Crocodiles or true crocodiles are large aquatic reptiles that live throughout the tropics in Africa, Asia, the Americas and Australia. Crocodylinae, all of whose members are considered true crocodiles, is classified as a biological subfamily.
Scientific name: Crocodylinae
Lifespan: Saltwater crocodile: 70 years, Nile crocodile: 70 – 100 years
Speed: Saltwater crocodile: 15 – 18 mph, Nile crocodile: 19 – 22 mph, American crocodile: 20 mph
Mass: Saltwater crocodile: 880 – 2,200 lbs, Nile crocodile: 500 – 1,200 lbs, American crocodile: 880 – 1,100 lbs
Length: Saltwater crocodile: 14 – 17 ft., Nile crocodile: 14 ft., American crocodile: 13 – 16 ft.
History of Crocodile
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.
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.
Crocodiles range in size from the African dwarf crocodile, which grows to over 6 feet, to the Saltwater crocodile, which grows to over 20 feet in length. Crocodiles have large, broad bodies with short legs and long, muscular tails. They have thick, leathery skin with bony, plate-shaped scales. All crocodile teeth are pointed, cone shaped and located on the outside of the jaws. Crocodile heads are long and pointed with the eyes and nostrils located on the top of the head. Crocodiles never stop growing; the older the animal is, the larger it is and some species live for up to 75 years.
The Crocodile breeding season is from January to May. For males, the onset of sexual maturity occurs when they are about 3 meters (10 feet) in length, while for females, it occurs when they reach 2 to 2.5 meters (6.5 to 8 feet) in length. This takes about 10 years for both male and females crocodiles to reach these lengths under normal conditions. During the mating season, males attract females by bellowing, slapping their snouts in the water, blowing water of out their noses and making a variety of vocalizations. The larger males of a population tend to be more successful. Once a female has been attracted, the pair warble and rubs the underside of their jaws together.
After crocodiles mate, the female crocodile lays about 20 – 40 eggs (a clutch) in a nest she makes near a river bank once a year. She covers the nest with leaves and other vegetation. The rotting vegetation keeps the eggs warm and the nest moist. The incubation temperature for crocodile eggs is 28 – 32 degrees Celsius, relative humidity is 95 – 100 percent, the incubation period is 70 – 80 days. The female stays and guards the nest until the eggs hatch. The hatchlings call out and the female crocodile opens up the nest and carries them to the water, where they immediately start feeding on crabs, shrimps, and insects. About half will not survive the first year due to predators.
American crocodiles inhabit brackish and saltwater habitats and are typically found in coastal mangrove wetlands, ponds, coves, creeks, and canals. Decidedly less aggressive than the infamous Nile and Australian crocodiles, American crocodiles are shy, reclusive and rarely seen by people.
Crocodile and Human
The larger species of crocodiles can be very dangerous to humans. The Saltwater and Nile Crocodiles are the most dangerous, killing hundreds of people each year in parts of South-East Asia and Africa. Mugger crocodiles and possibly the endangered Black Caiman, are also very dangerous to humans. American alligators are less aggressive and rarely assault humans without provocation.
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.”
Types of Crocodile
Crocodiles Life Span
The oldest crocodilians are estimated to have lived around 71 years on average and there is limited evidence that some individuals may exceed 100 years. One of the oldest crocodiles recorded died in a zoo in Russia apparently aged 115 years old.
Crocodiles are entirely carnivorous and have the most potent stomach acid of any vertebrate animal, so they are able to digest bone and shell. They will feed on any animal they are large enough to tackle. In the case of saltwater crocodiles, this could be just about any animal. Smaller species are limited to smaller prey and some specialize in animals like turtles and shellfish. Crocodiles are ambush predators and will often swim close to their prey as it drinks from the river. The crocodile then uses its powerful tail to lunge forward so it can bite its prey, trapping it in powerful, toothsome jaws.
Once hunted intensively for their hides, today, loss of habitat to human development, illegal killing and roadkill are the greatest threats faced by American crocodiles. As sea level rises due to climate change, a significant portion of crocodiles’ coastal wetland habitat may face saltwater incursion or inundation.
Facts about Crocodiles
- Crocodiles can swim at 25mph just with the help of their powerful tail.
- Farmed crocodiles can reach 1.5 meters (5ft) in length in just one year.
- When crocodiles sit on river banks with their mouths opens, it’s not aggression. They’re trying to cool off as they sweat through their mouths.
- Crocodiles display increased aggressiveness during the mating season, which is linked to the monsoon.
- Each crocodile jaw has 24 teeth that are meant to grasp and crush, not chew. They swallow stones that grind food inside their stomachs and also act as ballast.
- Ninety-nine percent of crocodile offspring is eaten in the first year of birth, by large fish, herons, monitor lizards and adult crocodiles.
- Crocodile skin is considered one of the finest, treasured for its durability and softness. It’s a sign of status in tribal societies.
- Some tribes, like those in New Guinea, venerate the crocodile and give themselves scarring to match that of a crocodile skin.
- Crocodiles, which first appeared 240 million years ago, can live up to 80 years.
- “Crying crocodile tears” displaying fake sadness comes from the myth that the reptiles weep when eating humans. They do wipe their eyes when feeding, but only because their eyes bubble and froth when eating.
- Crocodiles use their teeth to tear apart their prey after clamping them down in their jaws. Then, they will simply swallow the torn apart prey.
- Saltwater crocodiles are the largest ones. The largest one ever found was an astonishing 20.24 feet long.
- Crocodiles are really ancient. They actually coexisted with dinosaurs. Crocodiles have been around for at least 240 million years.
- Crocs can live in a number of places like lakes, rivers, freshwater bodies, salt water, brackish water brackish water is a mixture of salt and freshwater.
- Crocodiles are found in many places. They are usually found in tropical regions of Asia, Australia, Africa and Americas.
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