Micro-CT for Insect Inspection: Cicada ~ Analysis of Its Anatomy
The Quintessential Sound of Cicadas
Heard from the front porch, garden swing, or evening walk, the song of the cicada is the sound of summer. The sounds are from male cicadas, and are part of their mating ritual to attract females. Several species of cicada may gather when calling, creating an extraordinarily loud chorus, especially considering their small size. They are so loud, engineers are studying cicadas in an effort to develop new techniques for amplifying sound.
Biomimicry, or imitating life from nature’s designs, goes back to the 15th century when Leonardo da Vinci studied birds to create his drawings for flying machines. The unique anatomy of the cicada provides another source for scientific inspiration today.
|Side Note: Locusts are actually a type of grasshopper known for its presence in Egypt and Palestine. It is important to note that locusts and cicadas are not related. Cicadas are a part of their own family, called Cicadidae, and are broader-bodied than a grasshopper. Another distinction between the two is that locusts have large mandibles for devouring crops, whereas cicadas eat sparingly and mainly feed on sap from trees.|
17 Years in the Making
The story of the cicada begins with nymphs burrowed in the earth, waiting for their time to emerge. Every 13 or 17 years, depending on the species, an unknown trigger causes the cicada nymphs to rise from the ground. This can happen practically overnight, sometimes causing confusion with a plague of “locusts” (See side note).
Once the cicadas emerge, they scale nearby trees or any upright object until they reach their stopping location. Their bodies then undergo dramatic changes by shedding their nymphal exoskeletons to reveal their mature cicada form with wings and reddish-orange eyes. They are known to be clumsy fliers, yet perch high in the trees where they fill the air with their increasing tempo of humming and clicking.1 The males use this unique sound to attract females for mating.
Figure 1. Preserved female cicada found near our Micro Photonics’ Pennsylvania office.
Why Create a Micro-CT of a Cicada?
Billions of cicadas have invaded Pennsylvania this year so we found it fitting to highlight this interesting insect. One of the most prominent features of the male cicada is its unique sound, which is attributed to the snapping of ribbed membranes on the abdomen, called the tymbal. During the sound-making process, the ribbed membranes are contracted and released at a high frequency (300-400 times per second). The snapping back of these membranes is what produces the sound, which is amplified by an air chamber in the cicada’s abdomen.2 Below are images showing the anatomy responsible for the male cicada’s sound.3
Figure 2. Anatomy of the male cicada, showing the ribbed membranes responsible for its sound.2
Our specimen is a female and does not have tymbal membrane (see Figure 3). The females create sound by making wing-flicking signals and/or clicks through rapid wing movements that correspond with the male’s song. Our micro-CT image reveals the intricate body structure of the female cicada and demonstrates the possibility of future non-destructive studies to investigate other aspects of the anatomy of these fascinating insects
(see Figure 4).
Figure 3. Micro-CT scan of a female cicada showing the lack of the tymbal membrane (area of representation in red oval).
Figure 4. Internal anatomy through a cutaway view of the cicada.
We hope you enjoyed learning about the cicada. If you have a unique sample that you would like us to scan for you, please let us know. We would be glad to highlight your image as an Image of the Month. Please feel free to e-mail firstname.lastname@example.org or call 610-366-7103 if you would like to submit a sample or learn more about our laboratory testing.
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Micro Photonics Imaging Laboratory, Allentown, PA
- Gregory A. hoover, Periodical Cicada. Penn State College of Agricultural Sciences, http://ento.psu.edu/extension/factsheets/periodical-cicada. (Accessed August 22, 2016).
- Encyclopaedia Britannica 1911 [Public domain], via Wikimedia Commons. https://upload.wikimedia.org/wikipedia/commons/9/9b/EB1911_cicada_tymbal_structure.png. (Accessed August 23, 2016).
- Acoustical Society of America (ASA). “Secrets of the cicada’s sound.” ScienceDaily. https://www.sciencedaily.com/releases/2013/05/130530152846.htm. (Accessed August 22, 2016).