Snake Secrets: Their Hidden Legs and Crazy Diets, Explained (2023)

There is no doubt that snakes have captured our imaginations throughout history. They are adored and feared, and they often appear in fairy tales and myths, whether they are depicted as the long hair of Medusa or the guardians of the water.

Unfortunately for snakes, however, they have a bit of an image problem. That's a shame because persecution, habitat loss, pollution and climate change all have an impact on snakes, which can lead to a decline in snake populations.

jump to:

  • What is a snake?
  • What is the largest snake?
  • What is the smallest snake?
  • What do snakes eat?
  • What is venom made of?
  • How long do snakes live?
  • What is the life cycle of a snake?
  • How do snakes mate?
  • Do some snakes really have vestigial legs?

What is a snake?

Snakes, along with their close relatives the lizards and worm lizards, belong to a group of reptiles known as "squamous reptiles." There are more than 4,000 species of snakes. These adaptable animals have evolved to occupy a variety of habitats, including forests, oceans, wetlands, trees and deserts. In fact, the only continent they don't inhabit is Antarctica.

Snakes are ectothermic, meaning they cannot generate their own body temperature and must gain heat from their surroundings. You may see snakes basking in the morning sun to warm their bodies so they can be active. If it gets too hot, they seek shelter so they don't overheat.

Snakes don't have limbs, although some snakes do have "degenerate limbs" - more on that later. They don't have movable eyelids; instead, their eyes have a clear scale called a "brille" (similar to a contact lens). When they shed their skin irregularly, their fur also sheds. They have no external ear openings and have forked tongues, which allow them to "taste" the air to find prey.

What is the largest snake?

The longest snake in the world

The longest snake in the world is the reticulated python.

"There are rumors about how big they are. They can grow to about 9 or 10 meters," saidProfessor Mark O'Shea, a herpetologist at the University of Wolverhampton. "But they're not heavy, a very large female - because females are bigger - maybe 75kg."

heaviest snake in the world

The heaviest snake is the green anaconda. They may reach 8 meters in length, but large females can reach 100 kg.

"That's because anacondas are aquatic snakes," O'Shea said. "The water supports their weight."

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What is the smallest snake?

The smallest adult snake is the Barbados blind snake. It is only 10 cm long.

"It's actually a very endangered little snake. It's an earth snake and it burrows. It doesn't really have eyes, all eyes see it when it's exposed to light. Unless it's raining, you You don't usually see them coming out and moving around because they eat termites and larvae underground," O'Shea said.

"It's endemic to Barbados and only three specimens have been found. It could be a rainforest species that lives in rainforest termite mines, but Barbados has lost a lot of rainforest."

What do snakes eat?

Unlike lizards, which may be vegetarian or omnivorous, snakes are completely carnivorous. They will eat a variety of foods including invertebrates, fish, amphibians, other reptiles, birds and their eggs or mammals. While some snakes specialize in eating specific foods, others can eat a wide variety of prey - whatever they can fit in their mouths!

Some prey, such as invertebrates, small fish, or frogs, may not need to be killed before swallowing, as the snake will swallow them.

However, other prey may need to be subdued first because they are too large or dangerous to swallow alive. That's where snakes evolved two ingenious systems to deal with trickier prey: constriction and venom.

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Constriction is when the snake coils itself around its prey and tightens its grip until the prey dies. "The constriction isn't bone crushing, it's not suffocating. It actually kills the prey because the coils are so tight they stop circulation and the prey die of a heart attack. And it can be very fast. It's amazingly fast. The constriction is very fast It would be fatal," O'Shea said.

Nonvenomous snakes, such as boa constrictors, pythons, or corn snakes, have simple, sharp teeth that point backwards to prevent their prey from escaping. But the teeth of snakes that use venom are quite different.

Posterior snakes have a pair of fang-like teeth at the back of the upper jaw. These teeth have grooves through which venom can drain. Since the venom is delivered from the back of the mouth, it's a more laborious process, which means these snakes tend to feed on smaller prey that can't cause serious pain or injury to humans. However, there are some exceptions. One of them is the Buslan snake, an arboreal snake from Africa that can kill people.

There are also snakes, such as cobras, mambas, and coral snakes, that deliver their venom through a pair of large, fixed fangs at the front of their mouths. They have a channel in the center that delivers venom to the tip of the fang and then into the prey. These snakes usually bite their prey and hold on until the venom takes effect.

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And finally there are vipers, which have extremely long articulated fangs that swing forward to quickly inject venom deep into their prey. The rapid delivery system means that the snake can move out of harm's way after biting its prey, and then wait for the prey to die before entering the engulfment.

The venom is primarily used to subdue and kill prey, but snakes will bite defensively if they feel threatened. However, a group of snakes, the spitting cobras, use their venom to deter predators. Interestingly, the study was published in the journalscienceIn 2021, discoverThe emergence of the African spitting cobra appears to have coincided with the evolution of bipedal hominids. The researchers speculate that snakes may have begun spitting venom into the eyes of early humans as a form of defense.

What is venom made of?

"Venom is a complex mix of enzymes and proteins. There's usually more than one type in a particular snake," O'Shea said.

The venom may be neurotoxin, attacking the nervous system and muscles and may cause paralysis. There are also venoms that affect the blood and circulatory system, causing clotting problems. Others damage tissue, causing pain and cell death. Some attack organs, such as the heart or kidneys.

Venom composition is highly adaptable, with individual snakes of the same species using different mixtures depending on their age, habitat or prey.

Learn more about snakes:

  • Snakes of the plains: Dinosaur-killing asteroid impact led to global surge in snake species
  • What evolutionary advantage did snakes gain by losing their legs?

How long do snakes live?

Apparently, there are thousands of species of snakes, and their lifespans vary widely. What we do know, however, is that captive or pet snakes tend to live longer than wild snakes. A pet royal python, if cared for properly, can live 30 years or more, and in the wild they are lucky to live 10 years.

Snakes in the wild grapple with food shortages, predation, human impact, habitat loss and greater temperature fluctuations, all of which affect their lifespan.

The oldest surviving captive snake is Anne the green anaconda, born on July 1, 1983.

What is the life cycle of a snake?

Unlike the amphibians from which they evolved, snakes don't need to return to the water to reproduce.

Most snakes are oviparous, which means they lay eggs. Snake eggs have a tough outer shell, and usually the female snake will lay her eggs in a hidden place and leave. However, some snakes do display maternal care. For example, throughout the egg's development, the python mother wraps her body protectively around the egg and even raises her body temperature slightly to aid in hatching.

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Other snakes are viviparous and keep the embryo inside throughout development. The females give birth to live hatchlings, which are born encased in a transparent sac from which they emerge and glide to live independently.

Viviparity has some advantages and disadvantages. On the plus side, the baby snakes are protected throughout development, with the female serving as a mobile incubator. But the downside is that if a female is killed, all her offspring die with them. She may also have difficulty eating because most of her body is occupied by the baby.

But viviparity does mean that snakes can venture into regions that are too cold for egg-laying snakes.

"Grass snakes have a range as far south as Scotland, while the northern adder, the only venomous snake in Britain, can live as far as the northern tip of Scotland and some parts of the interior of the Hebrides. The viper is so widespread that the grass snake The reason they're stuck in southern Scotland is because of their breeding," O'Shea said.

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"Grass snakes lay their eggs in a warm place, like a compost heap or something like that, and they leave their eggs. If it gets colder, as it is in the north of Scotland, the eggs may not survive. But vipers will give birth. young snake, so she can move around in warm weather or hide in cold weather. She is better adapted to colder climates. The northern adder is actually the most northerly distributed snake in the world. It is found in the Norwegian Arctic Found north of the circle."

The number of pups varies widely and is highly species dependent. Snakes can have as few as one offspring, as either egg-laying or living carriers, and as many as more than 50.

Once hatched or born, baby snakes can live on their own and become fully capable hunters.

How do snakes mate?

Generally, there is not much difference between the sexes of snakes and it takes an expert to tell them apart. There are exceptions (because nature is never simple!), such as the aforementioned green anaconda and reticulated python, where females are larger than males.

When a female snake is ready to mate, she leaves a trail of pheromones. The male snake will follow this path, using its forked tongue to detect chemicals.

Of course, he might not be the only male keen to mate with females. In some species, males may congregate in large numbers around females. For example, red-sided garter snakes form mating balls in which 10 or more males surround one or two females.

The sex of snakes is internal, and male snakes have a pair of penises called "half penises". Generally, they are hidden in his body and are located at the base of the tail.

"The snakes only evert when they're going to mate," O'Shea said. "Since he usually crawls on his belly, he won't be using it for very long if the penis is outside the body!"

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The male will then crawl along the female's back in courtship and caress her body. He'll try to encourage her to lift her tail so he can insert a half-penis into her reproductive opening (cloaca).

Some snakes have slightly different methods of courtship. For example, those species with vestigial limbs may use these appendages to caress females. Elsewhere, the glans-headed sea snake has a special scale on its snout, which it uses to tickle the female's back.

Do some snakes really have vestigial legs?

Snakes evolved from animals with four limbs. Snakes are not easy to fossilize because their bones are rather fragile, but there is evidence that they first appeared during the Jurassic or Cretaceous period.

While many snakes have completely lost traces of their limbs, pythons and boa constrictors have tiny remnants of their hind legs, almost visible from the base of their tails. These may be larger in males and are used in courtship of females.

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Research published in journalmodern biologyIn 2016, foundBoa constrictor and boa constrictor embryos initiate hindlimb bud formation, but the development of the legs does not continue, resulting in immature femurs and paws.

About our expert Professor Mark O'Shea

Mark is Professor of Herpetology at the University of Wolverhampton. He was curator of reptiles at Midland Wildlife Park for 33 years and presentedO'Shea's Great AdventureWorked on Animal Planet for five years. He conducted several scientific expeditions to study reptiles and was involved in snakebite research. He was awarded an MBE in 2020.

He has written many books on reptiles. His latest work,snakes in the world(£25, Princeton University Press), now available.


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