The crocodile arose over 200 million years ago, surviving 65 million years longer than the dinosaurs. Although scientists are not certain why the crocodiles were able to outlast the dinosaurs, what is certain is the crocodiles’ efficient adaptation to their respective environments. Besides a thick protective exterior, crocodiles have an amazing immune system. This immune system enables them to sustain traumatic injuries, from which other reptiles and animals would not be able to recover. They have proteins in their blood that can destroy bacteria that is even resistant to penicillin. Because of their strong immune system, scientists are working towards using their blood in order to synthesize antibiotics for humans. Crocodile serum is also able to resist the HIV virus more readily than human antibodies. Scientists are hopeful that this may lead to the discovery of antibiotics for HIV.
Another survival feature of the crocodile is their ability to go for long periods without food. This is because crocodiles are cold-blooded and therefore do not require as much energy as warm-blooded animals. Crocodiles eat as much as they can when food is plentiful. They hide and wait for prey to swim by before striking. This also helps crocodiles conserve energy. They do not chew their food, but swallow it whole. Once food reaches their stomachs, their digestive system breaks food down, and is so acidic, they are even able to digest bones, horns, and hooves.
Their highly efficient digestive system consists of two stomachs. Their first stomach, called their muscular stomach, minces their food. Crocodiles swallow stones that remain in this stomach and aid in this process. Second, their food melts in their highly acidic glandular stomach. When food is not available, crocodiles survive off stores of energy in their tissues. In fact, crocodiles can survive up to a year without food!
Another unique feature that separates crocodiles from other reptiles is their four-chambered heart. Scientists hypothesize that their heart’s capacity for separating oxygenated blood from non-oxygenated blood, allows crocodiles to stay submerged under water for over an hour. Their heart has an extra valve that closes in order to stop blood from returning to the lungs right away. Another hypothesis concerning this function is that this blood flows to the crocodile’s stomach to aid in digestion. Blood that is rich in carbon dioxide digests food faster and more efficiently because carbon dioxide is a building block of stomach acid.
Female crocodiles lay between 20 and 90 eggs at one time. After 80 days, the mother crocodile carefully cracks her eggs in her mouth to help them hatch. Their sex is not genetically determined, but rather determined by the surrounding temperature. Temperatures below 31.7 or above 34.5 degrees Celsius produce female crocodiles while temperatures between 31.7 and 34.5 degrees Celsius produce males.
Female crocodiles are very protective of their young. When threatened, females hide her young in a pouch inside their throat called a gular. Depending on the species, baby crocodiles remain with their mother from a few months to a several years. Crocodiles are social animals and often remain in groups even after reaching adulthood. They live an average of sixty to seventy years old. Despite predators and poachers, none of the twenty species of crocodiles are extinct, a testament to the crocodiles’ endurance through the ages.
