All snakes are carnivores. They are neither omnivores or herbivores. Whilst their diets differ depending on the species, they all eat meat and generally avoid plants.
Some snakes prefer warm-blooded prey such as rodents, birds and rabbits whilst others prefer insects, amphibians, eggs, fish, reptiles and earthworms.
Why are Snakes Carnivores?
Snakes have evolved to need meat in their diets. Furthermore, they now only see meat as potential food. It doesn’t even cross their minds to eat plants!
Snakes tend to eat their prey whole. When prey is swallowed whole, snakes get everything they need and receive a balanced meal.
They have very strong stomach acid that can break down tissue and even bone. This means that a rodent, for example, eaten in full, will provide a snake with a complete nutritional meal.
This is the main reason that evolution wise, snakes haven’t needed to develop the requirement to digest vegetables. They are able to use their astringent stomach acid to digest everything from skin and tissue to bone and muscle.
No known snake species in the world today feeds on plant matter, not even partially.
Other reptilian species such as lizards and the marine iguana have been observed eating plant matter from time to time. Even crocodiles enjoy a semi plant-based diet, which provides them with a lot of vital nutrients.
Their Carnivorous Physiology
Snakes are known to have extremely wide skulls and elongated teeth or fangs. Their whole physiology is built to swallow prey whole.
Snakes are known to swallow prey that is often larger and a lot heavier than themselves. This leaves snakes with teeth that aren’t suitable for chewing, especially breaking down vegetation.
One of the ways that herbivorous animals introduce microorganisms into their food is through their saliva. The process of chewing breaks down the vegetation and the microbes within the saliva work their way into the gut which helps to break down vegetable matter. But snakes don’t chew, which makes it hard for them to eat vegetation!
The structure of the gut also plays a big role in defining the carnivorous nature of snakes.
Their bodies are relatively small and don’t have enough space to house a complex organ system. They simply don’t have the space to house the varied microorganisms essential to herbivory.
Why aren’t Snakes Herbivores or Omnivores?
Snakes haven’t evolved to consume plant material yet. They don’t have the correct microbes in their guts, and they don’t chew!
Herbivores process the plants that they eat in a very different way than carnivores do. They can’t digest food with a high cellulose content and instead rely on unique symbiotic bacteria that break down indigestable vegetation. Herbivores aren’t able to produce vital cellulase enzymes to break down the cell walls of cellulose and provide energy.
The symbiotic relationship that evolved in herbivores hasn’t yet reached the kingdom of snakes.
The beneficial microbes that live inside the stomachs of herbivores are passed down generationally, usually from a parent. These microbes can also be passed on through other closely associated group members by birth, nursing and coprophagy.
Fun Fact: Their Solitude Feeds their Carnivore Diets
Interestingly, solitary creatures like snakes are often exclusively carnivores. This is because social groups are often required for the species to start developing microbes that help break down vegetation (This often begins through the process of coprography – eating each other’s dung!)
Its well documented that snakes aren’t the most social creatures. In the reptile kingdom, they are amongst the least sociable of the lot. Snakes prefer to be alone and get most of their work done in the cooler evening hours.
Lizards have been known to express social behaviors that have encouraged the development of microorganisms in their guts, which allows them to eat vegetation. Herbivores have developed over the centuries because of the vital role of microbe sharing.
Snakes aren’t sociable enough to allow for vegetation-deconstruction microbes to colonize their guts. Herbivorous animals that are similar to snakes such as lizards and iguanas have complex social interactions that allow for crucial microorganisms to develop in and around their habitats.
Related: Do Snakes have Friends?
Is There Evidence of Omnivorous Snakes?
Vegetable matter has been known to turn up in snakes feces from time to time but this is most likely due to accidental ingestion.
Snakes aren’t fussy eaters, especially when there is a lack of food and they will often eat entire animals whole. This means that the animal, along with its stomach contents are somewhat digested by the snake.
Whilst the meat and bone are dissolved and absorbed by the snake for nutritional benefit, the vegetable matter inside the animal is left undigested and passed as a waste product. This means that vegetable matter has no inherent value to snakes because they can’t digest it.
It’s a waste of time and energy for snakes to eat vegetation and, likely, they’ll only attempt to do so if the vegetable matter smells like animal products, such as seaweed or kelp.
The Harvey Lillywhite Study
In 2008, Harvey Lillywhite discovered that some pit vipers living in the intertidal zone eat seaweed. But, it seemed to be accidental. They mistook seaweed for fish!
He found that the pit vipers were eating seaweed because it smelled like fish. In this case, the snakes couldn’t tell the difference between animal and plant and consumed the seaweed although it offered them now real health benefits.
This study shows that although snakes can eat vegetation (in rare cases) they are hard-wired to be carnivorous in nature.
Snakes are instinctually attracted to the scents of other animals and can obtain everything they need from ingesting their prey whole.
The study supports the understanding that snakes haven’t needed to evolve a herbivorous nature because they have rarely experienced a lack of food.
Food scarcity usually adapts the eating behaviors of animals. Snakes simply haven’t developed into herbivores because they already have everything they need to survive.
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Snakes are built to hunt and swallow their prey whole. They come in many different shapes and sizes and thus have different techniques when it comes to hunting and catching their prey.
Whilst all snakes diets vary, they have an extraordinarily adapted carnivorous nature in common. They are unique creatures who haven’t needed to evolve and take advantage of the herbivorous gene to survive.
This makes snakes an evolutionary marvel and one of the most unique and well adapted predatory species on the earth today.
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