In the animal kingdom, snakes always evoke curiosity due to their mysterious and captivating appearance. However, have you ever wondered why snakes lost their legs throughout their long evolutionary process?
Ancient snakes, dating back approximately 150 million years, actually had legs. However, as we clearly see today, snakes either have no legs (such as cobras and vipers) or possess small vestigial limbs (like the South American boa).
So, what happened from 150 million years ago to today?
Evolutionary Reasons Behind Snakes Losing Their Legs: Habitat Changes and Survival Needs
Researchers from the University of Florida, USA, have identified a gene they excitingly named Sonic the Hedgehog, which controls limb development in snakes (and all vertebrates with legs). Upon identifying this gene, the researchers observed quite a lot of unusual activity.
While all vertebrate animals possess the “Sonic The Hedgehog” gene, in snakes, this gene appears to be absent. Even more strangely, this gene only appears briefly during the embryonic development of baby boas, particularly in those under 24 hours old. What does this mean?
We can draw several conclusions from this unusual activity of the Sonic The Hedgehog gene.
The main conclusion is that the brief appearance of the Sonic The Hedgehog gene during the embryonic development of baby boas is responsible for the small vestigial legs they have left.
In the evolutionary past, the ancestors of snakes had four legs, allowing them to move freely on land. However, over time, some snake species began to lose these legs and evolved into a legless body structure. This evolution of body structure was not a sudden event but rather the result of gradual development over millions of years of evolution.
A key reason for this is the changes in the habitat of snakes, which forced them to adapt to new living conditions. Some snake species live in caves and trees, while others inhabit diverse geographical environments such as deserts and wetlands. The terrain in these environments is highly varied and sometimes constricted, leading to snakes adapting to these new living conditions by losing their legs, which helps them move easily through narrow spaces.
The flexible nature of a snake’s body is one reason they easily adapt in tight spaces. Their spinal structure and the way their ribs connect allow snakes to perform special postures, such as coiling or bending. This enables snakes to move freely through various confined spaces, and even thicker-bodied snakes can pass through narrow gaps.
Legless snakes are also related to their food chain. Snakes survive by hunting other small animals, so they need agile and swift bodies to chase their prey. The speed and agility of their prey may have surpassed what could be achieved with four legs, leading snakes to gradually lose their legs and evolve a more flexible body structure.
Further research shows that some snakes still retain vestigial leg bones after losing their legs, indicating that they once had four legs, though these limbs have become progressively smaller over time and eventually completely degenerated. This degeneration illustrates the adaptability of snakes throughout the evolutionary process. Snakes actively degenerated their legs in evolution according to their needs, no longer requiring four legs to adapt to their living environment and hunting requirements.
Their relatively small heads allow snakes to easily navigate through narrow gaps that other animals cannot fit through. Additionally, their scaly skin provides strong protection, helping them avoid injury in small spaces.
The Evolutionary Process of Snakes: From Limbs to No Limbs
Ancient snakes had limbs in their physiological structure. The primary function of these limbs was to aid snakes in better locomotion and the ability to grasp prey. The existence of limbs made ancient snakes more agile when moving and hunting, allowing them to adapt to the needs of their environment at that time.
However, over time and with environmental changes, snakes began to gradually adapt to a legless lifestyle. This process was primarily influenced by two factors: environment and genetics. Environmental changes rendered limbs unnecessary for snakes’ survival and reproduction. Concurrently, gene mutations caused some snake species to gradually lose their limbs, and this change would be passed on to future generations.
Snakes have also learned to use their keen senses to navigate in tight spaces. They have developed a sophisticated system of smell, touch, and hearing, allowing them to detect subtle changes in their environment and quickly execute corresponding movements. This perceptual ability enables snakes to move efficiently in confined spaces and promptly avoid potential dangers.
Over time, the bodies of snakes have grown longer, and their limbs have gradually degenerated. Throughout the evolutionary process, the skeletal structure of snakes has undergone significant changes. Their forelimbs and hind limbs have gradually shrunk and disappeared, ultimately degenerating completely. During this process, the muscular structure of snakes has also adapted to a limbless lifestyle, allowing them to slither on the ground through the friction of their belly scales.
Modern snakes have fully adapted to a legless lifestyle. Their body structure is highly flexible, allowing them to adapt to various environments and small spaces. The movement of snakes primarily relies on strong abdominal muscles and the motion of their belly scales to crawl on the ground.
The species of snakes have undergone 26 challenging evolutionary changes and lost their legs, prompting humans to contemplate evolution and the meaning of life. This evolutionary process seems to remind us that life is not easy and requires hard work and sacrifices to achieve improvement and progress. Just like snakes, we will encounter countless difficulties and challenges in our life journey, but it is these challenges and hardships that shape our character, willpower, and drive us to continuously surpass ourselves.
