you need wings; dragonfly wings do not have to know for studying dragonflies is scales that will rub off as do but- how to differentiate dragonflies and terflies and moths, but their wings damselflies; one can easily accom- are still fragile . To prevent damage, plish this by noting obvious aspects students should hold more than of their appearance . Adult dragon- one wing at a time, holding them flies have robust bodies, hold their folded over their back . wings out to their sides at rest, and Figure 2. Eastern amberwing dragonfly (Perithemis ten- Adult dragonflies can be often have eyes that meet in the cen- marked with white paper correc- ter of their heads; their larvae tend era) male in an “obelisk” posture. This posture helps them tion fluid, permanent markers, or to be somewhat “cricket-like” and regulate their body temperature during hot summer days. small amounts of acrylic paint on do not have any projections off the (Photo by Paul V. Switzer). their wings or abdomen . Before posterior portion of their abdo- marking any dragonflies, con- mens . Adult damselflies have sider the following . First, dragon- a long, thin abdomen and are flies are flying insects; this means overall more “dainty” looking . that students will want to mini- They hold their wings together mize the amount of correction over their backs at rest and have fluid or paint that they apply . eyes on the sides of their heads Second, after adults are handled that do not meet in the middle . and marked, the dragonflies will Damselfly larvae are likewise often fly away . Many of these thin and have three flat, paddle- individuals will come back with- like gills projecting off the poste- in minutes, a few hours, or by the rior of their abdomens . next day, but there is no guaran- Dragonflies, like most tee . Therefore, if you are doing a insects, will be affected by weath- project that requires individual er conditions, time of day, and identification, capture and mark season . This fact provides some as many as you can well ahead of limitations as well as possible Figure 3. Widow skimmer dragonfly (Libellula luctuosa). The when you intend to collect data . questions for student projects . white color on the wings and bluish color on the abdomen only For many of the territorial spe- cies, however, the males tend to In general, adults are active on appears as the male matures. (Photo by Paul V. Switzer). sunny days as long as it is warm remain in the same location, even enough (above 75˚ F or so) and returning to the same perch after are more active in the middle of the day than morning and flying away . Students can take evening . On overcast days, dragonflies require higher ambient advantage of this behavior to avoid pseudoreplication during temperatures to exhibit typical levels of activity . Furthermore, as relatively brief studies . with many insects, dragonflies (adults and nymphs) are more The territorial behavior of adult male dragonflies provides common in summer and fall than in spring . many possibilities for student research . Perching adults will often use perches you provide; consequently, students can study Handling, Marking & Observing Adults & experimentally the perch characteristics that dragonflies prefer (e .g ., Switzer & Walters, 1999) . If you do provide perches, how- Larvae ever, allow the dragonflies a day or so to become accustomed to Many satisfactory studies can be done without ever han- the change in their habitat . Many dragonflies also pursue spe- dling a dragonfly . However, if your study requires that you cies other than their own, which can make for some interesting capture adult dragonflies, you should keep a few considerations and easy observational studies (e .g ., Schultz & Switzer, 2001) . DRAGONFLIES 159 Some species have relatively clear ter- dragonflies among your students and ritorial boundaries; you can figure out to help identify the species on your where these boundaries are by observ- campus .