Alligators are absolutely amazing animals. They have been around for millions of years and are about as close as humans will ever get to seeing a living dinosaur. So how and why have they survived so long? They are nearly perfect animals for their environment, including U.S. states like Florida, Georgia, Alabama and Louisiana.
But wait! There's more ...
- Alligators can survive two to three years without eating.
- Alligators are one of the few reptiles today that care for their young.
- Alligators have vibration sensors on their skin that are extremely sensitive -- they can detect even the slightest vibration and get out of harm's way long before it arrives.
On the other hand, alligators can be quite dangerous. They are instinctual living machines. An alligator's brain weighs only 8 or 9 grams and would take up only one-half of a tablespoon. This lack of brain power means there is no such thing as a "nice alligator". If it's hungry, an alligator will eat anything that moves. Pets and children who wander near an alligator pond are frequent victims of this instinctive behavior.
In this article, you can get up close and personal with these living dinosaurs and understand what has made them so successful for millions of years.
American alligators are reptiles, and they are members of the Crocodylia order. In this order are 23 different species, including the American alligator, Caimans and a variety of crocodiles.
The basic Crocodylia body form has been around for over 180 million years, making alligators and crocodiles living dinosaurs. All of these animals have the same basic layout: big heads, long, lizard-like bodies, four stubby legs and long tails.
Male alligators are, on average, about 11 feet (3.5 meters) long and 600 pounds (270 kg). Females are, on average, about 8 feet long and weigh about half as much as male alligators. Males can actually get much larger -- 1,000 pounds is not unusual. At the Alligator Adventures alligator park in Myrtle Beach, SC, a very large crocodile named Utan weighs in at 2,000 pounds and is almost 20 feet long. He is claimed to be the largest living Crocodylian in captivity. (There is a nice interactive presentation on Utan available at the Alligator Adventures Web site.)
Alligators are fresh-water animals and can be found in lakes, ponds, rivers and irrigation canals. Because they are cold-blooded reptiles, alligators are not big fans of cold weather. This limits their range to the warmer, wetter areas in the southeastern United States from Texas to North Carolina.
While there are reports of one alligator, held in captivity, that lived to be well over 100 years old, something like 40 years might be a more typical old age for alligators living in the wild.
Alligators have a number of special features that have allowed them to stick around for 180 million years.
For example, alligators are armor-plated. Bony plates inside the skin, called osteoderms or scutes, make the skin very hard to penetrate. When you look at the ridges on the back of an alligator, each little spike is made by a piece of bone in that section of skin. Click here to see a photo of typical osteoderms.
Even though alligators are huge and cold-blooded, they can be quite fast, with a top speed of 11 MPH (17 KPH) over short distances. For comparison, the fastest humans running at world-record times in a 100 meter dash, are running about 20 MPH (32 KPH), but a typical adult human is no faster than an alligator. This makes it possible for an alligator to escape from most situations on land and get into the water.
Alligator eyes have two sets of eyelids. The outer lids are like human eyelids. They are made of skin and close top-to-bottom. The inner lids are clear and close back-to-front. While an alligator is sitting about or swimming, these inner eyelids protect the alligator's eyes and provide clearer vision in the underwater environment.
When swimming underwater, alligators are water tight. Flaps close off the ears and nostrils, the inner eyelids protect the eyes and a special flap called the palatal valve closes at the back of the throat to keep water out of the throat, stomach and lungs. Alligators can stay underwater for quite a while. A typical dive might last 10 to 20 minutes. In a pinch, an alligator can stay underwater for two hours if it is at rest. And, in very cold water, an alligator can last up to eight hours submerged.
The Alligator Diet
When it is time to eat, alligators are neither hunters nor gatherers. They are lurkers. They wait for something edible to swim or walk nearby and they lunge at it with incredible speed. Using their tails, alligators can push themselves up to 5 feet out of the water to snag small animals in low-hanging tree branches.
Alligators will eat almost anything they can capture -- fish, turtles, frogs, birds, small mammals, and sometimes even larger mammals like deer. Alligators capture all of these creatures by lurking in the water.
When lurking, only the eyes and nostrils are above the waterline. If it is lurking in the shadows at a pond's edge, this posture can make an alligator impossible to detect. An alligator can sit like this for hours waiting for something edible to wander nearby. When its prey gets close enough, the alligator moves with startling speed.
Besides its eyes and ears, alligators are equipped with skin sensors that are incredibly sensitive to vibration. These sensors make it possible for an alligator to detect anything entering the water or disturbing the surface of the water anywhere nearby.
Once an alligator captures something, it will hold it in its mouth and drag it underwater to drown it. It must then get back above water to swallow it -- otherwise, the alligator's stomach and lungs would fill with water. Using its incredibly powerful jaws (which are able to exert up to 2,000 PSI), an alligator will break bones or crush shells (in the case of turtles) to create a chunk of flesh that can fit down its throat. Then it will raise its head, open the palatal valve and swallow the piece whole. An alligator can digest anything it swallows -- muscle, bone, cartilage, etc. are all digested completely.
Alligators, being cold-blooded, do not have to eat very often. Once a week is a typical feeding schedule for alligators living in the wild. Excess calories are stored in fat deposits at the base of the alligator's tail. Incredibly, by burning fat reserves, it is possible for an alligator to last more than two years between feedings.
Alligators were nearly hunted to extinction in the 1950s and 1960s. Once they were protected from hunting, however, they were able to recover quickly because of their unique breeding behaviors.
Alligators breed in the spring. The female then builds a nest of mud and vegetation that is about three feet (1 meter) high and 6 feet (2 meters) in diameter. She lays 30 to 50 eggs and buries them in the rotting vegetation. The eggs are white, hard and slightly bigger than a large chicken egg.
The nest provides heat -- it is like a big compost pile and heats up naturally because of the decomposing vegetation. The alligator eggs respond to the temperature. If the temperature is in the low 80s F, the hatchlings will be female. If the temperature is in the low 90s F, they are male. For temperatures in between, the resulting hatchlings are mixture of males and females.
The mother protects the nest from predators, such as racoons, while the eggs are incubating. When the eggs hatch about 40 days later, the hatchlings make a noise and the mother digs them out of the nest. The hatchlings and mother will stay near the nest, and the mother will protect the hatchlings if they get into trouble and cry out. This protective behavior is very rare in modern reptiles, but it is thought to be common in certain dinosaur species.
When it gets cold in the winter, alligators slow down. Below 70 degrees F or so they stop feeding, and when it gets much colder, alligators dig out a den in the bank of a pond or river and go dormant until it warms up again.
Alligators can even survive freezing conditions. They have been known to rise to the surface if the water is about to freeze, with their nostrils above the surface. This allows them to breathe through the ice as it forms. In extreme cases, they get frozen into the surface of the pond for several days and then swim free when the ice melts. See this page for details.
For more information on alligators, other crocodilians and related topics, check out the links on the following page.
Crocodiles and alligators are both green, scaly and toothy — but there's more to them than that. Prove you can spot the differences at HowStuffWorks.
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More Great Links
- American Alligators
- American alligator
- American Alligator fact sheet
- Alligator adventures: Alligators
- Alligators as pets
- Alligator encounter
- Alligator mississippiensis
- Encarta: Alligators
- Integumentary Sense Organs
- Crocodilians - Natural History & Conservation -- includes alligator calls sound files and the Crocodilian species list
- Pallatal valve
- Crocs and metabolism