CROCODILES: THEIR HISTORY, CHARACTERISTICS AND BEHAVIOR

CROCODILES


Crocodiles are the largest reptiles. They are also the largest of all predators that spend some time on land. The biggest crocodiles are bigger than the biggest tigers and lions and polar bears. In the water only Great White sharks and Killer Whales are bigger predators..

A big crocodile, according to National Geographic writer Rick Gore, "is cunning enough to stalk a human, strong enough to bring down and dismember a water buffalo, yet gentle enough to crack open its own eggs to release its young." Dr. Daphne Soares, a neuroscientist at the University of Maryland, told the New York Times, “I absolutely love these creatures. They're beautiful, elegant and goofy at the same time...”An alligator looks like nothing so much as a big, amphibious and grievously misunderstood kitten. Sure, it sports thick scales and bulging bony knobs called osteoderms rather than fur, and 80 teeth to the house cat's 30, and a tail.”

Describing why crocodile are not loved like some other animals, Wayne King of the New York Zoological Society said: "They're not cuddly. They don't have big soulful eyes like seals. Most of the animals the world is concerned with are beautiful, or they tug at your heartstrings. Crocodiles have a pretty toothy leer. They eat dogs in Florida---sometimes even people. Who could love them?" [Source: Rick Core, National Geographic, January 1978]

Explaining mankind's fascination with crocodiles and other dangerous animals the eminent biologist E.O. Wilson once wrote: "We're not just afraid of predators, we're transfixed by them, prone to weave stories and fables and chatter endlessly about the them, because fascination creates preparedness and preparedness, survival. In a deeply tribal sense, we love our monsters."

Crocodiles, Alligators, Caiman and Gharials


crocodile dentition

There are 23 species of crocodilians, in three families---crocodiles (13 species), alligators (two species) and caimans (six species) and gharials (two species)---living in 100 tropical and sub-tropical countries. All reside within 4000 kilometers of the equator.

Crocodiles are essentially Old World creatures and alligators and caimans are New World ones. How can you tell them apart? Crocodiles have: 1) relatively narrow snouts; 2) lower teeth that are visible when their mouths are closed; and 3) a special notch on either side of their upper jaw for the forth tooth of the lower jaw. Alligators have a wider, more rounded snout, their lower teeth are not visible and rest inside their upper teeth and mouth and they lack the notch. Gharials can easily be recognized because they have long, very slender snouts.


Crocodiles and History

Crocodiles have been around for 240 million years, appearing 25 million years before the first dinosaurs and 100 million years before the first birds and mammals. Crocodiles that lived 230 millions years ago were up to 40 feet long. "Our primate ancestors were ratty little things that went around stealing eggs," Dr. Perran Ross, a crocodile specialist and professor of wildlife ecology and conservation at the University of Florida, told the New York Times. "Ancestral crocodiles had basically the same body plan we see today, apparently because it works."

Crocodiles are regarded as the closest living relatives of dinosaurs. They have many dinosaur-like features including bird-like arrangements of the hip bones, and teeth that are mounted in sockets rather than being fused directly to the jawbone. Recent taxonomic analysis has reasoned that dinosaurs, crocodiles and birds should be classified in same the branch of animals.


Sarcosuchus, dinosaur-age crocodile

Crocodiles are more closely related to birds than they are to snakes, geckos and other reptiles. Birds and crocodiles, for example, have sophisticated four chambered hearts, while lizards and snakes have only three chambers. A four-chamber heart boosts brain performance and offers more flexibility to changing environments than a three-chamber heart. Crocodiles display a number of bird-like behaviors such as building good nests, and brooding, protecting and fussing over their eggs.

The Egyptians revered crocodiles. Their river god Sobek is modeled after one. Entire crocodiles families were mummified and placed in sacred tombs with gold bracelets placed on their ankles. A Greek historian visiting an Egyptian Crocodileopolis saw priests feed them honey wine and cakes. Winston Churchill was among those who did not look upon crocodiles with the same affection. He once wrote "I avow...an active hatred of these brutes and a desire to kill them."**

Evolution of Crocodiles

Mel White wrote in National Geographic, “Today's crocodilians are often said to be survivors from the age of dinosaurs. That's true as far as it goes: Modern crocs have been around for some 80 million years. But they're only a small sampling of the crocodilian relatives that once roamed the planet---and, in fact, once ruled it. Crurotarsans (a term paleontologists use to include all croc relatives) appeared about 240 million years ago, generally at the same time as dinosaurs. During the Triassic period, crocodile ancestors radiated into a wide array of terrestrial forms, from slender, long-legged animals something like wolves to huge, fearsome predators at the top of the food chain. Some, like the animal called Effigia, walked at least part of the time on two legs and were probably herbivores. So dominant were crurotarsans on land that dinosaurs were limited in the ecological niches they could occupy, staying mostly small in size and uncommon in number. [Source: Mel White, National Geographic , November 2009]

At the end of the Triassic, about 200 million years ago, an unknown cataclysm wiped out most crurotarsans. With the land cleared of their competitors, dinosaurs took over. At the same time, huge swimming predators such as plesiosaurs had evolved in the ocean, leaving little room for interlopers. The crocs that survived took on a new diversity of forms, but eventually they lived, as their descendants do today, in the only places they could: rivers, swamps, and marshes.

Restricted ecological niches may have limited the creatures' evolutionary opportunities---but also may have saved them. Many croc species survived the massive K-T (Cretaceous-Tertiary) extinction 65 million years ago, when an asteroid dealt a death blow to the dinosaurs (except for birds, now viewed as latter-day dinosaurs) and a broad range of other life on land and in the oceans. No one knows why crocs lived when so much died, but their freshwater habitat is one explanation: Freshwater species generally did better during the K-T event than did marine animals, which lost extensive shallow habitat as sea level dropped. Their wide-ranging diet and cold-blooded ability to go long periods without food may have helped as well. With land-based dinosaurs and sea monsters gone, why didn't crocs take over the Earth once and for all? By then mammals had begun their evolutionary march toward world domination. Over time the most divergent lines of crocs died out, leaving the squat-bodied, short-legged forms we're familiar with.



Dinosaur-Like Crocodiles

Some ancient ancestors of crocodiles looks more like dinosaurs than crocodiles. In 2006 Carl Zimmer wrote in the New York Times, Scientists at the American Museum of Natural History have discovered a fossil in New Mexico that looks like a six-foot-long, two-legged dinosaur similar to a tyrannosaur or a velociraptor. But it is actually an ancient relative of modern alligators and crocodiles. Carl Zimmer wrote in the New York Times, January 26, 2006

tThe reptile stood on its hind legs, keeping its tail erect. Its arms were tiny, its neck long, its eyes huge. It was toothless, and its jaws were covered in hard tissue, like a bird's beak. Although the 210-million-year-old fossil was more closely related to alligators and crocodiles, it bore an uncanny resemblance to a group of dinosaurs that evolved 80 million years later, known as ornithomimids, or ostrich-mimics. The similarity extends to subtle details, like air sacs in the vertebrae of both animals. Nesbitt and Norell named the fossil Effigia okeeffeae. Effigia means "ghost," referring to the decades that the fossil remained invisible to scientists. The species name honors the artist Georgia O'Keeffe, who lived not far from the fossil site. A paper describing their results will be published in The Proceedings of the Royal Society.

Effigia is a striking example of what biologists call convergence, when two lineages evolve the same body plan. Other examples of convergence include marsupials related to kangaroos and opossums that evolved into creatures resembling lions and wolves."When I first saw the skull, I thought this can't be related to crocs," said Christopher Brochu, an expert on crocodilian evolution at the University of Iowa. "But then I saw the ankle and said, 'Yep, it's a croc.' So ornithomimids were convergent on Effigia 80 million years later. There are only so many ways you can do something, and as a result you get this convergence."

Paul Sereno, a paleontologist from the University of Chicago, and his research team have uncovered fossils of a number of crocodile ancestors in the Sahara in Niger and Morocco that populated Gondwana--today's southern continents---approximately 110 million years ago. Described in a November 2009 National Geographic article, they include: 1) The BoarCroc is a 20-foot long meat-eater with an armor snout it used to ram and three sets of fangs for slicing. Eye sockets turned forward enhanced stereoscopic vision to aid in hunting. Large, well-developed muscles gave the jaw extra biting power. 2) The RacCroc has a pair of buckteeth in the lower jaw to allow this croc to burrow in the ground for tubers. 3) The DogCroc has differentiated teeth and a soft nose pointing forward, and possibly escaped from predators with its lanky legs. 4) The DuckCroc has a broad overhanging snout and hook-shaped teeth which helped it to catch small fish or worms in shallow water.

Super Croc

In 2000 in Gadoufaoua, a region of the Sahara in of Niger whose name means “where camels fear to go,” and one of Africa's richest sources of dinosaur fossils, Sereno found fossils of an awesome crocodile-like animal that scientists called Sarcosuchus imperator, a name that means "flesh crocodile emperor." Sereno's team nicknamed it "SuperCroc." The skull alone was six feet long! Sereno says it's "about the biggest I've ever seen." Based on the skull size and part of skeleton that was found and figuring the beast had the same basic configuration of modern crocodile, Sereno estimated that an adult SuperCroc could grow to be 40 feet long! That's roughly the length of a school bus. And the giant beast probably weighed as much as 10 tons. That's heavier than an African elephant. Those measurements make SuperCroc one of the largest crocodiles ever to walk the Earth. Today's biggest crocs grow to about 20 feet. [Source: Peter Winkler, National Geographic Classroom magazine, March 2002"

Peter Winkler wrote in National Geographic Classroom magazine: “Sereno believes SuperCroc lived about 110 million years ago when what is now the Sahara was covered by forests and was broken up rivers with masses of fish that SuperCroc fed on. Five or more crocodile species, or types, lurked in the rivers. SuperCroc, Sereno says, was "the monster of them all." What did SuperCroc eat. "Anything it wanted," Sereno says. SuperCroc's narrow jaws held about 130 teeth. The teeth were short but incredibly strong. SuperCroc's mouth was "designed for grabbing prey---fish, turtles, and dinosaurs that strayed too close." SuperCroc likely spent most of its life in the river. As is the cases with modern crocodiles water hid the creature's huge body. Only its eyes and nostrils poked above the surface. [Ibid]

“After spotting a meal, the giant hunter moved quietly toward the animal. Then---wham! That huge mouth locked onto its prey. SuperCroc dragged the stunned creature into the water. There the animal drowned. Then it became food. Dinosaurs surely fought back when SuperCroc grabbed them. But we don't know of any creatures that went after this huge reptile. Just in case, though, SuperCroc wore serious armor. Huge plates of bone, called scutes (skoots), covered the animal's back. Hundreds of them lay just below the skin. A single scute from the back could be a foot long! [Ibid]

“SuperCroc's long head is wider in front than in the middle. That shape is unique, or one of a kind. No other croc---living or extinct---has a snout quite like it. At the front of SuperCroc's head is a big hole. That's where the nose would be. That empty space may have given the ancient predator a keen sense of smell. Or perhaps it helped SuperCroc make noise to communicate with other members of its species. [Ibid]

“The giant beast probably lived only a few million years. That raises a huge question: Why didn't SuperCroc survive? Sereno suspects that SuperCrocs were fairly rare. After all, a monster that big needs plenty of room to make a living. Disease or disaster could have wiped out the species pretty quickly. But no one knows for sure what killed SuperCroc. That's a mystery for future scientists---maybe even you. [Ibid]



Crocodile Size, Speed, Sex and Age

Adult crocodiles range in size from three feet to more than 20 feet, and can weigh more than a ton. Large male crocodiles reach a certain length and then they start to broaden out so they look more like a tank than a crocodile. No one knows exactly how long a crocodile can live. Specimens in zoos have survived until their late 60s but some scientists speculate that some they may reach an age of 80 years old.

In July 2012, a huge crocodile known as Lolong was officially named the largest crocodile in captivity, the Guinness World Records. Lolong measures 20.24 feet (6.17 meters) and weighs more than a ton, Guinness spokeswoman Anne-Lise Rouse said in a statement. The Guinness website said: “Lolong’s weight was also measured at a nearby truck weigh-bridge and verified as approximately 1,075 kilograms. The reptile took the top spot from an Australian crocodile that measured more than 17 feet (5 meters) and weighed nearly a ton. See Saltwater Crocodiles

Crocodiles can run at speeds up to 25 mph. Crocodile expert Rob Bredl told National Geographic, "It's a myth that they can run as fast as a horse. They are big creatures with little short legs. But they can strike with amazing speed. In the water however crocodiles can surge forward short bursts at up to 50mph by tucking their front and rear legs in and thrusting with their powerful tails.” Some species can leap off the ground and stand on their hind legs to get at meat hung from a pole. Their tails are strong enough to dislocate a person’s jaw with a single whack.

Telling male and female crocodiles apart is very difficult. In the old days breeders often had to wait until female gave birth to say for sure she was a female. In some cases zoologist discovered that reason why a supposed “breeding” pair of crocodiles fought rather than mated was that they were both males. Today sex is determined by flipping a crocodile on its back and reaching up is rear end.

Crocodile Characteristics


crocodile skin

Crocodiles are considered to be more advanced than other reptiles. Their four-chambered hearts are almost as advanced as those of mammals and birds, allowing crocodiles to stay submerged underwater for as long as an hour by slowly pumping blood through their bodies. Crocodile and bird hearts have elaborate plumbing in their hearts with valves that keep oxygenated and unoxygenated blood separate. The reptile heart by contrast mixes the two kinds of blood. In cold weather alligators can saty underwater for up to 24 hours without breathing.

Crocodiles have a large chunk of skin in their throats called a palatal valve that prevents water from flowing into their lungs and drowning it when it opens its mouth. They also have muscles that pulls the liver backward, inflating the lungs. They serve the same purpose of a diaphragm in humans.

A crocodile’s bony, leathery skin is so tough that many bullets can not penetrate it. Natalie Angier wrote in the New York Times, “As scientists are just beginning to appreciate, that body plan is panzer, a tropical tank from the skin in. Beneath its scaly sheath and craggy osteoderms is another layer of armor, built of rows of bony overlapping shingles, or osteoscutes, that are both strong and flexible. And beneath that formidable barrier is an immune system that merits the modifier: it is virtually immune to defeat. [Source: Natalie Angier, New York Times, October 26, 2004]

The crocodile’s immune system is more powerful than that of humans. It is capable of killing the HIV virus and fending off severe infections and diseases that would kill people. “A crocodile wallows in mudholes, lagoons and other microbial Club Meds, yet it can suffer the most harrowing sort of injury - a limb torn off, its belly ripped open, its lower jaw sheared away - without so much as shedding a crocodile tear. "Crocodiles have tremendous robustness against bacterial infection," Dr. Ross said. "The sort of wound that would leave any of us severely septicemic doesn't seem to touch them." That immunological ferocity has inspired researchers at the Johns Hopkins to begin screening crocodile blood in search of new antibiotics.” [Ibid]

Crocodile Head and Sixth Sense


crocodile tooth

A crocodile’s ears, eyes and nostrils are located on the top of it head. This allows it to breath, hear, smell and see above water with just a small part of its body exposed. If you are brave enough to go swimming in croc infested waters keep your eyes pealed for beady crocodile eyes, peeping above the surface.<>

Crocodiles have no lips so water leaks in and out of their mouth. When they eat they have to lift their head out of the water so water doesn’t go down their throat and lift their head up so gravity forces the food down their throat. Even if a crocodile didn’t have any teeth, it could easily kill a man by crushing his skull with its powerful it jaws.

Crocodile eyes have a special transparent eyelids that can be closed when the animal submerges, allowing them to see under water. Crocodile pupils "tilt a little as the angle of the head changes, so that prey will always be in focus.” Wrestlers who flip a crocodile over and rub its stomach and “mesmerize” the crocodile or “put it to sleep” are actually disorienting the creature. Upside down the crocodile’s pupil's can't adjust and the world becomes nauseating conglomeration of images.

Some crocodilians have dark bumps all over their upper and lower jaws or all over their body. These bumps have nerves that are connected directly to the brain. For a long time it wasn’t known what these bumps did. In the early 2000s, it was discovered that they enable crocodilians to detect movement in the water. Alligators that were deprived of sight and hearing were able to swim directly to a drop of water using the bumps.

In the early 2000s, Dr. Daphne Soares, a neuroscientist at the University of Maryland, discovered a kind of sixth sense unique to crocodilians. Natalie Angier wrote in the New York Times, “She has determined that the mysterious little bumps found around the jaws of some crocodile species and across the entire bodies of others, which naturalists had long observed but never before understood, are sensory organs exquisitely suited to the demands of a semisubmerged ambush predator. The pigmented nodules encase bundles of nerve fibers that respond to the slightest disturbance in surface water and thus allow a crocodile to detect the signature of a potential meal - an approaching fish, a bathing heron, a luckless fawn enjoying its last lick of water.[Source: Natalie Angier, New York Times, October 26, 2004]

Crocodile Behavior


crocodiles like to sun themselves on mud banks

Crocodiles are considered to be more advanced than other reptiles mentally and socially as well as physically. They learn things faster than other reptiles and are the only reptiles capable of producing loud sounds. Dr. Daphne Soares, a neuroscientist at the University of Maryland, told the New York Times, “They get a bad rap for being stupid little reptiles. But they're very curious, very alert, and they want to know what's going on."

Crocodiles are social animals who communicate with hisses, grunts, chirps, burps and growls and infrasonic sounds. Physical displays include head slapping, body arching and bubble blowing. Natalie Angier wrote in the New York Times, Crocodilians “will engage in sophisticated behavior that leaves most reptiles in the cold. They vocalize to each other. They squabble over status and can distinguish between friendly hominid and annoying graduate student with dart gun. In caring for their young, they outcluck a mother hen, for what hen can protect her babies by carrying them in her jaw? "They're not like big lizards," said Dr. George Amato, a geneticist at the Wildlife Conservation Society, a division of the Bronx Zoo. "It's clear when you spend time with them that they are quite complex." [Source: Natalie Angier, New York Times, October 26, 2004]

Male crocodiles are very territorial and status conscious. They establish a hierarchy that allows them live in crowded conditions and avoid battles. One scientist told the New York Times, “Crocodiles known their neighbors for miles around, and they know who’s who, who’s inferior, who’s superior.” This helps them live to ripe old ages.

Crocodiles swallow rocks. No one knows why they do this. It is believed to be related to their ancestry with birds (some birds and other animals too swallow pebbles to aid their digestion). Studies have shown that crocodiles swallow stones equivalent to one percent of their body weight no matter how big they are. In one study, a growing crocodile with only big rocks present would swallow some big stones and regurgitate some smaller one to get the body weight just right.

Crocodiles on the Hunt


Crocodiles spend most of their time doing nothing. Rather than pursue prey they are opportunists, who lurk in shallow, murky tea-colored water waiting for fish or turtle to come floating their way or for some land animal to come within striking distance of the shore. Dangling arms and legs can attract crocodiles. Sometimes they bite paddles.

Crocodiles that attack animals usually wait for the animals to come to drink and grab their victim by the leg or sometimes by the snout and pull it into the water. To avoid encounters with crocodiles many animals prefer to drink from tributary springs rather than rivers deep enough to support crocodiles.

Crocodiles can scull very quietly through the water with their tails. They can approach river banks with barely ripple to give away their presence. Wildlife photographer Mark Deeble said that usually crocodiles “lie silent and submerged in water, only their eyes, nostrils and ears breaking the surface. When an animal comes...their eyes vanish from the water with a ripple. Then suddenly they burst from the water in a splashing furry and lunge, jaws open, for their prey."

Crocodiles on the Attack


crocodile attacking a tiger

The attack zone of a large crocodile is about a two meter semicircle in front of the attacking reptile. This is the distance that a crocodile can lunge and seize its prey. Beyond two meters is out of the croc’s range. During an attack a crocodile uses: 1) its powerful legs to push itself upwards; 2) its powerful tail to surge forward; and its powerful jaws to grasp the prey.

Even though crocodiles have big teeth they generally don't kill their victims by biting them. Rather they clamp onto their prey with their powerful vice-like jaws and pull them underwater. Victim usually die from drowning. In some cases the crocodile performs a “death roll” and twists the body of their victims enough to break their necks. If an animal is too large to drown the crocodile may kill it by eating out its intestines, heart and liver. When it eats it twists off chunks of meat.

Although crocodiles are extremely powerful animals they tire easily. Unless they quickly drown their victims, fights can drag on for over an hour, with the crocodile spending most of its time clamped on to their victim, just sitting there and resting until it can resume the fight. Their palatal valve can be used to seal off the throat so a crocodile can bite underwater without getting water into its lungs or stomach. <>

The only animals that present a real danger to crocodiles are humans and other crocodiles. Few animals attack full grown crocodiles. Their nests however are vulnerable to pilfering mongooses, vultures, monitor lizards and other predators. Young crocodiles are sometimes taken by large birds such as eagles and herons. Mother crocodiles have to be particularly watchful for six foot tall goliath herons. Adult males often eat baby crocodiles, so will females when presses. Mothers will even eat their own young so that she and other members of her brood can survive.

Feeding Crocodile


Crocodiles tend to hunt rough fish undesirable for human consumption. They eat relatively infrequently. Often many days pass between meals Like other large cold-blooded animals with slow metabolism crocodiles can survive long periods---up to two years---without eating.<>

Crocodiles can only grip and rip with their massive jaws, they can not chew. Their teeth are designed for grasping and holding prey rather than cutting off pieces of meat. To break off a hunk of meat from large prey a crocodile grabs a hold of the carcass and twists its body around like a child rolling down a hill. Pieces as large as a goat head can be swallowed whole and large chunks of meat are beaten against the surface of the water to break them into smaller pieces and soften them up. With smaller prey crocodiles often move their heads from side to side when. This allows them to slam their jaws and expel water without also losing fish in their mouth.

Crocodile can only digest a relatively small amount of food. Their stomachs are relatively small and need time break down large gulped down hunks of meat with acids secreted by the stomach powerful enough to dissolve bones and cartilage. Large carcasses are stashed away and eaten little by little. Crocodiles have few competitors so they can store their kills and eat over several days.

Male Crocodiles


crocodile mud track

River colonies of crocodiles are often ruled by massive dominant males that, among other things, control which crocodiles bask where on sand bars in the middle of the river. Sometimes these males slap their head on the water express territoriality and small males stupid enough to intrude are attacked and sometimes killed and eaten. To avoid trouble small males that pass near the large male's territory must lift up their head and expose their throat, an act of submission.

Large males sometimes slap their head on the water to express territoriality. Small intruders are attacked and sometimes killed and eaten. Aggressive males sometimes take bites out of other adult crocodiles. Some males lose all their teeth in fights with other males.

Describing the water dance of male crocodile, Diane Ackerman wrote in A Natural History of the Senses : "Stretching its enormous head out of the water, it puffs up its throat , tenses like a body builder, and a rolling thunder-buster bellow splits the air, and the water sizzles all around its body, raining upwards like frying diamonds. We see the water dance, but other [crocodiles] hear its infrasonic signal, made only by other males, perhaps as a courtship display or perhaps also as a full-body raspberry directed at other males." [Source: Diane Ackerman, A Natural History of the Senses, Vintage Books, 1990]

Natalie Angier wrote in the New York Times, “For their part, male crocodiles are as territorial and status-conscious as are male birds, and they establish hierarchies that allow them to live in often crowded conditions without needing to risk their lives repeatedly in battle. Their aversion to potentially lethal acts of showmanship, coupled with the many hours they spend in the crocodilian zen of vigilant stillness, allows them to live for half a century or longer. Crocodiles don't like to make waves, though when they're hungry, they sure like to feel them. [Source: Natalie Angier, New York Times, October 26, 2004]

Crocodile Mating and Females and Their Young

During the mating season a male crocodile rubs his body against the female. Crocodiles have numerous touch receptors around their heads which are used in elaborate touching and stroking during mating. Before copulation he positions himself on top of the female by biting into the females necks and wrapping his legs around hers. Sex usually last for only around three minutes. Sex often takes place on a shallow mudbank. When it takes place in the water the female is often completely submerged.

20080318-Chinese alligator adult chinese alligator fund2.gif
Mother Chinese alligator
and young
Crocodiles lay their eggs in decaying plant material. Female crocodiles usually lay between 40 and 80 brittle eggs. After they have been deposited in a small hole that the mother digs with her hind legs the eggs are covered with dirt. The eggs usually hatch about two or three months later.

Unlike most reptiles, crocodiles stay with their eggs until they are hatched and viciosuly defends them. Often times the mother doesn't move from the nest the entire time---not even to eat---and growls at anything that comes within a hundred yards of the nest. One scientist observed a female who only ate once during the entire three month period.

When the first hatchling chirp the mother digs up the nest, and both the male and female watch over the young crocodiles for the first two months of their life, while they learn to hunt frogs and insects. An adult female crocodile picks up her young with her teeth and carries them young around in a pouch at the bottom of her mouth. The pouch forms only after she hears the chirping of her babies. Some negligent mothers fail to react when the baby crocodiles start to hatch, and the young either suffocate or the eggs rot.

If the eggs get dry the mother urinates on them. When the hatchlings emerge they cheep like chicks, The mother responded by uncovering the nest and carrying the newborns to the water.. Mothers may stay with their young for a couple of years, protecting them from predators and helping them find food when food is scarce. Some crocodiles have been observed leading their young to food sources by vocalization exchanges.

Few animals attack full grown crocodiles, but nests are vulnerable to pilfering mongooses, vultures, monitor lizards and other predators. Young crocodiles are sometimes taken by large birds such as eagles and herons. The six foot tall goliath heron can be especially deadly.

Image Sources: Wikimedia Commons

Text Sources: National Geographic, Natural History magazine, Smithsonian magazine, Wikipedia, New York Times, Washington Post, Los Angeles Times, Times of London, The Guardian, Top Secret Animal Attack Files website, The New Yorker, Time, Newsweek, Reuters, AP, AFP, The Economist, BBC, and various books and other publications.

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© 2008 Jeffrey Hays

Last updated November 2012

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