Croc Biology and Behavior

Part of the Crocs: Ancient Predators in a Modern World exhibition. 

Shared Traits

In additions to genetic similarities to birds, their closest living relatives, crocs also share several important anatomical and behavioral characteristics. Like birds, these large reptiles have four-chambered hearts and highly efficient one-way lungs. They also build nests and care for their young. 

Take a Big Bite

Large species like this Nile crocodile have among the most powerful bites on the planet.
Image: Wikimedia Commons

When it comes to hefty bites, crocodilians are unmatched. Big crocs produce bite forces that exceed the structural limits of their own teeth and bones—point pressures on the tips of teeth can approach 250,000 pounds per square inch! Powerful muscles in the jaws, head, and neck allow crocs to crunch, twist, and shake their prey violently.

Who Needs A Dentist?

Crocodile teeth are constantly being replaced as they fall out. 
Image: Wikimedia Commons

The cone-shaped teeth of crocodilians are continually replaced as they wear. Beneath each visible tooth is a stack of replacements in various stages of development. When an old tooth is lost, the one under it grows into its place. A croc may go through as many as 3,000 teeth in its life.

Field First Aid

Crocodile fights are common, but factors in their blood help the animals stave off infection.
Image: Wikimedia Commons

Despite being injured by prey and other crocs, crocodiles rarely suffer from infections. This resistance seems to be due in part to proteins in crocodile blood. Lab tests have shown that these molecules provide innate immunity to bacteria, viruses, protists, and fungi.

"Cold-blooded" Crocs

Basking in the sun helps these mugger crocodiles regulate their body temperature.
Image: Wikimedia Commons

Crocs are ectothermic, which means they rely on their surroundings for heat. To regulate their body temperature, these animals move in and out of the Sun, change their postures, and even modify their own blood flow. Since they use the heat of the Sun to stay warm, crocs use energy from food more efficiently and can go without a meal for long spans of time.

Doting Parents

Baby alligators tend to stay close to their mother after hatching.
Image: Wikimedia Commons

Most species of crocodiles are attentive parents who care for their young after they hatch. Females scoop hatchlings into their mouths and carry them into open water. Baby crocs from the same nest usually stay together, under the protection of their mother, for weeks and months after hatching.

Lead image: Although crocs have an ancient history, modern crocodiles are not “living fossils”—they’re modern animals that are elegantly adapted to their environments. (© McDonald Wildlife Photography)