Do you ever stress about sleeping and feel that you have half of your brain awake and half asleep? While humans have both hemispheres of their brain working together while they are in REM sleep, this is not the case for crocodiles. Scientists studying the sleeping patterns of crocodiles have found that they sleep with one eye open to monitor potential threats. Only one half of their brain may shut down while sleeping. A study of Australian crocodiles found that they would monitor a human in the room while sleeping and continue to look at the same spot even after the human had left (1). So while you may feel that you are unable to turn off your brain while sleeping worrying about potential monsters under the bed, crocodiles certainly don’t turn theirs off so they can evaluate danger.
Large Crocs
The largest crocodile living today is one named “Cassius Clay” who measures over 17 feet long and is a 100-year-old croc living in Australia. Going back in time, Deinosuchus was an ancient crocodile that measured up to 33 feet in length and could have eaten dinosaurs. Their teeth were the size of bananas and have been nicknamed “terror crocodiles” roaming the earth between 75-82 million years ago (2). Further back (around 112 million years ago) lived the Sarcosuchus (aka flesh crocodile) which was as long as 40 feet which means it was even longer than a T-Rex (3).
Differences between a crocodile and alligator
The primary difference between the crocodile and alligator is the shape of their snout. Other distinguishing features between the two are listed in the table below (3).
| Crocodile | Alligator | |
| Snout | V-shaped | U-shaped |
| Size | 14-17 feet | 10-15 feet |
| Teeth | Seen outside of mouth when jaw shut | Concealed inside of mouth when jaw shut |
| Water habitat | Saltwater | Freshwater |
Habitat and Eating Habits
There are 23 species of crocodiles throughout the world. In the United States, the American crocodile can be found in the salt waters of Florida in mangroves and swamps. The crocodile is a carnivore and will munch on fish, shellfish, and birds. As a nocturnal animal, they will hunt at night and often lay very still near the water’s edge to capture an animal drinking water which it will then bring back into the water and drown it.
The reproductive life cycle of a crocodile
- Females lay up to 48 eggs in a nest that is either dug up in a mound or hole, depending on the species of crocodile.
- Eggs incubate for 55-100 days. The temperature during incubation can play a role in the sex of a crocodile – cooler temperatures can produce more females, warmer temperatures more males.
- When the baby reptiles hatch, they will need help from their mothers to get out of their eggs and then to the water, which she will often carry them in her mouth (5).
Fun crocodile facts (4, 5, 6)
- Run up to 11 MPH on land
- Can weigh up to 2,200 pounds
- Roar to attract mates
- Can swim up to 900 km
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References
- Webb, Jonathan. Crocodiles sleep with one eye watching. BBC (2015). Retrieved from https://www.bbc.com/news/science-environment-34572433
- Saldivia, Gabriela. ‘Teeth The Size Of Bananas’; New Study Paints Picture Of ‘Terror Crocodiles.’ NPR (2020). Retrieved from https://www.npr.org/2020/08/12/901520688/teeth-the-size-of-bananas-new-study-paints-picture-of-terror-crocodiles
- Millward, Adam. An introduction to the biggest crocodile ever that makes today’s crocs look tiny. Guinness World Records (2019). Retrieved from https://www.guinnessworldrecords.com/news/book/2019/7/an-introduction-to-the-biggest-crocodile-ever-that-makes-todays-crocs-look-ti-584595.
- What’s the difference between alligators and crocodiles? Everglades Holiday Park (2020). Retrieved from https://www.evergladesholidaypark.com/alligators-and-crocodiles/.
- Ross, James. Crocodile. Britannica (2020). Retrieved from https://www.britannica.com/animal/crocodile-order/Locomotion#ref38422.
- Saltwater crocodile guide: diet and where they live in the wild. Discover Wildlife (2020). Retrieved from https://www.discoverwildlife.com/animal-facts/reptiles/facts-about-saltwater-crocodile/