Evolution is about adaptation. It’s nature’s way to transcend boundaries, to react to the stimuli of life; to make every cell in an organism run at its most efficient in order to assure survival. Evolution is the lubrication of life and without it, organisms would sieze, just like an engine, and ultimately fail. However, certain animals have remained unchanged for potentially hundreds of millions of years. The only way this is possible is if they have already reached what is considered evolutionary perfection and therefore nature needs no reason to select them for change. Bushwise sheds some light on one such species that has remained unchanged for years, the crocodile.
The first ancestors of the current day Nile crocodile evolved in a world very different to our own. 250 million years ago, they roamed the planet alongside the mighty dinosaurs, yet somehow they managed to survive the mass extinction that ended this reptilian domination. Crocodiles are considered living relics of this bygone era and if one delves a little deeper into their physiology, one can begin to understand why they are still so successful, despite all the changes that have since impacted the world.
The beating heart of any vertebrate is, well, its heart. This is the engine that drives every other organ in its body and just like a car manufacturer; those with the best and most efficient hearts tend to be more successful. It is no surprise then that crocodiles have what is considered by many, to be the most advanced heart of any animal known today.
Unlike all other reptiles, Crocodiles have 4 chambers in their hearts instead of 3. In simple terms, this means that their circulation system is closed and that oxygenated and deoxygenated blood does not mix. This makes the heart far more efficient and thus the engine can produce a lot more power for the same effort! This does not mean that a crocodile’s heart resembles our own however… What makes it even more unique is a specialsed organ known as the Foramen of Panizza. This may sound like an Italian pizza shop owner but it is in fact a specialised valve that can regulate where the blood is channeled in the body.
Let’s take holding your breath for example. The reason, that after a minute or so of being submerged, you need to resurface is because the oxygen in your blood has been used by organs such as your brain and muscles and needs to be replenished. A crocodile is able to hold its breath for well over an hour in the right conditions. How is this possible? Well, for one thing it is able to reduce its heart rate to only a few beats per minute in times of inactivity. But the real answer is the Foramen of Panizza. Instead of blood being pumped into the lungs and thus wasted on an organ that is not in use, they are bypassed so that the blood can be sent to more important areas (i.e. the brain and tail), and thus be used much more efficiently.
Other than their mastery of aquatic living, the crocodile is a ferocious and non-selective hunter. Not concerned with taking only the choice cuts, a crocodile’s incredible digestive system is able to process not only meat, but also fur, horn and even bone. How it is able to do this is also directly related to the Foramen of Panizza.
Deoxygenated blood cannot be re-oxygenated by the inactive lungs whilst the animal is submerged. However, carbon dioxide is an important chemical ingredient in gastric juices and thus in efficient digestion. Therefore, instead of wasting the carbon dioxide rich blood, the Foramen of Panizza redirects it to the stomach in order to create more digestive enzymes. This means that any protein rich food can be converted into energy. Only small amounts at a time can be fed into the intestines however and in many animals, the meat being stored in the stomach would putrefy due to an excess of bacteria. The acidity created by the excess CO2 minimises this risk and thus enables a crocodile to digest a large meal slowly over a prolonged period of time. In a world where you never know where you next meal will come from, or what it will be, these are perfect strategies for survival!
Perfection is a strong word and one that is thrown around with all too much ease but the crocodile is more than worthy of this tag. Ancient humans began to walk on two legs about 5 million years ago and look how much we have changed in that time. Crocodilians have been major players in the game of life for close to 50 times as long and have barely altered… Surely this is evidence that perfection exists?!