The purpose of this article was to show that anuran vocal sacs are not just used for acoustic communication, but it is instead a tool that anurans use for multimodal signalling.
The authors discuss how the traditional views misinterpret the idea that vocal sacs are used only as a way for communication and breathing for anurans. In addition, the article also points out that vocal sacs most likely evolved as selection that favored calling efficiency. However, the authors do emphasize how the diversity of the visual aspects (can be seen in the image below) such as, shape, size, and color, of anuran vocal sacs suggests that the overall purpose of anuran vocal sacs aren't just for communication.
Lastly, the authors provide evidence that vocal sacs may play a role
in chemical signalling, through discussing how African reed frogs
(Hyperoliidae) all possess a prominent gular patch on their vocal sacs.
This gular patch was recently found to be a gland that produces volatile
compound mixtures and are released when the vocal sac is inflated (can be seen in image to the right). Therefore, the diversity of vocal sacs between all anurans can be better explained by going against the norm of believing vocal sacs are just used for acoustic communication, and realize instead that vocal sacs are tools for multimodal signalling.
This research is valuable because it gives us a better understanding of anurans and their evolution. We now can understand that the vocal sacs use different modalities other than acoustic signalling that range from seismic and visual to chemical. Furthermore, since little research was presented on the role of chemical signalling in anuran vocal sacs, this article can promote further research on this, thus allow us to discover even more information on the true nature of anuran vocal sacs.
Citation:
Starnberger, I., Preininger, D., & Hodl, W. (2014). The anuran vocal sac: a tool for multimodal signalling. Animal Behaviour, 97, 281-288. doi:10.1016/j.anbehav.2014.07.027
Link:
4 comments:
Wow! You've got some crazy looking vocal sacs there! I could easily buy into an argument that the double sace bellow and above are used to scare away predators! Is that willow patch over the vocal sac fat? I wonder if it is, whether that means for humans, singers with more fat on their necks are at an advantage...
What are some examples of the vocal sac being used as a visual signal?
In a more recent but similar article about the importance of chemo-signals in anuran reproduction scientists noted that male anurans will develop "breeding glands" during breeding seasons. I wonder if this development is tied to signaling for vocal sac development.
I think you are right that this opens the door for a lot of further studies into the importance of chemosignaling in anuran communication!!
The article about breeding glands can be found here:
Woodley, S. (2015). Review: Chemosignals, hormones, and amphibian reproduction. Hormones And Behavior, 68(Chemosignals and Reproduction), 3-13. doi:10.1016/j.yhbeh.2014.06.008
Fascinating article, Chelsea. Thanks for sharing this!
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