Evolution of the Alligator
One of the most highly evolved animals on the Earth today is the alligator. Found mainly in the swamps and warmer climates of the earth, these predators are one of the few animals left that existed when the dinosaurs roamed the planet. Over the millennia, they have evolved into one of the most feared and interesting creatures today. However, the modern alligator is a far cry from its ancestral roots.
Today, by looking at the anatomy of the alligator there are many similarities between alligators and humans. (Jones, 2011) Most of their internal organs are located in roughly the same place as a human. The liver and spleen are just above the stomach while the intestines are below, and their spine runs down the middle of their back. The most interesting feature of the alligator is the mouth. The most noted feature often is the long nose and mouth. The nose and mouth is long for two reasons. First, it allows for the alligator to breathe while the rest of his body is underwater, and second to handle the force load of its powerful jaws when it closes. The bite of an alligator has been measures at over 2,100 pounds. That’s the equivalent of a car landing on top of a human. (Viegas, 2003) The mouth has evolved of the centuries to handle the pressure exerted.
It is believed that alligators were first primarily land creatures that ranged in size from cats to bears. At the time, there were also some species that lives mostly on plants rather than animals. In both cases, they had two unique openings in their skull that compensated for the powerful bite. (RomerianReptile, 2009)
The alligator started to leave their land based homes for more marine live around 200 million years ago. This brought about the most visible change in alligator physiology. Their bodies became longer and their limbs were spaced out more to help move in the water, and this habitat change also led to what we see today of the long, flat snout and powerful jaws. When alligators first left the land, they had a hard time eating fish and other marine live due to living in shallower water and lack of movement in the water. There was, however an ample supply of animals that would come to the water to drink. In order to hunt the animals, their noses became longer to encase more of the prey in their jaws and the bite grew more powerful so as to incapacitate the animal and lessen the chance of escape. Also this was the time where the species grew to enormous sizes, imitating their dinosaur cousins. However, these “super crocs” were believed to have died out due to the extinction event that also claimed the dinosaurs. It is interesting to note that even though the “super crocs” may have been wiped out, but the smaller version we see today did survive the event.
Two other characteristics we see today in alligators are their hard top skin, and long tail. Since the alligator is cold blooded, it uses its skin to help regulate its internal temperature. Since it spends most of its time in the water, the top of the alligator is darker in order to absorb the sunlight while on land or in the water. While in the water, the alligator can position its body on the top of or completely underneath the water while keeping its head and eyes on the surface. This allows the alligator the ability to obtain heat from warmer pockets of water under the surface while still being able to breath. This is how many believe the alligator can survive temperatures of almost freezing. (Orobello, 2012)
The tail is one part of the anatomy that has had little change over the centuries. The tail accounts for about half of an alligators total length. The tail is used primarily for movement in the water and for defense. When hunting or defending itself, one can see where the alligator will bend its body towards its target and slinging its tale at the object. If hunting, its objective is to knock down its prey to easily subdue them, if defending, it’s to knock down so it can use its primary weapon, its mouth, to kill or injure the attacker and escape. The tail is also covered not only by the hard outer skin but also small protrusions along the top and sides that cover the alligator as well.
Today, the alligator is only threatened by man and his desire to expand over the dry land. At one time they were considered endangered, but with new laws and federal protection of their land the alligator has flourish and is not even considered threatened. I have heard it said that the only things to outlive humans were cockroaches, but since they have survived throughout the millennia, one can assume that alligators could also survive almost any event and still thrive.
References
Jones, S. (March 18, 2011). Reptiles 5. Retrieved from http://rjfisherjoanides.pbworks.com/w/page/36530159/Reptiles%205
Orobello, N. (2011). Thermoregulation and its Effects in the American Alligator. Retrieved from http://www.bio.davidson.edu/people/midorcas/animalphysiology/websites/2011/Orobello/Index.htm
RomerianReptile. (September 9, 2009). Evolution of Alligators and Crocodiles. Retrieved from http://romerianreptile.hubpages.com/hub/Evolution-of-Alligators-and-Crocodiles
Strauss, B. (October, 2012). Prehistoric Crocodiles - The Ancient Cousins of the Dinosaurs. Retrieved from http://dinosaurs.about.com/od/typesofdinosaurs/a/crocodilians.htm
Viegas, J. (September 15, 2003). Scientists ID Strongest Animal Bite. Retrieved from http://animal.discovery.com/news/briefs/20030915/alligator.html
