Springtime Snakes

With warmer weather comes a plethora of ectothermic animals in Massachusetts that rely on the outside temperature to regulate their internal body temperatures. In the wild, ectothermic animals get heat energy from the sun. Fish, amphibians, reptiles, and invertebrates are the ectothermic animal groups. Birds and mammals are endothermic, which means they can produce their own body heat and maintain a constant temperature. We can find fish, reptiles, amphibians and invertebrates throughout Massachusetts, but they become much more obvious as soon as the weather warms up.
 

One of my favorite signs of longer days and hotter afternoons is the sound of snakes slithering away as I walk various hiking trails. These legless reptiles will often make their way onto paths between forests and fields to bask in the strong midday sun. Many people find snakes to be a little bit scary, but in reality, these stealthy animals are pretty harmless, especially in Massachusetts, and should be more worried about us than we are of them.
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Snakes are often depicted in books, films and throughout history as having some kind of mystery associated with them. The serpent is one of the oldest and most widespread symbols in mythology and perhaps one of the most well-known symbols is that of the serpent eating its own tail in ouroboros. The first documented depiction of ouroboros spans all the way back to the 13th century BC, where this image was portrayed on the tomb of King Tut. It’s clear that the snake, or serpent, has left humans fascinated for hundreds of years, but what is it that makes them so intriguing?
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Snakes are fairly elusive during the day and many of them are even nocturnal, meaning that they only come out at night. Because they are difficult to see and wonderful escape artists, they aren’t the first animal that comes to mind when we think of Massachusetts. Surprisingly, there are actually a total of 14 species of snakes that can be found throughout the state!

What is it about snakes?

​Where are their legs?!

The first thing we notice about snakes is that they have no legs, but up until 150 million years ago, snakes actually did have legs! Some snakes even have a pair of vestigial legs that appear as tiny bumps on the animal’s pelvis. A vestigial feature is a trait that an animal has that no longer serves a function. Many times, the bone structure of animals will reveal vestigial features that can be clues to what these animals used to look like and how they evolved over time. By looking at gene expression in snakes and vestigial appendages, scientists can start to understand how they lost their legs over time.

When an animal group evolves, one reason can be because individuals with specific traits are more successful and better able to survive. Can you think of how not having legs could help a snake's survival in the wild? What are some things that they may be able to do more easily because they don't have legs? What could be a disadvantage of not having legs?

Why are there so many deflated snakes on the ground?!

Another intriguing thing about snakes, and all reptiles, is that they never actually stop growing! Each snake species has an average size that they reach at maturity, but they will never truly stop increasing in size. The rate at which they grow dramatically decreases once they reach maturity, but as long as they can continue to eat, they will continue to grow. We can see this happen when snakes shed, which is just another very cool and slightly mysterious thing that snakes do. Interestingly enough, all animals (even humans!) shed throughout their lives, we just don’t do it all at once like the snake. Unlike humans and other animals, a snake's skin will stretch, but cannot grow with the snake. When the snake skin is no longer able to stretch with the snake, it will become a shed and the snake will wriggle its way out. Many of us have come across snake skins in the wild and they can be a little bit unsettling if you aren’t sure what they are. The more a snake eats, the more it will shed, but on average, snakes shed about 2-3 times per years. Perhaps the ability to completely shed their skin and “transform” many times throughout their lives is just another reason that humans have been so fascinated by snakes throughout history.

Some people think of snake sheds to be similar to that of an insect's exoskeleton, which is a hard external covering of invertebrates that gives them protection and structure because they have no bones. A snake shed and an exoskeleton casing look very similar, but snakes actually have many, many bones! A snake can have anywhere between 200-400 vertebrae, or backbones, and two ribs attached to each of those. For comparison, adult humans have 206 bones in their bodies.
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​How can they fit so much inside their mouths??

One other thing that may come to mind when you think of snakes is their ability to stretch their mouths open extremely wide! Snakes are not able to chew their food, so they have to swallow everything they eat whole. When we look at a snake's jaw, the muscle and ligament composition is very different than that of a human, or an animal that chews its food. The tendons in a snake's jaw are meant for flexibility and elasticity, whereas animals that chew their food have strong muscles for chomping.

A common misconception about snakes is that they dislocate their jaws to swallow their food whole, but in reality they don't have anything to dislocate! As mentioned before, snake jaws are built very differently that human jaws and they are naturally extremely stretchy. That being said, you can watch snakes rub the bottom of their jaws along rocks after eating large meals to make sure their jaws are aligned properly. 

There's so much more!

There are a lot of extremely unique adaptations that snakes have, from their coloration all the way to their individual behaviors. There just isn't enough blog space in the world to talk about all of it! Some great resources for looking up snake facts, both locally and worldwide are:

- Mass Audubon's Snakes of Massachusetts
- National Geographic Snake Facts
- Live Science Snake Facts

Snakes can be tricky to spot in the wild, and I often notice them after I've scared them away, but if you keep your eyes and ears open, you may just be able to spot one on your next walk. They love basking in the midday sun to get energy and they are great at camouflaging with their surroundings. Next time you go for a walk on a sunny day, take time to watch the ground near and around where your stepping for any movement!