• Isaac yelchin

Venomous Mimicry

We live in a biodiversity hotspot known as the floristic province, that is filled with endemic plant and animal species. Endemic means that these species are originally from an area and only exist in that area. So hiking through Southern California is an experience like no other. The majority of these plant and animal species are exceptionally friendly. Unlike many other biodiversity hotspots around the world Southern California only has a handful of dangerous species. In Costa Rica for example, there are 23 venomous snake species and here in California there are only rattlesnakes. Although there are a number of species of rattlesnakes, the identification of them is standard, and they will warn you of their presence.

First let's start with the identification of a rattlesnake. These snakes are pit vipers which means they have organs in their head, referred to as pits. These pits are able to sense infrared, or a heat map. This allows the snakes to see the heat given off by prey items or by the sun, and help the snakes in hunting and locating places to thermoregulate. For example, let's say a rattlesnake is looking for prey, in this case a ground squirrel, the snake will stick its head into a burrow and look for traces of heat. These burrows can be deep and dark and with only normal vision the snake might not be able to tell that a ground squirrel is hiding in the back of the tunnel, however using its infrared pits it will be able to sense the heat the squirrel is emitting and locate it that way. It is said that rattlesnakes can even sense the heat left from an animal passing through, so it can sense the heat that was transferred to the ground in the form of footprints. These infrared sensing pits are what allow the rattlesnake to be easily identified.

As you can see in the image below, (Gopher snake on left and Rattlesnake on right), the pits protrude from the rear of the head and give the rattlesnake a triangle shaped head. You can compare this to the gopher snake, who has a very similar camouflage pattern, feeding and sunning habits. But has a different shaped head without the infrared sensing pits. Looking at the shape of the head is the only way to properly identify a gopher snake, as sometimes rattlesnakes can be mutated and have no rattle.

The gopher snake is so similar to the rattlesnake that it relies on these similarities to confuse predators. They have the visual adaptation of similar patterning to ward off predators thinking that the gopher snake may be a rattlesnake based on coloration. Predators of snakes, hawks, coyotes, owls, and the like would prefer to eat a non-venomous gopher snake. So if a gopher snake can pass off as its dangerous cousin it has a higher chance of survival. However, the most interesting mimicry that the gopher snake employs is the behavioral adaptation that the gopher snakes have developed.

The story I am about to tell involves me picking up a gopher snake, which is not recommended unless you are a trained professional. I have spent my whole life studying reptiles, particularly those local to southern California and only handle snakes if I am concerned about an injury or to collect scientific data. There was a young gopher snake near my home and I went to pick it up to see if it was in good health. I lightly grabbed its tail to hold it in place while I inspected it. Suddenly its tail started to shake in the same way that a rattlesnake rattles. Scared, I let go and backed away, which gave the gopher snake time to make an escape.

This fascinating adaptation is one that utilizes the similarities in markings to make the predator cautious and then uses the behavior of a rattlesnake to completely fool its predators, or in this case fool a caring herpetologist. Keep these behaviors and identification skills in mind next time you go hiking and you may see snakes in a whole new way.

Isaac Yelchin is foremost a herpetologist. He studies lizards, frogs, newts, and the like. Specifically, he spends all day and night thinking about what it is like to be an animal. What are the animals thinking about? What is their perspective? When he should be working, he sits and stares at his pet lizard asking himself these questions.

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