Last month we saw this American Crocodile (Crocodylus acutus) in the lower reaches of the Rio Cuero, Honduras, just about in the centre of its geographical range.
The American Crocodile prefers the somewhat saline waters of estuaries and mangroves and in this respect resembles the Estuarine or Saltwater Crocodile (C. porosus) of south-east Asia and northern Australia, a story I will return to in my Salt Glands Revisited series. It is also one of the largest species of crocodilian.
Basking with the mouth open—and thereby showing their very impressive set of teeth—appears to be concerned mainly with thermoregulation. Under the sun the head warms more quickly than the bulky body. Evaporative cooling from the tissues lining the mouth will lower the temperature of venous blood leaving the head. Provided there is a countercurrent arrangement whereby arterial blood entering the head is cooled by the venous blood passing in the opposite direction the brain will be kept relatively cool while the rest of the body gets to the optimum temperature. That’s the standard story but I have not checked whether or not there has been any experimental demonstration of the cooling in action. The reason I wonder, is that if, during basking, the blood from the body is relatively cool why the high rate of blood flow to the brain does not also keep the brain cool without the need for evaporative cooling? Or does the head get so hot that cooler blood from the body is insufficient to prevent the brain from suffering heat damage? Somebody who knows a lot more about crocodiles and their thermal physiology will put me right.
We asked if the crocodiles were dangerous to the human population especially the children. We were told not. Salties or Nile Crocodiles they are not.
George Cuvier in 1807 was the first to describe the American Crocodile but considered it another species of alligator. It took another Frenchman, the brilliant but mercurial Constantine Samuel Rafinesque, then working in the USA, to suggest in 1822 that it was not alligator but a crocodile.
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| Crocodylus acutus Distribution Achim Raschka BB BY-SA 3.0 Wikimedia Commons |
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