Chris Anderson
Dr. House of Chameleons
Hi Everyone,
So as many of you know, my dissertation research focuses on chameleon feeding. Specifically, I'm studying how temperature effects ballistic tongue projection in chameleons. I do this in order to understand the thermal effects on highly dynamic, elastic recoil powered movements. As part of the final chapter of my dissertation, I will be going to South Africa early next year to study Bradypodion in the wild in collaboration with Krystal Tolley to answer some additional questions about this. In order to do so, however, I am still in need of some additional funding as this project is currently only partially funded.
As a chameleon enthusiast, I often wish more research was done on chameleons but like many other worthy topics, funding for such studies is often difficult to come by. Typically, however, individuals are not able to decide for themselves what projects they themselves are interested in seeing funded. As a result, I wanted to tell you all more about my research.
As reptile keepers, we all know that reptiles become sluggish when they get cold. This is because muscles contract slower as their temperature declines. My research has shown, however (PDF), that chameleons are able to project their tongues with explosive performance even at low temperatures while their tongue retraction is strongly effected by temperature. Here's a high speed video slowed down 100x showing a feeding at 35ºC (top) and 15ºC (bottom) illustrating this pattern:
The way a chameleon's tongue is projected is similar in ways to a bow-and-arrow. Muscle in the tongue contracts and stretches elastic elements inside the tongue (collagen fibers). The recoil of these elastic elements to their resting angle/length is what powers the projection of the tongue, just as the recoil of a bow that was stretched/deformed when it was drawn back by muscle contraction is what powers the launch of an arrow. Tongue retraction, on the other hand, is powered by direct muscle-power alone.
Just as a bow recoils at almost the same rate even when cold, the recoil of elastic elements in the chameleon tongue does so at a high rate of performance at low temperature as well. Because tongue retraction is powered by direct muscle contraction alone, however, it is effected by temperature just as we would expect based on how temperature effects muscle contractile rates.
Because different species frequently inhabit very different environments, it makes sense for species to optimize their performance to the conditions of their environment. As a result, the muscles of many species are optimized to perform maximally at the temperature they live at. I believe, however, that because tongue projection is only weakly temperature sensitive, that tongue projection performance will not be optimized while tongue retraction performance will be in chameleon species from different environments.
As a result of this theory, I want to travel to South Africa to look at a number of Bradypodion species that live along an environmental temperature gradient so that I can test this theory and improve our understanding of how environmental conditions effect not only chameleons, but other animals that incorporate these different types of movements.
Over the years, a number of people have asked if there was any chameleon related research they could contribute to or help support. Because this project is only partially funded, I thought I would provide a link for people interested in doing just that. So, if you'd like to help support chameleon related research, please visit the fundraising page linked below and consider helping me raise money for this study! There is an additional movie explaining the project on the page, as well as additional information on what funds are needed for. Additionally, as you can see, there are a series of awards for anyone who donates and those rewards vary based on the amount of your contribution: http://www.rockethub.com/projects/4664-thermal-constraints-on-chameleon-feeding
Thanks and if anyone has any questions about my research, I'd be happy to talk more about it and try to answer them!
Chris
So as many of you know, my dissertation research focuses on chameleon feeding. Specifically, I'm studying how temperature effects ballistic tongue projection in chameleons. I do this in order to understand the thermal effects on highly dynamic, elastic recoil powered movements. As part of the final chapter of my dissertation, I will be going to South Africa early next year to study Bradypodion in the wild in collaboration with Krystal Tolley to answer some additional questions about this. In order to do so, however, I am still in need of some additional funding as this project is currently only partially funded.
As a chameleon enthusiast, I often wish more research was done on chameleons but like many other worthy topics, funding for such studies is often difficult to come by. Typically, however, individuals are not able to decide for themselves what projects they themselves are interested in seeing funded. As a result, I wanted to tell you all more about my research.
As reptile keepers, we all know that reptiles become sluggish when they get cold. This is because muscles contract slower as their temperature declines. My research has shown, however (PDF), that chameleons are able to project their tongues with explosive performance even at low temperatures while their tongue retraction is strongly effected by temperature. Here's a high speed video slowed down 100x showing a feeding at 35ºC (top) and 15ºC (bottom) illustrating this pattern:
The way a chameleon's tongue is projected is similar in ways to a bow-and-arrow. Muscle in the tongue contracts and stretches elastic elements inside the tongue (collagen fibers). The recoil of these elastic elements to their resting angle/length is what powers the projection of the tongue, just as the recoil of a bow that was stretched/deformed when it was drawn back by muscle contraction is what powers the launch of an arrow. Tongue retraction, on the other hand, is powered by direct muscle-power alone.
Just as a bow recoils at almost the same rate even when cold, the recoil of elastic elements in the chameleon tongue does so at a high rate of performance at low temperature as well. Because tongue retraction is powered by direct muscle contraction alone, however, it is effected by temperature just as we would expect based on how temperature effects muscle contractile rates.
Because different species frequently inhabit very different environments, it makes sense for species to optimize their performance to the conditions of their environment. As a result, the muscles of many species are optimized to perform maximally at the temperature they live at. I believe, however, that because tongue projection is only weakly temperature sensitive, that tongue projection performance will not be optimized while tongue retraction performance will be in chameleon species from different environments.
As a result of this theory, I want to travel to South Africa to look at a number of Bradypodion species that live along an environmental temperature gradient so that I can test this theory and improve our understanding of how environmental conditions effect not only chameleons, but other animals that incorporate these different types of movements.
Over the years, a number of people have asked if there was any chameleon related research they could contribute to or help support. Because this project is only partially funded, I thought I would provide a link for people interested in doing just that. So, if you'd like to help support chameleon related research, please visit the fundraising page linked below and consider helping me raise money for this study! There is an additional movie explaining the project on the page, as well as additional information on what funds are needed for. Additionally, as you can see, there are a series of awards for anyone who donates and those rewards vary based on the amount of your contribution: http://www.rockethub.com/projects/4664-thermal-constraints-on-chameleon-feeding
Thanks and if anyone has any questions about my research, I'd be happy to talk more about it and try to answer them!
Chris
