An up close shot of a baby alligator. Image taken at the San Francisco Zoo.
It’s hard to believe I’ve been writing this blog for so long and yet I haven’t written about alligators until today. There are so many cool and amazing things about alligators, a lot of which are adaptations that are so efficient, they have been around in some form for millions of years.
Take the little dots all over their face, which you can see on Lafayette, the alligator shown above. Those little dots can feel vibrations in the water. Obviously this can help them find moving food. But it may also play a role in courtship. When alligators are courting, the males will make a low bellowing sound and blow bubbles and the vibrations these actions make in the water can be felt by other alligators. When they’re courting, they’ll also rub each others backs. Here is a great video of alligators making their bellowing sounds. I know is sounds really ferocious, but this is not the sound to worry about. When an alligator is feeling threatened (and therefore can be dangerous, although very few people are attacked and killed by alligators), they make a hissing sound. Hiss=bad.
I will reiterate, alligators are really not usually aggressive. They are territorial, so you want to leave them their space, but they don’t usually see people as food. We’re too big. It’s crocodiles you gotta watch out for. So…how do you tell the difference? Well, where are you? If you are not in the Southeastern United States or in the Yangtze River in China then you are looking at a crocodile. But if you are in the south east of the U.S., then you can encounter both. Crocodiles are generally going to be much bigger, although a small crocodile and a large alligator will be very close. Crocs will have a narrower snout and at least two of their lower teeth will be visible when their mouth is closed. Alligators have a more rounded snout and their bottom teeth don’t show when their mouth is closed.
Claude, an albino alligator. Notice his "U" shaped snout and the lack of visible bottom teeth. Image taken at the California Academy of Sciences.
Still, my advice is to not get close enough to check out their dentition.
So, humans are not really on the menu for alligators, but as opportunistic carnivores, they will eat just about any appropriate sized meat, including fish, turtles, birds and whatever else they can grab. But, if not eating them for dinner or feeling threatened by them, alligators can sometimes live closely with other animals without any danger. Claude (above) got along quite well with his snapping turtle tank mates. And this baby alligator is enjoying a turtle bed:
Alligator Lafayette using his turtle tank mates as a bed. Image taken at the San Francisco Zoo.
While we’re looking at a baby alligator, their is a lot to be said about how these little cuties come about. As reptiles go, the alligator mom is very attentive to her young. She starts by making a nest for them. She makes a nest out of decaying material and in the decaying process it gives off heat. In a sense she makes a natural incubator. Whether or not a young alligator is hatched a male or a female depends on the temperature (one of the concerns about climate change is that it will skew the ratio of males and females for animals with temperature dependent sex determination) they are incubated at. Since the ones at the center of the nest will typically be warmer than those at the outside, this usually leads to a pretty decent mix of males and females. When the young are ready to hatch, they will start making hatching calls that sound like a video game laser or a chirp. They make these sounds while they are still inside of their egg! The sound lets mom know that it’s time to unbury her nest and carry her little hatchlings to the water very gently in her mouth. She will care for her young for up to 2 years after they are hatched, which is very important since there are many predators for a young alligator, including other alligators. If a young alligator makes a distress call, the females in the area that have young will come to the aid of that youngster, whether it’s their young or not.
Lafayette on his turtle tank mate. Lest you think that the alligator is always on top, I have definitely observed turtles climbing over their alligator tank mates as well. Image taken at the San Francisco Zoo.
This young alligator was not even two years old when this picture was taken. For alligators, that is just a baby. They can live to be 65-80 years old in the care of a zoological facility and even in the wild they are very long lived. And they are survivors. Because they have low energy demands and relatively slow metabolisms they can even go up to 2 years without eating at all, just relying on the stores of fat in their tails. 2 years! These traits plus one other really cool adaptation also gives them the ability to hold their breath in warm water for up to 30 minutes. That other adaptation? Well it’s a little piece of their anatomy that is very special. They breathe and circulate blood pretty much just like we do. They breathe air into their lungs. Blood comes through the lungs to get oxygen and then gets pumped out to the body then back to the lungs, to the body, to the lungs and so on. But their 4 chambered heart (like ours and their relatives the birds but different from other reptiles) has a shunt in it that allows them to bypass their lungs entirely. They can keep recirculating their blood through their body and getting every last bit of oxygen out of it without it going to the lungs to refill. What a cool trick! In fact if you lower the water temperature, because they are cold blooded their metabolism drops even more. The record for an alligator staying under water, albeit in near freezing temperatures was 8 hours! 8 hours without breathing!
Their lungs are no less special than their heart shunt when it comes to assisting them in their aquatic lifestyle. Their lungs, filled with air, provide quite a lot of buoyancy. The alligators use this to their advantage. When they want to dive under the water, they can shift their lungs towards their tail. This lifts their lower regions up and dips their head downwards, giving them the first little dive they need. They can also shift their lungs from side to side, to allow them to roll. If anyone reading this was a fan of the crocodile hunter, you’ll remember him talking about the animal’s “death spiral.” That was achieved by moving their lungs around inside of their chest cavity.
Claude's rock is heated and he enjoys basking on it, especially after a big meal. Image taken at the California Academy of Sciences.
See I told ya. A turtle climbing on an alligator. Image taken at the California Academy of Sciences.
As well adapted as alligators are, there has been just one force of nature that almost proved to be too strong for them. Yup. You know it. Us. Believe it or not, there was a time when alligator skin purses, belts and boots were super fashionable-to the point where alligators were declared “endangered” even before the Endangered Species Act was passed. Fortunately, protections were put in place and alligator farms were established. These farms were allowed to operate as long as they released at least 25% of their alligators into the wild. With all of the protections in place, alligators flourished again and they are doing really well. Although, they certainly still have some human induced problems…the most interesting one being an introduction of non-native ginormous snakes, Burmese pythons, in Florida. Alligators can eat the young of these snakes but the adult snakes can take on alligators. The fascinating part about it is that alligators, when stressed, can lower their metabolism substantially and reduce their heart rate. When a snake is constricting, and the alligator drops its heart rate to just a few beats per minute, the snake assumes it’s dead and begins to swallow it. However, the alligators sometimes seem to come back from the dead and begin to fight the snakes from the inside out! There have actually been instances where the snake finished eating the alligator and it burst open from the inside! You can see a great video of a partially swallowed alligator fighting back here.