Not all flashy snakes thrash dance the same!

Coral snakes are fairly well known for their bright colors. These colors serve as a warning label for their toxic venom! However, their flashy colors are not the only warning signals these snakes use to stay out of the bellies of potential predators. Coral snakes also use sounds (cloacal popping, aka defensive farting!), odors (musk), and what I’m going to refer to as the ‘thrash dance’ or quick jerky motions to deter predators! In their recent article, Dr. Moore and colleges explore the theory of mimicry in these well-choreographed anti-predator displays.

Clip 1. Coral snake thrash dance. From Moore et al., 2020 (https://deepblue.lib.umich.edu/data/concern/data_sets/tt44pm912)

Let’s take a step back, what is the theory of mimicry?

The theory of mimicry proposes that when two or more species have similar defense mechanisms (venom in the case of the coral snake) and live in the same habitat, they should start to look and act even more alike. This signal boosting will make it easier for predators to learn to stay away from these dangerous prey.

For coral snakes this means that snakes that live near one another should have more similar warning color patterns and more similar thrash dances. This way predators will encounter the same signal more often and be less likely to mess with these danger noodles. Basically, this is a safety in numbers principal!

Meme 1. Danger Noodle. Modified from Moore et al., 2020.

Do coral snake thrash dances follow the theory of mimicry?

To explore this theory, Dr. Moore and their team went to Peru and collected thrash dance videos from 25 wild coral snakes from 5 different species and 4 different locations. The snakes were exposed to different stimuli representing 1) a bird flying overhead (looming stimulus), 2) a large mammal walking nearby (vibration stimulus), and 3) a predator attack (contact stimulus). From these videos, the team analyzed the variation in color patterns and thrash dances within and among species, sizes, and locations.

Figure 1 from Moore et al., 2020. (A) An illustration of a coral snake thrashing display. Arrows represent direction of movement for corresponding body segments. (B) A map of Peru showing the four field sites. (C) A schematic of the pop-up behavioral arena used to collect thrashing videos.

The team first recorded how often snakes responded to stimuli with a thrash dance. Certain species of coral snake were more likely to dance than others and smaller snakes were more likely to do a thrash compared to larger individuals, regardless of species. The researchers also found that snakes were more likely to thrash dance when exposed to contact stimuli compared to looming or vibration stimuli. This makes sense as the combination of thrashing and color banding is thought to make it harder for attacking predators to tell where the snakes head is.

Figure 2 Results show the probability of thrash dance response (A) across species and (B) among snakes of different sizes (snout-vent length). (Figure 3 from Moore et al., 2020)

When exploring how the snakes actually perform their thrash dance, this study found some overall similarities in certain features across all species and individuals. In general, trashing duration was similar among all species. Additionally, all species had more curvature and tighter curvature towards the head compared to the body, a behavior known as “neck kinking”.

However, there was more variation among the different species than the team expected. While all species used the neck kinking, different species displayed different curvature along the rest of the length of the body. Additionally, the amount of variation in thrashing curvature was similar to the amount of variation observed in the color patterns among species and individuals. This was surprising as both color and thrashing were expected to converge according to the theory or mimicry.

Take home: what can thrash dances teach us about the theory of mimicry?

Complex anti-predator behaviors, such as the combination of flashy color and thrash dance, are thought to be constrained by stabilizing selection. This choreography of style and substance is thought to signal boost to predators that these “nope ropes” do not mess around! While the coral snakes do follow some of the same steps, this study shows that having personal style on the dance floor may have some additional benefits!

Before you go! Check out the authors video summary of this paper!

Authors video summary of Moore et al., 2020

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