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 What are crocodilians?

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PostSubject: What are crocodilians?   Fri Jan 11, 2008 1:00 pm

Crocodiles, alligators, caiman, false gharials and gharials make up the crocodilian group, which has survived for about 200 million years. There are three families included in the crocodilians:

Alligatoridae: the American and Chinese alligators, South American caimans; 7 species
Crocodylidae: crocodiles and the false gharial; 14 species
Gavialidae: the gharial; 1 species which is the Indian Gharial

Where do crocodilians live?

They are widely distributed throughout the tropical and subtropical regions of Africa, India, South-east Asia, Australia, North, Central and South America. They are found in habitats such as swamps, ponds, rivers, lakes and marshes.

What is the difference between a crocodile and an alligator?

The main difference is in the shape of the heads. Alligators have broad, rounded snouts whereas crocodiles have more narrow snouts that taper to a point. The other difference is with their teeth. Alligators have a wider upper jaw than lower jaw so when their mouth is closed the teeth in the lower jaw are almost completely hidden and fit into sockets of the upper jaw. In crocodiles, the upper and lower jaw are the same width and so teeth in the lower jaw fit outside when the mouth is closed. This makes them look like they have interlocking teeth. Another difference is the skin of a crocodile which is covered in sensory pits, whereas alligators only have these pits near their jaws.

Are crocodiles more dangerous than alligators?

Some crocodiles are more aggressive than alligators. There are probably more incidents of humans being attacked by crocodiles than alligators because there are more crocodiles in existence.
What do crocodiles and alligators eat?
Their diet is diverse. They prey on anything from dragonflies and bats to sharks, antelopes and even buffalo. Although attacks on humans have occurred, most species of crocodilian don't include humans as a food source. In fact, it has been suggested that a person bending down over a water source may resemble an antelope in the eyes of a crocodile and this is why the attacks occur. The species that habitually hunt humans are the Nile and Indo-Pacific crocodiles. The American crocodile, black caiman and the Indian mugger will on occasion kill humans for food or to defend their nests or territories.


Why don't crocodiles and alligators eat very often?

Crocodilians are extremely energy efficient. They are poikilotherms (cold-blooded), and so depend on external heat sources to regulate their body temperature. Because of this, they do not have to heat themselves using energy fueled by food as humans and other mammals do. Usually crocodilians need only eat once a week or less to maintain their energy levels.

Why do alligators and crocodiles often sit with their mouths open?

This behaviour is called gaping and it is done when the crocodile or alligator is basking in the sun. It is thought that this may act in cooling the crocodile, however, since they also do this during rain and at night it could suggest that gaping has a social function as well.


How are they adapted to an aquatic environment?

Crocodilians are well adapted to water, as well as land. They are excellent swimmers and can hold their posture in water. When submerging underwater they close their ear and nostril flaps. When feeding underwater the back of the tongue acts as a valve to stop water from going into their lungs. Crocodiles and alligators can dive for long periods of time due to their slow metabolic rate. Vibration sensors and touch receptors help them to feel movements of prey in the water. They have a third eyelid, called the nictitating membrane that protects their eyes underwater.


Why are many species of crocodilian endangered?

Some species are endangered due to habitat destruction such as the Nile crocodile whose nesting areas along the river are disrupted by boat traffic. Nearly all crocodilians live in the rainforests and wetlands of developing countries which are being destroyed by logging, development and other industries. Poaching also lowers the crocodilian population. A multi-million dollar business exists in the illegal trade of crocodilian hides. The common caiman is the most hunted crocodile, and makes up 60% - 80% of skins in the trade. However, their bony hides only receive a tenth of the price that is paid for alligator or crocodile skins. The American alligator was one of the first animals to receive protection under the United States Endangered Species Act, they are now no longer endangered but listed as 'threatened' instead. Steps are being taken to alleviate poaching and repopulate species of crocodilians by setting up crocodile farms.

How do crocodiles and alligators catch their prey?

Prey is seized using the element of surprise. Crocodiles sit camouflaged and motionless in the water waiting for prey to come to them. Their eyes and nostrils are high on their head so the rest of their body can be hidden under water. When prey is only a short distance away the crocodile quickly snaps its muscular jaws around the prey and drags it below the water to drown and consume it.


Where do they lay their eggs?

Females lay their eggs in holes they dig in the sand or in large nests made of vegetation and mud. The mother will guard the nest until she hears the cry of her babies, which break their shells with an "egg" tooth. Without the babies call of distress the hatchlings may never see light, since it is the mother who digs them out of the mound of mud. She then picks up her babies in her mouth and carries them to water, breaking the remaining shells and swallowing them. The smallest of the crocodilians may lay 10 to 15 eggs, but larger species like the Indo-Pacific crocodile may lay 50.


Are there any crocodilians at the Aquarium?

The Aquarium houses three caimans that were born in 1978 at Fort Worth, Texas. They were sent here in 1983 from the National Zoological Park in Washington, D.C. The Aquarium is the temporary home for the Golden Crocodiles until April 2000. While these rare and endangered crocs are with us, the caiman will be removed from the exhibit. The Golden Crocodiles, also known as the Indo-Pacific crocodiles, were born in Samutprakan Crocodile Farm in Thailand.


Do crocodilians make good pets?

No. Some people keep baby alligators and crocodiles, but when they grow to over 2 metres long and are difficult to house, they no longer make ideal pets and often have to be put down. They can be dangerous to keep as pets, potentially harming other pets or even people.


How long can they hold their breath underwater?

Usually they can hold their breath from 4 - 15 minutes but can remain underwater for 2 hours if needed and if they aren't stressed. The record time spent underwater is 8 hours in freezing conditions, this is because a colder crocodile uses less energy and oxygen and can hold its breath longer than a warmer one.

Did you know?

Crocodilians:

Shed their teeth regularly. No cavities, no dentists, they have it easy.
Can last months without feeding as long as their body temperature remains low.
Roar like lions. They also snort, jaw snap and tail slap to establish courtships, dominance, territory, and aggression. Crocodiles and alligators also communicate visually through body language and with sub-audible vibrations which are transmitted to animals both in the water and on the surface. These vibrations are created by contracting their trunk muscles.
Are only distantly related to the dinosaurs, while birds are the closest living relative to dinosaurs.
When the American alligator's swamp freezes over most of the reptiles will survive by maintaining a hole through the ice in which to breath.
Mothers respond to the distress call of juveniles and defend them against predators.
Are the only reptile to have a four-chambered heart (all other reptiles have a three-chambered heart).
Have a muscular gizzard similar to birds - which is used to grind up food prior to entering the stomach.
Incubation temperature will determine what sex the juvenile will be.

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PostSubject: Re: What are crocodilians?   Sat Jan 12, 2008 10:39 pm

That was all very good information. More of the same came be found on my site under the link for "Charts", at the bottom of the page.

I am, however, going to argue two points with you. If you add your numbers up, the total crocodilians you come up with equal 22. In reality there are 23 crocodilian species. I'm not sure which one you're missing, but if you let me know which ones you counted, I can prolly fill in the missing man. (Unless you got the info from a "source", in which case, don't listen to him so much!).

Second is that although the big difference between crocs and gators are the snout and teeth; and caiman are considered part of the gatr family; caiiman have longer, pointier snouts, like crocs and some even have teeth that protrude upward like crocs, so don't count on that when trying to figure out what you got.

I have some pictures below of caiman and crocs and gators to show you what I mean.

gator - broad snout - teeth from top:




croc - pointier snout - teeth protrude from top and bottom:



caiman - pointy snout - teeth protrude from top and bottom:






(Bottom three pictures are some of my caiman)
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PostSubject: Re: What are crocodilians?   Sat Jan 12, 2008 11:56 pm

Thanks Bam, I got the above info from a zoo's site I was looking through as my knowledge is poor in this field. But i knew you would put the facts right, which is what i was looking for. :)

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PostSubject: Re: What are crocodilians?   Sun Jan 13, 2008 12:55 am

Any chance you would educate us all, across the pond, on the varying species and how they differ Bam please? I know many will find it very interesting.

My only experience with caiman was only to veiw a 2ft caiman in a 3ft by 18inches by 18 inches fish tank in a crappy shop not far from me. Of course I did report this, but f*ck all was done by it. But i am not getting into the crappy shop arguement as it creates alot of tension and tears. But I will always be on the animals side regardless of what animal it is. Twisted Evil So as you can imagine here across the pond we get little opportunity to learn more about crocodilians, so from a hands on experienced guy it would be appreciated. Very Happy

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PostSubject: Re: What are crocodilians?   Sun Jan 13, 2008 4:05 am

Don't wanna steal your thunder, but after dinner or tonight I'll try and come up with something.
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PostSubject: Re: What are crocodilians?   Sun Jan 13, 2008 11:49 am

Steal me thunder? lol! Your the expert

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PostSubject: Re: What are crocodilians?   Sun Jan 13, 2008 5:19 pm

Reptile Rescue Den wrote:
Steal me thunder? lol! Your the expert

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PostSubject: Re: What are crocodilians?   Sun Jan 13, 2008 5:55 pm

lol!

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PostSubject: Re: What are crocodilians?   Sun Jan 13, 2008 6:28 pm

she aint the boss i am lololol

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PostSubject: Re: What are crocodilians?   Sun Jan 13, 2008 6:32 pm

squaddie79 wrote:
she aint the boss i am lololol
Very Happy

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PostSubject: Re: What are crocodilians?   Sun Jan 13, 2008 8:06 pm

lol!
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PostSubject: Re: What are crocodilians?   Sun Jan 13, 2008 8:19 pm

I'm gonna go to a different thread!
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PostSubject: Re: What are crocodilians?   Thu Jul 17, 2008 10:11 pm

Sorry for dragging up an old thread.
Caimenhunter, would you mind if I use that info on a display here?
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PostSubject: Re: What are crocodilians?   Thu Jul 17, 2008 11:59 pm

Martin S wrote:
Sorry for dragging up an old thread.
Caimenhunter, would you mind if I use that info on a display here?

As long as you were able to note where it came from and who authored it.
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PostSubject: Re: What are crocodilians?   Fri Jul 18, 2008 1:57 am

CROCODILE, in a restricted sense, any reptile of the genus Crocodilus, of which 12 living species occur in warm regions of the world, or of two allied African genera, Osteolaemus and Osteoblepharon, having a single species each; members of these 14 species are true crocodiles as distinguished from the alligators. Broadly, however, the term crocodile is used to denote any member of the order Crocodilia, or Loricata, which includes, in addition to the 14 species of true crocodiles, two gavials, one each in India and Malaysia; two alligators, one each in China and in the United States; and seven caymans, all found in Central and South America.

The true crocodiles, having sharply tapering heads, expose the fourth tooth on either side of the lower jaw in a notch on the outside of the upper jaw. The broad-headed alligators and caymans have the fourth tooth concealed in a matching socket in the overhanging upper jaw.

The alligator is distinguished from the gavial and crocodile by the teeth of the upper jaw, which overlap those of the lower jaw markedly. The gavials are fish feeders exclusively and are easily distinguished from others by their long narrow snouts, which offer little resistance to the water when swung sidewise to catch fish.

The caymans of Central and South America are much like the alligators, but they lack a bony septum in the nose. Crocodilians are survivors of a group that flourished with the dinosaurs and once included specimens over 50 feet (15 meters) long. Its earliest members date from the lower Jurassic. They appear, from the fossil record, to have been most numerous in Europe and North America until quite recent times.

In the Pleistocene, crocodilians have been found in India and Africa, as well as in Europe and North America. Crocodilians are among the largest living reptiles, but specimens are seldom as large as those described in print. The American crocodile, C. acutus; the Orinoco crocodile, C. intermedius; and the marine crocodile, C. porosus, found in the Australo-Malay Archipelago, all reach about 23 feet (7 meters). The last named is reported to reach lengths of more than 30 feet (9 meters), but such reports are probably exaggerations or miscalculations. The Cuban crocodile, C. rhombifer, a rare species found only in Cuba, reaches a length of 12 feet (3.6 meters). The smallest crocodilians are the Chinese alligator, Alligator sinensis, which attains a length of about 5 feet (1.5 meters), and one of the South American caymans, Caiman palpebrosus, which seldom reaches a length of 4 feet (120 cm). Most crocodilians live most of the time in the water, where they frequently float lazily with only the nostrils, eyes, and ears, which are raised above the general level of the head, projecting above the surface. At such times a fleshy valve in the rear of the mouth prevents water from entering the air passages, and an internal passage in the skull conducts air from the projecting nostrils to the throat. The powerful, vertically flattened tail and webbed feet facilitate swimming, but only the marine crocodile ventures far from land. Crocodilians come ashore to build their nests and to lay their eggs, and sometimes to bask in the sun, lying agape to dry out the leeches that infest their mouths; when disturbed they run into the water with a speed that is surprising in view of the tremendous girth of large specimens. The eggs, laid in a pile of decaying vegetation or in holes in the sand, are ellipsoidal in shape, and their shells are leathery. The young, on hatching, grow rapidly. In captivity the young of the American alligator are about 18 inches (45 cm) long at the end of the first year, and at about the third year they are roughly 3 feet (90 cm) long. The age of crocodilians has always been exaggerated; the animals look old at birth, and this fact has led to much fanciful speculation. Large specimens of any species may be assumed to be in their thirties; exceptionally large individuals, in their forties. Zoo specimens have lived 25 years, and one American alligator survived 56 years. Any large crocodilian, either on shore or in the water, may prove dangerous to man. This reptile does not attack indiscriminately, but it is fast. Its tail is flexible and powerful, and on land it can run well in a straight line. Its characteristic attack is a slow, careless approach terminating in a sudden rush. When its jaws are set in a large animal it rotates or spins on its long axis, thus tearing its mouthful of flesh out of the larger body. It sinks large animals in the water, eating the flesh when it begins to decompose. In nature, full grown specimens have no enemies but man. The young, however, are preyed upon by many large birds, mammals, and fishes. Economically, crocodilians are definitely valuable, particularly for their hides, which have been widely used for shoes, bags, belts, and other purposes. This value has led to their extermination in many areas, with the result that most nations now protect their crocodiles. Furthermore, in some states of the United States, notably New York the sale of crocodilian products is forbidden.


See also ALLIGATOR; CAIMAN, GAVIAL; REPTILES. ROBERT STUART MATHEWS



http://www.crocodile.org/lord/crocodile.html

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PostSubject: Re: What are crocodilians?   Fri Jul 18, 2008 3:58 am

You guys really need to ignore the above post. It was written in 1996. There have been numerous changes to the beliefs and listings and cladagrams of crocodilian since that time.

There are spelling errors in the original and the c&p which makes me believe the writer was more interested in proving he could post than what the facts were. The number of sub-species has been rethought and changed.

The lengths of the adults is completely wrong, as is the growth rate.

And there are other glaring mistakes.

If anyone has any questions, I'd be happy to answer them if I can, but taking info from c&p stuff that came from out of date sites is not really going to do you any good.
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