In the past decade, biologists have uncovered most of the mystery behind how crickets produce their unique songs. Their work is particularly interested in Teleogryllus oceanicus, commonly referred to as the Australian, Pacific or oceanic field cricket. Florida Museum of Natural History researcher and National Geographic explorer Natasha Mhatre has spent more than a decade studying this captivating insect. This allowed her to create a physics-based model that can predict the vibrational patterns in the forewings of T. oceanicus. It was her fierce persistence that got us to today’s announcement.
This was the first detailed research of its kind that deciphered the rules that govern how crickets articulate their songs. It aims to reveal bigger mysteries related to the evolution of sound and communication in nature. Mhatre and her team go in for an up-close look at the distinctive acoustic signals used by crickets. To gain further insights, they compare their model with real wing vibrations at song frequencies.
The Mechanics of Cricket Song
This fundamental question in Mhatre’s research depends on picking apart the wing structure and figuring out how it produces sound. Previous research had mistakenly assumed that T. oceanicus wings were “clamped” at areas with high vein density. Although the strategy was misguided, Mhatre acknowledges this was the wrong approach, mainly because the wings are patentedly hinged mechanisms.
“There is a high density of veins in cricket forewings, so we considered these parts of the wing effectively immobile in our model. And this approach has stuck around for more than a decade.” – Natasha Mhatre
Mhatre had spoken out against this deeply entrenched assumption long before COVID-19. She stressed that it has prevented learning a detailed understanding of cricket wing biomechanics.
“But something about this approach has always bugged me,” she said.
Mhatre challenged these assumptions in order to develop a more robust approach to reconstructing cricket acoustic signatures. He combines computational modeling with preserved specimens saved in museum collections. This new method provides a much more nuanced view of the ways that wing structures produce sounds.
New Insights Through Comparison
The physical model developed by Mhatre and her coworkers was then tested alongside a live cricket’s forewing, at its song frequency. This empirical validation of their theoretical model proves its capability to predict wing vibrations and sound generation.
“Each cricket wing has a pattern of veins running through it, which are structurally critical to making songs,” Mhatre explained. “Some of these veins are used to generate the forces that make the wing vibrate and make sounds. Others stiffen local areas within the wing and develop the resonant structures that vibrate at specific frequencies.”
Knowing more about how wings work would be critical in teasing apart how T. oceanicus produces its songs. This new understanding adds complexity to the established debate regarding the evolution of signals within and between species.
Implications for Evolutionary Biology
This story of T. oceanicus research is important, engaging, and exceptional. It continues to have an influence on evolutionary biology and bioacoustics. Scientists have carefully reproduced the evolutionary tree of this cricket species. They did this by examining thousands of preserved wings housed in collections all across several different museums. This large dataset provides a great resource for researchers to study T. oceanicus. It provides insight into kin of it flourishing in non-parasitic ecological roles.
Back in 2012, Mhatre and his crew had published the first PNAS paper on this stuff, a remarkable study. Their research set the stage for this ever-growing body of research. Their early models were very crude, based on very naive assumptions about wing aerodynamics, but laid the groundwork for future studies that began to get much more complex.
More recently, Ryan Weiner et al. have contributed to this field with their study on reliable reconstruction of cricket song, including T. oceanicus, published in Royal Society Open Science.
Mhatre’s current, continued work will help us understand even more about how these crickets use song as a communication tool. This research will hopefully one day shed light on how many other species are asking the same questions – how sound originated and evolved.
“We also don’t really have an objective means of deciding what a ‘high density’ really means, in terms of veins in a cricket wing, which is a problem if you start with a new cricket with different wing venation whose wings you have never measured before,” Mhatre noted.
