Cicadas are famous for appearing in large numbers. These groups make such loud sounds that fiber optic cables can detect the noise. However, this year, there is also attention on how they urinate. Instead of releasing urine in small drops that they flick from their behinds like other insects and tiny creatures, cicadas urinate in high speed streams more similar to large mammals. This unique urination behavior is explained in a research paper published on March 11 in the journal Proceedings of the National Academy of Sciences (PNAS).
Even though the insects are small, cicadas are not always easily seen among the trees. While on a research trip in Peru, a group of scientists were fortunate to observe multiple cicadas urinating in the trees. From this encounter, the team managed to disprove two main beliefs about insect urination. loud bunchDrops vs. streams
The insects that normally
consume xylem sap from trees and urinate in droplets because it requires less energy to excrete the sap. However, cicadas consume so much sap that individually flicking away each drop would be too demanding. Using this much energy to toss away urine droplets would mean that they needed to eat even more tree sap. “Urinating in streams enables cicadas to produce a large volume of liquid waste,” study co-author and bioengineer/biophysicist
Elio Challita . “This is crucial because these insects must consume a significant amount of xylem sap on a daily basis. So they need to excrete large volumes as well.” Challita conducted his work on this study while working with tells PopSciGeorgia Tech’s Bhamla Lab and is currently a postdoctoral research fellow at Harvard University. Observe these small bugs propel urine with their behinds
[Related: Saving energy.]
Smaller animals are also expected to urinate this way since their opening is considered too small to release anything thicker than a droplet. Cicadas are
relatively large for insects and can have a wingspan similar to that of some hummingbirds . For the cicadas, it seems that urinating in streams requires less energy than flicking away the urine droplets. Scientists previously thought that if a small animal like an insect wants to expel streams of liquid, it is difficult for them since it would require energy to force the fluid out at a high speed and their bodies are not big enough. Larger animals can use gravity and inertia to help them urinate while conserving energy. The team believes that the energy savings and the cicada’s larger size enable them to urinate more like a big animal.“The biggest surprise was discovering that cicadas can urinate in streams, despite being small insects with energetic constraints due to their nutrient-deficient diet,” says Challita. “This goes against the conventional wisdom that small animals, especially those under one kilogram [2.2. pounds], cannot urinate in streams.”
‘Anticipate a lot of urination’
Studying how the cicadas urinate provides new insights into fluid dynamics in everything from
insects up to large mammals including elephants . According to Challita and the team, studying all of the different ways that animals excrete liquid has potential applications in other areas includingsoft robotics, 3D printing, and medication delivery systems Since cicadas are now the tiniest known creatures to produce high-speed jets, they could provide guidance on how to create jets in small robots or nozzles.Starting in April
two broods of cicadas–one in the Midwestern United States and one in the South–will appear at the same time. There is a small overlap region in Illinois and these broods only emerge at the same time once every 221 years. Prior to the “dual emergence” it’s not currently known what kind of impact their urination will have on the ecosystem. But it could be significant. “Cicadas will be emerging in the billions this year, so expect a lot of peeing! More importantly, we don’t understand the ecological implications for the surrounding flora and fauna,” says Challita.”
Scientists finally find the enzyme that makes urine yellow
[Related: The research also emphasizes why it’s important to study some of the more ordinary and everyday aspects of animal biology..]
“By exploring these processes, we can discover interesting adaptations and gain insights into how animals interact with their environment,” says Challita. “It’s also a reminder that there’s still so much to uncover about the natural world, even in the most unexpected places, like cicada urine!”
Other insects flick urine away in droplets, but that can waste energy for hungry cicadas.
