The order Crocodilia includes crocodiles, alligators, caimans, and other large, predatory, semi-aquatic reptiles. All 23 of the species in this order have long snouts and powerful bites, non-overlapping scales, and good swimming abilities.
There are three families within the Crocodilia order. Gavialidae is the family of gharials, which are rare, narrowed-snouted crocodilians only found in Southeast Asia, pictured below.
Corcodylidae is the family of crocodiles and includes 12 species.
Alligatoridae is the family of 2 alligators and 6 caimans.
So how do you tell the difference between them all? Alligators and caimans generally only live in freshwater, while crocodiles tend to live in saltier waters because they have better developed salt glands that allow them to expel saline. Crocodiles have long pointed 'V'-shaped snouts, while alligatoridae species tend to have shorter 'U'-shaped snouts. The broader alligator jaw is stronger and can crack hard objects like turtle shells, while the crocodile's jaw is more suited to a variety of prey.
The crocodile's upper and lower jaws are almost the same size, so when they close their mouths the upper and lower teeth are visible outside the mouth. They also have a larger fourth tooth that sticks out. In alligators and caimans, you cannot see the bottom teeth or prominent fourth tooth jutting out.
Both alligator and crocodile species have dermal pressure receptors that look like small pits in the skin and can help them track prey by sensing small pressure changes in water. Crocodiles are covered in these receptors pits, while alligators only have them on their jaws.
Okay, so that's how you tell crocodiles from alligators and caimans. But how do you tell alligators from caimans? I always thought that caimans were much smaller than alligators. But that's not true! Certain caimans are small, with the spectacled caiman of Central and South America only reaching 2.2m on average. But the jacare, or black, caiman from the Amazon and Pantanal can grow to a whopping 5m, putting the American alligator's 4.25m to shame.
The real difference between these two subfamilies lie in the snout. Caimans lack bony septums between their nostrils. Instead they have bony scutes (or scales) that protect the nostrils.
I also thought caimans were less aggressive and dangerous than alligators. But it turns out caimans tend to be more agile than the alligator and more similar to the aggressive crocodile in their behavior. They also have longer, sharper teeth than the alligator. So if you are like me and took comfort in the fact that the Pantanal only has caimans, not alligators, think again! Because this lesser known crocodilian packs a punch...or should I say, a bite!
Sources:
Alligators and Crocodiles: Animal Planet, http://animal.discovery.com/reptiles/alligator-vs-crocodile1.htm.
Crocodilia, Wikipedia, http://en.wikipedia.org/wiki/Crocodilia#Evolution_and_classification.
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| From top to bottom, a gharial, caiman, alligator, and crocodile. Source http://24.media.tumblr.com/tumblr_m86s0rnKbj1qecsulo1_1280.jpg |
There are three families within the Crocodilia order. Gavialidae is the family of gharials, which are rare, narrowed-snouted crocodilians only found in Southeast Asia, pictured below.
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| Gharial. Source: http://www.perlgurl.org/archives/images/IMG_3353_z38X.JPG |
Corcodylidae is the family of crocodiles and includes 12 species.
Alligatoridae is the family of 2 alligators and 6 caimans.
So how do you tell the difference between them all? Alligators and caimans generally only live in freshwater, while crocodiles tend to live in saltier waters because they have better developed salt glands that allow them to expel saline. Crocodiles have long pointed 'V'-shaped snouts, while alligatoridae species tend to have shorter 'U'-shaped snouts. The broader alligator jaw is stronger and can crack hard objects like turtle shells, while the crocodile's jaw is more suited to a variety of prey.
Top, crocodile. Bottom, alligator. Source: http://images.nationalgeographic.com/wpf/media-live/photos/000/002/cache/american-crocodile_219_600x450.jpg; http://www.animalpicturesdaily.com/wp-content/uploads/2013/04/Florida-alligator-1024x796.jpg
The crocodile's upper and lower jaws are almost the same size, so when they close their mouths the upper and lower teeth are visible outside the mouth. They also have a larger fourth tooth that sticks out. In alligators and caimans, you cannot see the bottom teeth or prominent fourth tooth jutting out.
Both alligator and crocodile species have dermal pressure receptors that look like small pits in the skin and can help them track prey by sensing small pressure changes in water. Crocodiles are covered in these receptors pits, while alligators only have them on their jaws.
Okay, so that's how you tell crocodiles from alligators and caimans. But how do you tell alligators from caimans? I always thought that caimans were much smaller than alligators. But that's not true! Certain caimans are small, with the spectacled caiman of Central and South America only reaching 2.2m on average. But the jacare, or black, caiman from the Amazon and Pantanal can grow to a whopping 5m, putting the American alligator's 4.25m to shame.
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| Jacare caiman. Source: http://upload.wikimedia.org/wikipedia/commons/e/e4/Caiman_yacare_head.jpg |
I also thought caimans were less aggressive and dangerous than alligators. But it turns out caimans tend to be more agile than the alligator and more similar to the aggressive crocodile in their behavior. They also have longer, sharper teeth than the alligator. So if you are like me and took comfort in the fact that the Pantanal only has caimans, not alligators, think again! Because this lesser known crocodilian packs a punch...or should I say, a bite!
Sources:
Alligators and Crocodiles: Animal Planet, http://animal.discovery.com/reptiles/alligator-vs-crocodile1.htm.
Crocodilia, Wikipedia, http://en.wikipedia.org/wiki/Crocodilia#Evolution_and_classification.
Wow those are some crazy looking crocodilians. I hear caimans are super common but I wonder if we will see any larger crocodilians while we are there, preferably from a comfortable distance.
ReplyDeleteThanks for this post- I have always wondered about the differences between members of the crocodile family, and this really clarifies it. I had never heard of caimans before this class, so it's interesting to know about their relation to the better-known representatives of the order Crocodilia as well as their similar physical features. I'm looking forward to seeing them in the Pantanal!
ReplyDeleteThanks Morgan for the clarification. As someone who was rather "indoorsy" coming into college, I definitely did not know much about the differences between these animals. Hopefully we'll be able to identify the different species in the Pantanal!
ReplyDelete