Author’s Name(s): Paul, Laurence & Mendyk, Robert
Name of Journal: Herpetological Review
My article investigated tail fluorescence in pit vipers and how it could be used to attract prey. Bioluminescence has been observed in many species of amphibians and reptiles, but has not been well researched (Laurence & Mendyk, 2021). This research was inspired by a group of captive Hagen’s pit vipers that exhibited tail fluorescence. This brought up the question of whether all Crotalinae have this trait or if it had something to do with these individuals being in captivity (Laurence & Mendyk, 2021). Laurence and Mendyk (2021) used fluorescent photography to capture tail fluorescence in ten genera of pit vipers. They used both wild and captive individuals to investigate if this trait was correlated with captivity. One thing I found interesting was that some of the individuals they photographed were roadkill victims. This is because many of the species they were working with are venomous so using roadkill samples allows them to avoid the dangers of handling these species. They observed tail fluorescence in 88.6% of the Crotalinae specimen. They also found that how much of the tail was fluorescent and what color it was varied based on the specimen’s age and species. Since this fluorescence was observed in both wild and captive individuals, they concluded that is a common trait in Crotalinae and it was not derived from captivity. They also found that when they observed captive individuals over time, the amount of tail fluorescence that was observed decreased and it was different between females and males. They found that species who had conspicuous tail coloration in juveniles more commonly had tail fluorescence. An example of conspicuous tail coloration in juveniles would be the Agkistrodon piscivorus and Agkistrodon contortrix. In lab we saw two juvenile specimens in jars, they both had the lighter tail tip. I included Figure 1. From the text where you can see the lighter tail of a young Cottonmouth with tail fluorescence in panel C.
The research by Laurence and Mendyk (2021) adds to our understanding of how pitvipers use their tails. Since fluorescence is limited to their tail rather than based on their body patterning, it is clear it has some specific function (Laurence & Mendyk, 2021). The researchers concluded that this function is prey capture. In many crotalinae species, the conspicuous tail color in juveniles allows them to use caudal luring (Laurence & Mendyk, 2021). This means that they can wiggle their tail around to mimic a worm, tricking their prey into approaching (Laurence & Mendyk, 2021). Therefore, fluorescence would help draw the attention of prey to their tail. As they get older, their diet shifts and they no longer eat prey that would fall for this mechanism, explaining why tail fluorescence is not as strong in adults (Laurence & Mendyk, 2021). They also discovered that grass that is in the diet of rattlesnakes’ prey, has similar structure/fluorescence to the rattlesnakes’ rattle. Meaning, rattlesnakes can use their fluorescent rattle to blend into their background to avoid startling their prey as they approach. Both of these methods are ways that Crotaline species can use this tail fluorescence to help capture prey. This allows us to have a better understanding of how these species hunt and use their tail.
This research is not only valuable because it provides us with more information about how bioluminescence is used in reptiles, but it also helps us better understand the evolution of the rattle and where bioluminescence originated. Since tail fluorescence appears to be important to caudal luring, we can use this information to infer that species who have not been included in bioluminescent research but use this mechanism, likely have tail fluorescence. This allows us to see which groups do/do not have this trait so we can pinpoint where it appears on the phylogenetic tree. Since rattlesnakes are a “newer” branch in Crotalinae, the fluorescent rattle may have first evolved to be used to blend in with the environment to make capturing prey easier and not as a defense mechanism (shaking it to make a warning sound) (Laurence & Mendyk, 2021).
3 comments:
Very interesting! Did they mention whether the visual system of the prey is likely to be sensitive to the fluoresced wavelenghts?
They did note that the prey of rattlesnakes definitely are. They discussed how the majority of their prey are rodents that eat flowers and grains and have retinal receptors that are sensitive enough to function in low-light.So these rodents are likely able to use biofluorescence to help them locate their food. They also noted that this would explain why rattlesnakes usually ambush their prey. They are able to remain at rest with their rattle pulled in close to their head/mouth and wait for the prey to mistake their rattle as grass and ambush them once they are close enough.
They also noted that some lizards and frogs are. These organisms have sensitivity that allows them to see in low-light, which suggests that they are sensitive to fluorescence. It was also noted that some of these lizard/frog species use fluorescence to communicate within their own species, so they must be able to detect it.
This was such an interesting article! I had no idea that some snakes use bioluminescence. It sort of reminds me of angler fish since they also try to lure their prey with bioluminescence. After reading this, it makes me want to research if any other reptiles implement bioluminescence as a prey luring strategy. Great job on the post!
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