When you think of an alligator or crocodile some specific images might come to mind. One of them is an alligator crocodile, lying motionless on the bank of a river, with their mouth open and basking in the sun.
It seems counterintuitive that these top-tier predators spend time lying around in the sun. Don’t they have anything more productive to do?
Why do alligators and crocodiles bask in the sun?
The main reason that alligators and crocodiles bask in the sun is to thermoregulate. These reptiles are ectothermic and rely on outside sources of heat to warm their bodies. On sunny days alligators and crocodiles can warm up and boost their metabolism just by lying out and under the sun. Â
This article will explain the difference between ectothermic and endothermic animals, and how it relates to why reptiles bask in the sun. We’ll also talk about whether or not crocodiles and alligators need sunlight and what other tactics they might use to thermoregulate.
Ectothermic vs. Endothermic Animals
By definition, an endothermic or warm-blooded animal is an animal that uses its own energy to stay warm. Endothermic animals are usually mammals and birds, but some fish are surprisingly also warm-blooded.
These animals, shiver, sweat, and pant to keep their body in homeostasis. Air temperatures can’t fluctuate very much or their bodies will go into shock. Being warm-blooded definitely has its pros and cons.
Ectothermic or cold-blooded animals are animals that have to rely on external sources of heat to stay in homeostasis. Because ectotherms can’t regulate their temperature internally they need to move around often to find the right external environment.
Some examples of cold blooded animals are vertebrates like fish, amphibians, also reptiles, in addition to invertebrates. Ectotherms generally have lower energy requirements than endotherms because they source their energy from the outside world not internally.
Alligators and crocodiles are ectothermic and need to rely on outside factors to change their body temperature and metabolism.
Why Do Alligators And Crocodiles Bask In The Sun?
Basking or sunning is a thermoregulatory behavior that both endothermic and exothermic animals used to stay warm. Even ask humans like to lay out in the sun and warm up from time to time.
It’s a pretty simple explanation for why alligators and crocodiles bask in the sun. They’re just looking to warm up a little throughout the day. Crocs and gators have a preferred body temperature of 30 to 33°C. To achieve this temperature, they’ll often need to warm up at some point throughout the day.
They’ll use the middle of the day to warm up as they lay in the sunlight. Being warm boosts a reptile’s metabolism, and helps them to move more quickly. As ectotherms, these animals usually become cold and slow-moving in the evenings.
You can see a great example of an alligator basking in the sunlight in the video below.
And don’t worry, if it gets too hot during the day, alligators and crocodiles, have a solution for that as well. They’ll cool down by digging a hole and taking a nap in the darkness.
Do Alligators And Crocodiles Need Sunlight?
Just like any other diurnal reptile, alligators, and crocodiles need sunlight to survive.
As reptiles spend time basking in the sun, they absorb UV rays. These rays are so important to help the body synthesize vitamin D3. Why is vitamin D3 important? Vitamin D3 allows for the proper absorption and use of calcium. As we know, without calcium, animals become weak and can fall prey to metabolic bone disease.
While some nocturnal reptiles do not need sunlight to thrive, alligators, and crocodiles, absolutely do.
What Other Methods Do Alligators And Crocodiles Use To Thermoregulate?
Since alligators and crocodiles are active thermic, you’re probably wondering what other methods they use to control their body temperatures besides sunning. Here are some of the most common ways alligators and crocodiles can cool off or warm up as needed.
They’ll Relocate
What is the easiest way for an ectothermic animal to thermoregulate is to relocate.
Basking in the sun is one way to help an animal warm up. But, if an alligator or a crocodile is too warm, they can simply relocate to a shady or wet area. Alligators and crocodiles can even move to rest underwater if they’re truly overheating.
Relocating is a common technique for all reptiles in thermoregulation. It’s one of the reasons why you need to provide your pet reptiles with a thermal gradient in their enclosures. Thermal gradients allow animals to choose whether they need to warm up or cool down depending on their internal temperature.
Open Mouth Breathing
Alligators and crocodiles are well known for sitting with their mouths open. There are a few reasons for this behavior, but one of them has to do with thermoregulation.
When alligators and crocodiles bask in the sun, their temperature naturally rises. If they get too warm they will want to cool down in place. Just like in dogs, panting can drastically lower internal body temperature through evaporation. Basically, saliva evaporates off of the large surface area of the tongue and effectively cools the body.
Obviously, if alligators and crocodiles get too hot open mouth breathing won’t keep them cool enough. They’ll have to turn to other methods, or just move into the shade.
Osteoderms
An osteoderm is basically a skin and bone deposit. Osteoderms are found on reptile scales and spikes. Because osteoderms are highly vascularized tissue, it’s believed that alligators and crocodiles can use these areas of their body to absorb or expel heat much faster than normal.
A study showed that scales with osteoderms showed small differences in temperature profile as compared to nearby scales without osteoderms.
Gator Holes
Alligator holes are another way that these large reptiles thermoregulate.
In the warm season, alligators will often dig holes in order to stay cool. They’ll lay in the cool wet ground, and their temperatures will drop. Later holes, stay cool because they often fill with water.
Not only are gator holes helpful for keeping alligators cool but they’re also an essential part of the eco-scape of the Everglades.
Final Thoughts
There is a good reason why alligators and crocodiles bask in the sun. It’s really a very similar reason as to why all other animals like to bask in the sun. The sunlight helps to warm them up.
For ectothermic animals harnessing this external source of energy is especially important. The sunlight can help them, maintain an ideal body temperature, and stay comfortable throughout the day.
