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Neat to know ~ Creature of the week

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American Crocodile, Florida, USA

Photo: Judd Patterson, Public Domain

Saltwater Crocodile, Northern Australia

Photo: fvanrenterghem, CC BY-SA 2.0



If you ever want to catch a glimpse of a life form from the distant past, take a look at the crocodile.  This evolutionary success story started some 200 million years ago, with the earliest ancestor of today’s crocodile.  Still thriving in many parts of the world today, this resilient reptile has been around relatively unchanged for 80 million years.  While dinosaurs died off 65 million years ago, the adaptability of the crocodile has allowed it to survive as the most dominant of the reptiles and one of the most successful predators on Earth.

What has made the crocodile so invincible through the ages?  First of all, it is at the top of the food chain and no higher predator threatens it.  (Only human activity jeopardizes its survival, as you will read later.)  Also, it is built to hunt.  A crocodile’s speed and agility, on both land and water, combined with jaws so strong that they can pulverize bone in minutes, make it an unstoppable hunting machine.  Finally, its defenses are highly evolved.  It is shielded on the outside by a tough, scaly hide and on the inside by a rugged immune system. 

Read on to find out more about this relic of the past that is showing no signs of slowing down.

It’s got a lot going for it!

– Crocodiles have powerful tails that let them maneuver quickly and efficiently in water.  And thanks to their uniquely adapted hearts, they can stay underwater for up to an hour.  In addition, their eyes, nostrils and ears are on the tops of their heads.  This allows them to stealthily stalk prey while remaining submerged and virtually unseen.

– Crocodiles can run swiftly on land (but not for long).

– Because crocodiles have superior night vision, they do a lot of their hunting in the dark when their less keen-sighted prey are at an even bigger disadvantage than usual.

– Can strong also be sensitive?  In the case of crocodiles, the answer is yes.  Their immense jaws are able to pick up more stimuli than your fingertips!  When a crocodile is sitting still in unmoving water, it can sense ripples coming from an animal drinking 20 meters (21 yards) away.

– A crocodile’s mighty jaws are the most powerful in the animal kingdom.  In a matter of milliseconds, they can snap shut with over 2,000 kilograms (4,409 pounds) of force.

– Like all reptiles, crocodiles are cold-blooded.  A more accurate term is “ectothermic” (“ecto” = outer or outside; “therm” = heat).  Unlike mammals and birds, which are warm-blooded, or “endothermic” (“endo” = inner or inside), crocodiles rely on their environment to regulate body temperature, rather than maintaining it themselves.  If they are cold, they will seek sunny areas; to keep from overheating, they take shelter in the shade.  So, unlike us endotherms, they are able to conserve a lot of the energy that they get from the food they eat, since they don’t need to use it up to manage their internal temperature.  A big, mature crocodile can live for a year without eating!

– Despite this, most crocodiles eat about once a week.  And this brings us to another reason these predators are so resilient: they eat just about anything, from fish to birds to mammals, large and small.  They will even eat the remains of dead animals.  Crocodile stomachs contain extremely acidic gastric fluids, which means they are able to consume just about every part of an animal, including bones, horns, hooves, and shells.

– The average lifespan of a crocodile is 30-50 years.

Brainy Crocs

– Crocodiles have the most complex social relationships in the world of reptiles.  They tend to be loners.  But when it comes to hunting and nurturing their young, they work together.  They form long-lasting bonds and communicate using not only their voices, but also body positions and physical contact.

– Crocodiles have keen senses.  Their smell receptors, as well as their hearing, are more advanced than those of any other reptile.  Crocodiles are quick learners, too.  Once they encounter a dangerous situation, they remember it and know how to avoid it in the future.

Crocodiles vs. Alligators

– Despite the fact that they are both from the same scientific order –  “Crocodylia” – crocodiles and alligators are from different families within that order.  Alligators are in the Alligatordae family, and crocodiles are in the Crocodylidae family.

– How can you tell a croc from a gator?  Maybe the most easy-to-spot difference is in the shape of their snouts.  Crocodile snouts are narrow and shaped like long triangles.  Their teeth are more exposed, too, making them look a bit like they are smiling with all their teeth.  Alligators, on the other hand, have wider, less pointy snouts.  Their teeth aren’t as visible. 

– Crocodiles are bigger than alligators.  Adult gators are 10 – 15 feet (3 – 4.5 meters) long and around 500 pounds (227 kg), while adult crocs are between 14 and 17 feet (4.3 – 5 meters) long, weighing up to 2,200 pounds (998 kg).

– Alligators tend to be darker in color than crocodiles.

– Crocodiles have adapted to living in saltwater.  They have special glands in their tongues that expel the extra salt.  Alligators have the same glands as crocodiles, so they can tolerate brackish water (a combination of saltwater and freshwater), but they prefer freshwater because their salt-excreting glands aren’t as developed as those in crocodiles.

– Alligators are faster on land than crocodiles (but neither is as quick and deft on land as in water).  Alligators can run up to 11 miles per hour (18 km per hour), while the top speed of crocodiles is around 9 mph (14 kph).

– Alligators are shyer than crocodiles and far less likely to attack a human.  In contrast, crocodiles can frequently be aggressive and have been known to attack for no apparent reason.

– Alligators are found in the southern United States and in China.  Crocodiles can be found in both North and South America, as well as in Africa, Australia, and Asia.  The only place where alligators and crocodiles are found together is in the Florida Everglades.  In the U.S., the more than 3 million alligators far outnumber the less than 2,000 crocs.

– The American alligator was previously endangered.  But it has made a strong comeback, thanks in large part to protective measures put in place by state and federal agencies.  In contrast, the smaller Chinese alligator is critically endangered.  Certain species of crocodile are also endangered, including the Philipine, Cuban, and slender-snouted crocodile.  Much of the problem comes from habitat loss and hunting.

Sources: Everglades Holiday Park, “Alligators vs. Crocodiles,” https://www.evergladesholidaypark.com/alligators-and-crocodiles/, February 2020; Goodman, Paul, Owlcation, “The 8 Main Differences Between Alligators and Crocodiles,” https://owlcation.com/stem/Whats-the-difference-between-alligators-and-crocodiles, February 20, 2021; National Geographic, “American Alligator,” https://www.nationalgeographic.com/american-alligatorBritannica, “Alligator,” https://www.britannica.com/animal/alligatorBBC, “The Wonder of Animals – Crocodiles,” https://www.bbc.co.uk/crocodiles; PBS.org, “Crocodile Secrets of Survival,” https://www.pbs.org/crocodile-secrets-of-survival/, September 15, 2011.