What noisy creature consumes only liquids, lives by safety in numbers, and can enhance CO2 production in streams?
The periodical cicada!
The Periodical Cicadas’ 15 Minutes of Fame
You may have noticed that the news cycle has recently been dominated by stories about cicadas as some regions in North America excitedly await the arrival of the Brood X cicadas after 17 years. Over the past couple of weeks, I eagerly scoured as many online articles as I could to learn more about this incredible natural phenomenon.
Despite the excitement that the online world seemed to share about the periodical cicadas, I couldn’t help noticing that a similar storyline was being circulated. It goes something like this: periodical cicadas remain underground for 13-17 years before emerging for a single season to mate and reproduce. They simultaneously create a cacophony or chorus (depending on the listener’s opinion) of mating calls that can range from 80 to over 100 decibels in volume. For comparison, this is similar to the volume range of a food blender, a chainsaw, or a motorcycle!
I felt like something was missing; as if the cicadas deserved a highlight that better encompassed the lives of these tiny yet somewhat mysterious living beings. I was entranced by these creatures and intrigued to know more. Do you feel the same way? Let’s embark upon this journey together to learn more about the incredible periodical cicada!
Before we begin, let’s quickly review the basics of the periodical cicada life cycle:Here!
Insect and… secret keeper?
One of the most puzzling mysteries surrounding the periodical cicada is why they wait to emerge from their underground sojourn for 13-17 years. Why are these numbers so steadfast and significant for the periodical cicada?
While there isn’t a concrete explanation for why periodical cicadas emerge after 13-17 years, several theories give us insight into this phenomenon. For example, one theory is that cicadas have an internal clock programmed for that amount of time, and another theory is that cicadas measure time through changes in the composition of sap and other fluids they consume from tree roots and other organic matter underground.
Change Agents That Can Outsmart Predators
A wide variety of animal species are predators to the cicadas. As a result, the periodical cicadas purposefully emerge as a group over just a few weeks, inundating their location and overwhelming potential predators. This strategy is called predator satiation, and it enables each brood to maintain enough living members to mate and reproduce without being over-consumed by another species. In other words, a lone cicada is easy prey, but there is safety in numbers!
Not only do periodical cicadas make quite the appearance on land, but they have also been found to make quite a stir in stream ecosystems as well! A 2008 research study found that community respiration (the production of CO2 in an ecosystem) increased with the arrival of periodical cicadas. The findings also state that cicada detritus is a much-needed component in the stream ecosystem that fuels other species, such as microbes and invertebrates, with nutrients. Periodical cicadas certainly make a big splash in stream ecosystems!
Effects of Human Activities
Once their waiting period is over, periodical cicadas rely on a specific ground temperature to signal when it is time to emerge from their seclusion underground. However, climate change and human activity, such as pesticide use and building development, could be affecting this process. As global warming continues along the current trajectory, ground temperatures are warming earlier and earlier in the spring season, potentially setting the emergence dates for periodical cicadas off-kilter, even by several years.
Luckily, entomologists are on the case, studying global warming trends and beginning to research how this could (and may already be) impacting cicadas. And, with the help of supporters like you, organizations like Bio4Climate are working with communities to further ecological restoration efforts and advocate for policies that will benefit species like the cicada long-term.