Crocodile

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For other uses, see Crocodile (disambiguation). Crocodile_sentence_0

Crocodile_table_infobox_0

Crocodiles

Temporal range: EoceneHolocene, 55–0 Ma PreꞒ O S D C P T J K Pg NCrocodile_header_cell_0_0_0

Scientific classification CrocodylinaeCrocodile_header_cell_0_1_0
Kingdom:Crocodile_cell_0_2_0 AnimaliaCrocodile_cell_0_2_1
Phylum:Crocodile_cell_0_3_0 ChordataCrocodile_cell_0_3_1
Class:Crocodile_cell_0_4_0 ReptiliaCrocodile_cell_0_4_1
Order:Crocodile_cell_0_5_0 CrocodiliaCrocodile_cell_0_5_1
Family:Crocodile_cell_0_6_0 CrocodylidaeCrocodile_cell_0_6_1
Subfamily:Crocodile_cell_0_7_0 Crocodylinae

Cuvier, 1807Crocodile_cell_0_7_1

Type speciesCrocodile_header_cell_0_8_0
GeneraCrocodile_header_cell_0_9_0

Crocodiles (subfamily Crocodylinae) or true crocodiles are large semiaquatic reptiles that live throughout the tropics in Africa, Asia, the Americas and Australia. Crocodile_sentence_1

Crocodylinae, all of whose members are considered true crocodiles, is classified as a biological subfamily. Crocodile_sentence_2

A broader sense of the term crocodile, Crocodylidae (which includes Tomistoma), is not used in this article. Crocodile_sentence_3

The term crocodile here applies to only the species within the subfamily of Crocodylinae. Crocodile_sentence_4

The term is sometimes used even more loosely to include all extant members of the order Crocodilia, which includes the alligators and caimans (family Alligatoridae), the gharial and false gharial (family Gavialidae), and all other living and fossil Crocodylomorpha. Crocodile_sentence_5

Although they appear similar, crocodiles, alligators and the gharial belong to separate biological families. Crocodile_sentence_6

The gharial, with its narrow snout, is easier to distinguish, while morphological differences are more difficult to spot in crocodiles and alligators. Crocodile_sentence_7

The most obvious external differences are visible in the head, with crocodiles having narrower and longer heads, with a more V-shaped than a U-shaped snout compared to alligators and caimans. Crocodile_sentence_8

Another obvious trait is that the upper and lower jaws of the crocodiles are the same width, and the teeth in the lower jaw fall along the edge or outside the upper jaw when the mouth is closed; therefore, all teeth are visible, unlike an alligator, which possesses in the upper jaw small depressions into which the lower teeth fit. Crocodile_sentence_9

Also, when the crocodile's mouth is closed, the large fourth tooth in the lower jaw fits into a constriction in the upper jaw. Crocodile_sentence_10

For hard-to-distinguish specimens, the protruding tooth is the most reliable feature to define the species' family. Crocodile_sentence_11

Crocodiles have more webbing on the toes of the hind feet and can better tolerate saltwater due to specialized salt glands for filtering out salt, which are present, but non-functioning, in alligators. Crocodile_sentence_12

Another trait that separates crocodiles from other crocodilians is their much higher levels of aggression. Crocodile_sentence_13

Crocodile size, morphology, behaviour and ecology differ somewhat among species. Crocodile_sentence_14

However, they have many similarities in these areas as well. Crocodile_sentence_15

All crocodiles are semiaquatic and tend to congregate in freshwater habitats such as rivers, lakes, wetlands and sometimes in brackish water and saltwater. Crocodile_sentence_16

They are carnivorous animals, feeding mostly on vertebrates such as fish, reptiles, birds and mammals, and sometimes on invertebrates such as molluscs and crustaceans, depending on species and age. Crocodile_sentence_17

All crocodiles are tropical species that, unlike alligators, are very sensitive to cold. Crocodile_sentence_18

They separated from other crocodilians during the Eocene epoch, about 55 million years ago. Crocodile_sentence_19

Many species are at the risk of extinction, some being classified as critically endangered. Crocodile_sentence_20

Etymology Crocodile_section_0

The word "crocodile" comes from the Ancient Greek κροκόδιλος (crocodilos), "lizard", used in the phrase ho krokódilos tou potamoú, "the lizard of the (Nile) river". Crocodile_sentence_21

There are several variant Greek forms of the word attested, including the later form κροκόδειλος (crocodeilos) found cited in many English reference works. Crocodile_sentence_22

In the Koine Greek of Roman times, crocodilos and crocodeilos would have been pronounced identically, and either or both may be the source of the Latinized form crocodīlus used by the ancient Romans. Crocodile_sentence_23

It has been suggested, but it is not certain that the word crocodilos or crocodeilos is a compound of krokè ("pebbles"), and drilos/dreilos ("worm"), although drilos is only attested as a colloquial term for "penis". Crocodile_sentence_24

It is ascribed to Herodotus, and supposedly describes the basking habits of the Egyptian crocodile. Crocodile_sentence_25

The form crocodrillus is attested in Medieval Latin. Crocodile_sentence_26

It is not clear whether this is a medieval corruption or derives from alternative Greco-Latin forms (late Greek corcodrillos and corcodrillion are attested). Crocodile_sentence_27

A (further) corrupted form cocodrille is found in Old French and was borrowed into Middle English as cocodril(le). Crocodile_sentence_28

The Modern English form crocodile was adapted directly from the Classical Latin crocodīlus in the 16th century, replacing the earlier form. Crocodile_sentence_29

The use of -y- in the scientific name Crocodylus (and forms derived from it) is a corruption introduced by Laurenti (1768). Crocodile_sentence_30

Species Crocodile_section_1

A total of 16 extant species have been recognized. Crocodile_sentence_31

Further genetic study is needed for the confirmation of proposed species under the genus Osteolaemus, which is currently monotypic. Crocodile_sentence_32

Crocodile_table_general_1

Species nameCrocodile_header_cell_1_0_0 ImageCrocodile_header_cell_1_0_1 DistributionCrocodile_header_cell_1_0_2 Description/CommentsCrocodile_header_cell_1_0_3
American crocodile (Crocodylus acutus)Crocodile_cell_1_1_0 Crocodile_cell_1_1_1 Throughout the Caribbean Basin, including many of the Caribbean islands and South Florida.Crocodile_cell_1_1_2 A larger sized species, with a greyish colour and a prominent V-shaped snout. Prefers brackish water, but also inhabits lower stretches of rivers and true marine environments. This is one of the rare species that exhibits regular sea-going behaviour, which explains the great distribution throughout the Caribbean. It is also found in hypersaline lakes such as Lago Enriquillo, in the Dominican Republic, which has one of the largest populations of this species. Diet consists mostly of aquatic and terrestrial vertebrates. Classified as Vulnerable, but certain local populations under greater threat.Crocodile_cell_1_1_3
Hall's New Guinea crocodile (Crocodylus halli)Crocodile_cell_1_2_0 Crocodile_cell_1_2_1 The island of New Guinea, south of the New Guinea HighlandsCrocodile_cell_1_2_2 A smaller species that closely resembles and was long classified under the New Guinea crocodile, which it is now considered to be genetically distinct from. It lives south of the mountain barrier that divides the two species' ranges. It can be physically distinguished from the New Guinea crocodile by its shorter maxilla and enlarged postcranial elements. Cranial elements can still widely vary within the species, with populations from Lake Murray having much wider heads than those from the Aramia River.Crocodile_cell_1_2_3
Orinoco crocodile (Crocodylus intermedius)Crocodile_cell_1_3_0 Crocodile_cell_1_3_1 Colombia and VenezuelaCrocodile_cell_1_3_2 This is a large species with a relatively elongated snout and a pale tan coloration with scattered dark brown markings. Lives primarily in the Orinoco Basin. Despite having a rather narrow snout, preys on a wide variety of vertebrates, including large mammals. It is a Critically Endangered species.Crocodile_cell_1_3_3
Freshwater crocodile (Crocodylus johnstoni)Crocodile_cell_1_4_0 Crocodile_cell_1_4_1 Northern AustraliaCrocodile_cell_1_4_2 A smaller species with a narrow and elongated snout. It has light brown coloration with darker bands on body and tail. Lives in rivers with considerable distance from the sea, to avoid confrontations with saltwater crocodiles. Feeds mostly on fish and other small vertebrates.Crocodile_cell_1_4_3
Philippine crocodile (Crocodylus mindorensis)Crocodile_cell_1_5_0 Crocodile_cell_1_5_1 Endemic to the PhilippinesCrocodile_cell_1_5_2 This is a relatively small species with a rather broader snout. It has heavy dorsal armour and a golden-brown colour that darkens as the animal matures. Prefers freshwater habitats and feeds on a variety of small to medium sized vertebrates. This species is Critically Endangered and the most severely threatened species of crocodile.Crocodile_cell_1_5_3
Morelet's crocodile (Crocodylus moreletii)Crocodile_cell_1_6_0 Crocodile_cell_1_6_1 Atlantic regions of Mexico, Belize and GuatemalaCrocodile_cell_1_6_2 A small to medium sized crocodile with a rather broad snout. It has a dark greyish-brown colour and is found in mostly various freshwater habitats. Feeds on mammals, birds and reptiles. It is listed as Least Concern.Crocodile_cell_1_6_3
Nile crocodile (Crocodylus niloticus)Crocodile_cell_1_7_0 Crocodile_cell_1_7_1 Sub-saharan AfricaCrocodile_cell_1_7_2 A large and aggressive species with a broad snout, especially in older animals. It has a dark bronze coloration and darkens as the animal matures. Lives in a variety of freshwater habitats but is also found in brackish water. It is an apex predator that is capable of taking a wide array of African vertebrates, including large ungulates and other predators. This species is listed as Least Concern.Crocodile_cell_1_7_3
New Guinea crocodile (Crocodylus novaeguineae)Crocodile_cell_1_8_0 Crocodile_cell_1_8_1 The island of New Guinea, north of the New Guinea HighlandsCrocodile_cell_1_8_2 A smaller species of crocodile with a grey-brown colour and dark brown to black markings on the tail. The young have a narrower V-shaped snout that becomes wider as the animal matures. Prefers freshwater habitats, even though is tolerant to salt water, in order to avoid competition and predation by the saltwater crocodile. This species feeds on small to mid-sized vertebrates.Crocodile_cell_1_8_3
Mugger crocodile (Crocodylus palustris)Crocodile_cell_1_9_0 Crocodile_cell_1_9_1 The Indian subcontinent and surrounding countriesCrocodile_cell_1_9_2 This is a modest sized crocodile with a very broad snout and an alligator-like appearance. It has dark-grey to brown coloration. Enlarged scutes around the neck make it a heavily armoured species. Prefers slow moving rivers, swamps and lakes. It can also be found in coastal swamps but avoids areas populated by saltwater crocodiles. Feeds on a wide array of vertebrates.Crocodile_cell_1_9_3
Saltwater crocodile (Crocodylus porosus)Crocodile_cell_1_10_0 Crocodile_cell_1_10_1 Throughout Southeast Asia, Northern Australia and surrounding watersCrocodile_cell_1_10_2 The largest living reptile and most aggressive of all crocodiles. It is a big-headed species and has a relatively broad snout, especially when older. The coloration is pale yellow with black stripes when young but dark greenish-drab coloured as adults. Lives in brackish and marine environments as well as lower stretches of rivers. This species has the greatest distribution of all crocodiles. Tagged specimens showed long-distance marine travelling behaviour. It is the apex predator throughout its range and preys on virtually any animal within its reach. It is classified as Least Concern with several populations under greater risk.Crocodile_cell_1_10_3
Borneo crocodile (Crocodylus raninus)Crocodile_cell_1_11_0 Crocodile_cell_1_11_1 Island of Borneo in Southeast AsiaCrocodile_cell_1_11_2 A freshwater species of crocodile that has been considered a synonym of the saltwater crocodile.Crocodile_cell_1_11_3
Cuban crocodile (Crocodylus rhombifer)Crocodile_cell_1_12_0 Crocodile_cell_1_12_1 Found only in the Zapata Swamp and Isle of Youth of CubaCrocodile_cell_1_12_2 It is a small but extremely aggressive species of crocodile that prefers freshwater swamps. The coloration is vibrant even as adults and the scales have a "pebbled" appearance. It is a relatively terrestrial species with agile locomotion on land, and sometimes displays terrestrial hunting. The snout is broad with a thick upper-jaw and large teeth. The unique characteristics and fossil record indicates a rather specialized diet in the past, preying on megafauna such as the giant sloth. This species sometimes displays pack-hunting behaviour, which might have been the key to hunting large species in the past, despite its small size. Today most prey are small to medium sized vertebrates. It is Critically Endangered, and the remaining wild population is under threat of hybridization.Crocodile_cell_1_12_3
Siamese crocodile (Crocodylus siamensis)Crocodile_cell_1_13_0 Crocodile_cell_1_13_1 Indonesia, Brunei, East Malaysia and southern IndochinaCrocodile_cell_1_13_2 A fairly small crocodile that prefers freshwater habitats. It has a relatively broad snout and olive-green to dark green coloration. It feeds on a variety of small to mid-sized vertebrates. Listed as Critically Endangered, but might be already extinct in the wild; status is unknown.Crocodile_cell_1_13_3
West African crocodile (Crocodylus suchus)Crocodile_cell_1_14_0 Crocodile_cell_1_14_1 Western and Central AfricaCrocodile_cell_1_14_2 Recent studies revealed that this is distinct species from the larger Nile crocodile. It has a slightly narrower snout and is much smaller compared to its larger cousin.Crocodile_cell_1_14_3
Dwarf crocodile (Osteolaemus tetraspis)Crocodile_cell_1_15_0 Crocodile_cell_1_15_1 Western AfricaCrocodile_cell_1_15_2 It is the smallest of all living crocodiles. It belongs to its own monotypic genus; however, new studies indicate there might be two or even three distinct species. It is a heavily armoured species with uniform black coloration in adults, while juveniles have a lighter brown banding. Lives in the tropical forests of Western Africa. Feeds on small vertebrates and large aquatic invertebrates. It is a fairly terrestrial species and exhibits terrestrial hunting, especially at night. This species is classified as Vulnerable.Crocodile_cell_1_15_3
West African slender-snouted crocodile (Mecistops cataphractus)Crocodile_cell_1_16_0 Crocodile_cell_1_16_1 Western AfricaCrocodile_cell_1_16_2 A medium sized species with a narrow and elongated snout. Lives in freshwater habitats within tropical forests of the continent. Feeds mostly on fish but also other small to medium sized vertebrates. It is a Critically Endangered species.Crocodile_cell_1_16_3
Central African slender-snouted crocodile (Mecistops leptorhynchus)Crocodile_cell_1_17_0 Crocodile_cell_1_17_1 Central AfricaCrocodile_cell_1_17_2 A medium sized species found in watery areas in dense rainforest. Feeds largely on fish. Insufficient conservation data, but was classified as Critically Endangered when lumped with M. cataphractus, although M. leptorhynchus is doing better in its home range.Crocodile_cell_1_17_3

For information on Tomistoma or false gharial, that is recently not considered as a true crocodile, see False gharial. Crocodile_sentence_33

Characteristics Crocodile_section_2

Crocodiles are similar to alligators and caimans; for their common characteristics and differences among them, see Crocodilia. Crocodile_sentence_34

A crocodile's physical traits allow it to be a successful predator. Crocodile_sentence_35

Its external morphology is a sign of its aquatic and predatory lifestyle. Crocodile_sentence_36

Its streamlined body enables it to swim swiftly; it also tucks its feet to the side while swimming, making it faster by decreasing water resistance. Crocodile_sentence_37

Crocodiles have webbed feet which, though not used to propel them through the water, allow them to make fast turns and sudden moves in the water or initiate swimming. Crocodile_sentence_38

Webbed feet are an advantage in shallow water, where the animals sometimes move around by walking. Crocodile_sentence_39

Crocodiles have a palatal flap, a rigid tissue at the back of the mouth that blocks the entry of water. Crocodile_sentence_40

The palate has a special path from the nostril to the glottis that bypasses the mouth. Crocodile_sentence_41

The nostrils are closed during submergence. Crocodile_sentence_42

Like other archosaurs, crocodilians are diapsid, although their post-temporal fenestrae are reduced. Crocodile_sentence_43

The walls of the braincase are bony but lack supratemporal and postfrontal bones. Crocodile_sentence_44

Their tongues are not free, but held in place by a membrane that limits movement; as a result, crocodiles are unable to stick out their tongues. Crocodile_sentence_45

Crocodiles have smooth skin on their bellies and sides, while their dorsal surfaces are armoured with large osteoderms. Crocodile_sentence_46

The armoured skin has scales and is thick and rugged, providing some protection. Crocodile_sentence_47

They are still able to absorb heat through this armour, as a network of small capillaries allows blood through the scales to absorb heat. Crocodile_sentence_48

The osteoderms are highly vascularised and aid in calcium balance, both to neutralize acids while the animal cannot breathe underwater and to provide calcium for eggshell formation. Crocodile_sentence_49

Crocodilian scales have pores believed to be sensory in function, analogous to the lateral line in fishes. Crocodile_sentence_50

They are particularly seen on their upper and lower jaws. Crocodile_sentence_51

Another possibility is that they are secretory, as they produce an oily substance which appears to flush mud off. Crocodile_sentence_52

Size Crocodile_section_3

Size greatly varies among species, from the dwarf crocodile to the saltwater crocodile. Crocodile_sentence_53

Species of the dwarf crocodile Osteolaemus grow to an adult size of just 1.5 to 1.9 m (4.9 to 6.2 ft), whereas the saltwater crocodile can grow to sizes over 7 m (23 ft) and weigh 1,000 kg (2,200 lb). Crocodile_sentence_54

Several other large species can reach over 5.2 m (17 ft) long and weigh over 900 kg (2,000 lb). Crocodile_sentence_55

Crocodilians show pronounced sexual dimorphism, with males growing much larger and more rapidly than females. Crocodile_sentence_56

Despite their large adult sizes, crocodiles start their lives at around 20 cm (7.9 in) long. Crocodile_sentence_57

The largest species of crocodile is the saltwater crocodile, found in eastern India, northern Australia, throughout South-east Asia, and in the surrounding waters. Crocodile_sentence_58

The brain volume of two adult crocodiles was 5.6 cm for a spectacled caiman and 8.5 cm for a larger Nile crocodile. Crocodile_sentence_59

The largest crocodile ever held in captivity is a saltwater–Siamese hybrid named Yai (Thai: ใหญ่, meaning big; born 10 June 1972) at the Samutprakarn Crocodile Farm and Zoo, Thailand. Crocodile_sentence_60

This animal measures 6 m (20 ft) in length and weighs 1,114 kg (2,456 lb). Crocodile_sentence_61

The longest crocodile captured alive was Lolong, a saltwater crocodile which was measured at 6.17 m (20.2 ft) and weighed at 1,075 kg (2,370 lb) by a National Geographic team in Agusan del Sur Province, Philippines. Crocodile_sentence_62

Teeth Crocodile_section_4

Crocodiles are polyphyodonts; they are able to replace each of their 80 teeth up to 50 times in their 35- to 75-year lifespan. Crocodile_sentence_63

Next to each full-grown tooth, there is a small replacement tooth and an odontogenic stem cell in the dental lamina in standby that can be activated if required. Crocodile_sentence_64

Biology and behaviour Crocodile_section_5

Crocodilians are more closely related to birds and dinosaurs than to most animals classified as reptiles, the three families being included in the group Archosauria ('ruling reptiles'). Crocodile_sentence_65

Despite their prehistoric look, crocodiles are among the more biologically complex reptiles. Crocodile_sentence_66

Unlike other reptiles, a crocodile has a cerebral cortex and a four-chambered heart. Crocodile_sentence_67

Crocodilians also have the functional equivalent of a diaphragm by incorporating muscles used for aquatic locomotion into respiration. Crocodile_sentence_68

Salt glands are present in the tongues of crocodiles and they have a pore opening on the surface of the tongue, a trait that separates them from alligators. Crocodile_sentence_69

Salt glands are dysfunctional in Alligatoridae. Crocodile_sentence_70

Their function appears to be similar to that of salt glands in marine turtles. Crocodile_sentence_71

Crocodiles do not have sweat glands and release heat through their mouths. Crocodile_sentence_72

They often sleep with their mouths open and may pant like a dog. Crocodile_sentence_73

Four species of freshwater crocodile climb trees to bask in areas lacking a shoreline. Crocodile_sentence_74

Senses Crocodile_section_6

Crocodiles have acute senses, an evolutionary advantage that makes them successful predators. Crocodile_sentence_75

The eyes, ears and nostrils are located on top of the head, allowing the crocodile to lie low in the water, almost totally submerged and hidden from prey. Crocodile_sentence_76

Vision Crocodile_section_7

Crocodiles have very good night vision, and are mostly nocturnal hunters. Crocodile_sentence_77

They use the disadvantage of most prey animals' poor nocturnal vision to their advantage. Crocodile_sentence_78

The light receptors in crocodilians' eyes include cones and numerous rods, so it is assumed all crocodilians can see colours. Crocodile_sentence_79

Crocodiles have vertical-slit shaped pupils, similar to those of domestic cats. Crocodile_sentence_80

One explanation for the evolution of slit pupils is that they exclude light more effectively than a circular pupil, helping to protect the eyes during daylight. Crocodile_sentence_81

On the rear wall of the eye is a tapetum lucidum, which reflects incoming light back onto the retina, thus utilizing the small amount of light available at night to best advantage. Crocodile_sentence_82

In addition to the protection of the upper and lower eyelids, crocodiles have a nictitating membrane (sometimes called a "third eye-lid") that can be drawn over the eye from the inner corner while the lids are open. Crocodile_sentence_83

The eyeball surface is thus protected under the water while a certain degree of vision is still possible. Crocodile_sentence_84

Olfaction Crocodile_section_8

Crocodilian sense of smell is also very well developed, aiding them to detect prey or animal carcasses that are either on land or in water, from far away. Crocodile_sentence_85

It is possible that crocodiles use olfaction in the egg prior to hatching. Crocodile_sentence_86

Chemoreception in crocodiles is especially interesting because they hunt in both terrestrial and aquatic surroundings. Crocodile_sentence_87

Crocodiles have only one olfactory chamber and the vomeronasal organ is absent in the adults indicating all olfactory perception is limited to the olfactory system. Crocodile_sentence_88

Behavioural and olfactometer experiments indicate that crocodiles detect both air-borne and water-soluble chemicals and use their olfactory system for hunting. Crocodile_sentence_89

When above water, crocodiles enhance their ability to detect volatile odorants by gular pumping, a rhythmic movement of the floor of the pharynx. Crocodile_sentence_90

Crocodiles close their nostrils when submerged, so olfaction underwater is unlikely. Crocodile_sentence_91

Underwater food detection is presumably gustatory and tactile. Crocodile_sentence_92

Hearing Crocodile_section_9

Crocodiles can hear well; their tympanic membranes are concealed by flat flaps that may be raised or lowered by muscles. Crocodile_sentence_93

Touch Crocodile_section_10

Cranial: The upper and lower jaws are covered with sensory pits, visible as small, black speckles on the skin, the crocodilian version of the lateral line organs seen in fish and many amphibians, though arising from a completely different origin. Crocodile_sentence_94

These pigmented nodules encase bundles of nerve fibers innervated beneath by branches of the trigeminal nerve. Crocodile_sentence_95

They respond to the slightest disturbance in surface water, detecting vibrations and small pressure changes as small as a single drop. Crocodile_sentence_96

This makes it possible for crocodiles to detect prey, danger and intruders, even in total darkness. Crocodile_sentence_97

These sense organs are known as domed pressure receptors (DPRs). Crocodile_sentence_98

Post-Cranial: While alligators and caimans have DPRs only on their jaws, crocodiles have similar organs on almost every scale on their bodies. Crocodile_sentence_99

The function of the DPRs on the jaws is clear; to catch prey, but it is still not clear what the function is of the organs on the rest of the body. Crocodile_sentence_100

The receptors flatten when exposed to increased osmotic pressure, such as that experienced when swimming in sea water hyperosmotic to the body fluids. Crocodile_sentence_101

When contact between the integument and the surrounding sea water solution is blocked, crocodiles are found to lose their ability to discriminate salinities. Crocodile_sentence_102

It has been proposed that the flattening of the sensory organ in hyperosmotic sea water is sensed by the animal as "touch", but interpreted as chemical information about its surroundings. Crocodile_sentence_103

This might be why in alligators they are absent on the rest of the body. Crocodile_sentence_104

Hunting and diet Crocodile_section_11

Crocodiles are ambush predators, waiting for fish or land animals to come close, then rushing out to attack. Crocodile_sentence_105

Crocodiles mostly eat fish, amphibians, crustaceans, molluscs, birds, reptiles, and mammals, and they occasionally cannibalize smaller crocodiles. Crocodile_sentence_106

What a crocodile eats varies greatly with species, size and age. Crocodile_sentence_107

From the mostly fish-eating species, like the slender-snouted and freshwater crocodiles, to the larger species like the Nile crocodile and the saltwater crocodile that prey on large mammals, such as buffalo, deer and wild boar, diet shows great diversity. Crocodile_sentence_108

Diet is also greatly affected by the size and age of the individual within the same species. Crocodile_sentence_109

All young crocodiles hunt mostly invertebrates and small fish, gradually moving on to larger prey. Crocodile_sentence_110

Being ectothermic (cold-blooded) predators, they have a very slow metabolism, so they can survive long periods without food. Crocodile_sentence_111

Despite their appearance of being slow, crocodiles have a very fast strike and are top predators in their environment, and various species have been observed attacking and killing other predators such as sharks and big cats. Crocodile_sentence_112

Crocodiles are also known to be aggressive scavengers who feed upon carrion and steal from other predators. Crocodile_sentence_113

Evidence suggests that crocodiles also feed upon fruits, based on the discovery of seeds in stools and stomachs from many subjects as well as accounts of them feeding. Crocodile_sentence_114

Crocodiles have the most acidic stomach of any vertebrate. Crocodile_sentence_115

They can easily digest bones, hooves and horns. Crocodile_sentence_116

The BBC TV reported that a Nile crocodile that has lurked a long time underwater to catch prey builds up a large oxygen debt. Crocodile_sentence_117

When it has caught and eaten that prey, it closes its right aortic arch and uses its left aortic arch to flush blood loaded with carbon dioxide from its muscles directly to its stomach; the resulting excess acidity in its blood supply makes it much easier for the stomach lining to secrete more stomach acid to quickly dissolve bulks of swallowed prey flesh and bone. Crocodile_sentence_118

Many large crocodilians swallow stones (called gastroliths or stomach stones), which may act as ballast to balance their bodies or assist in crushing food, similar to grit ingested by birds. Crocodile_sentence_119

Herodotus claimed that Nile crocodiles had a symbiotic relationship with certain birds, such as the Egyptian plover, which enter the crocodile's mouth and pick leeches feeding on the crocodile's blood; with no evidence of this interaction actually occurring in any crocodile species, it is most likely mythical or allegorical fiction. Crocodile_sentence_120

Bite Crocodile_section_12

Since they feed by grabbing and holding onto their prey, they have evolved sharp teeth for piercing and holding onto flesh, and powerful muscles to close the jaws and hold them shut. Crocodile_sentence_121

The teeth are not well-suited to tearing flesh off of large prey items as are the dentition and claws of many mammalian carnivores, the hooked bills and talons of raptorial birds, or the serrated teeth of sharks. Crocodile_sentence_122

However, this is an advantage rather than a disadvantage to the crocodile since the properties of the teeth allow it to hold onto prey with the least possibility of the prey animal escaping. Crocodile_sentence_123

Cutting teeth, combined with the exceptionally high bite force, would pass through flesh easily enough to leave an escape opportunity for prey. Crocodile_sentence_124

The jaws can bite down with immense force, by far the strongest bite of any animal. Crocodile_sentence_125

The force of a large crocodile's bite is more than 5,000 lbf (22,000 N), which was measured in a 5.5 m (18 ft) Nile crocodile, in the field; comparing to 335 lbf (1,490 N) for a Rottweiler, 800 lbf (3,600 N) for a hyena, 2,200 lbf (9,800 N) for an American alligator, and 4,095 lbf (18,220 N) for the largest confirmed great white shark. Crocodile_sentence_126

A 5.2 m (17 ft) long saltwater crocodile has been confirmed as having the strongest bite force ever recorded for an animal in a laboratory setting. Crocodile_sentence_127

It was able to apply a bite force value of 3,700 lbf (16,000 N), and thus surpassed the previous record of 2,125 lbf (9,450 N) made by a 3.9 m (13 ft) long American alligator. Crocodile_sentence_128

Taking the measurements of several 5.2 m (17 ft) crocodiles as reference, the bite forces of 6-m individuals were estimated at 7,700 lbf (34,000 N). Crocodile_sentence_129

The study, led by Dr. Gregory M. Erickson, also shed light on the larger, extinct species of crocodilians. Crocodile_sentence_130

Since crocodile anatomy has changed only slightly over the last 80 million years, current data on modern crocodilians can be used to estimate the bite force of extinct species. Crocodile_sentence_131

An 11-to-12-metre (36–39 ft) Deinosuchus would apply a force of 23,100 lbf (103,000 N), nearly twice that of the latest, higher bite force estimations of Tyrannosaurus (12,814 lbf (57,000 N)). Crocodile_sentence_132

The extraordinary bite of crocodilians is a result of their anatomy. Crocodile_sentence_133

The space for the jaw muscle in the skull is very large, which is easily visible from the outside as a bulge at each side. Crocodile_sentence_134

The muscle is so stiff, it is almost as hard as bone to touch, as if it were the continuum of the skull. Crocodile_sentence_135

Another trait is that most of the muscle in a crocodile's jaw is arranged for clamping down. Crocodile_sentence_136

Despite the strong muscles to close the jaw, crocodiles have extremely small and weak muscles to open the jaw. Crocodile_sentence_137

Crocodiles can thus be subdued for study or transport by taping their jaws or holding their jaws shut with large rubber bands cut from automobile inner tubes. Crocodile_sentence_138

Locomotion Crocodile_section_13

Crocodiles can move quickly over short distances, even out of water. Crocodile_sentence_139

The land speed record for a crocodile is 17 km/h (11 mph) measured in a galloping Australian freshwater crocodile. Crocodile_sentence_140

Maximum speed varies between species. Crocodile_sentence_141

Some species can gallop, including Cuban crocodiles, Johnston's crocodiles, New Guinea crocodiles, African dwarf crocodiles, and even small Nile crocodiles. Crocodile_sentence_142

The fastest means by which most species can move is a "belly run", in which the body moves in a snake-like (sinusoidal) fashion, limbs splayed out to either side paddling away frantically while the tail whips to and fro. Crocodile_sentence_143

Crocodiles can reach speeds of 10–11 km/h (6–7 mph) when they "belly run", and often faster if slipping down muddy riverbanks. Crocodile_sentence_144

When a crocodile walks quickly, it holds its legs in a straighter and more upright position under its body, which is called the "high walk". Crocodile_sentence_145

This walk allows a speed of up to 5 km/h. Crocodile_sentence_146

Crocodiles may possess a homing instinct. Crocodile_sentence_147

In northern Australia, three rogue saltwater crocodiles were relocated 400 km (249 mi) by helicopter, but returned to their original locations within three weeks, based on data obtained from tracking devices attached to them. Crocodile_sentence_148

Longevity Crocodile_section_14

Measuring crocodile age is unreliable, although several techniques are used to derive a reasonable guess. Crocodile_sentence_149

The most common method is to measure lamellar growth rings in bones and teeth—each ring corresponds to a change in growth rate which typically occurs once a year between dry and wet seasons. Crocodile_sentence_150

Bearing these inaccuracies in mind, it can be safely said that all crocodile species have an average lifespan of at least 30–40 years, and in the case of larger species an average of 60–70 years. Crocodile_sentence_151

The oldest crocodiles appear to be the largest species. Crocodile_sentence_152

C. Crocodile_sentence_153 porosus is estimated to live around 70 years on average, with limited evidence of some individuals exceeding 100 years. Crocodile_sentence_154

In captivity, some individuals are claimed to have lived for over a century. Crocodile_sentence_155

A male crocodile lived to an estimated age of 110–115 years in a Russian zoo in Yekaterinburg. Crocodile_sentence_156

Named Kolya, he joined the zoo around 1913 to 1915, fully grown, after touring in an animal show, and lived until 1995. Crocodile_sentence_157

A male freshwater crocodile lived to an estimated age of 120–140 years at the Australia Zoo. Crocodile_sentence_158

Known affectionately as "Mr. Freshie", he was rescued around 1970 by Bob Irwin and Steve Irwin, after being shot twice by hunters and losing an eye as a result, and lived until 2010. Crocodile_sentence_159

Crocworld Conservation Centre, in Scottburgh, South Africa, claims to have a male Nile crocodile that was born in 1900. Crocodile_sentence_160

Named Henry, the crocodile is said to have lived in Botswana along the Okavango River, according to centre director Martin Rodrigues. Crocodile_sentence_161

Social behaviour and vocalization Crocodile_section_15

Crocodiles are the most social of reptiles. Crocodile_sentence_162

Even though they do not form social groups, many species congregate in certain sections of rivers, tolerating each other at times of feeding and basking. Crocodile_sentence_163

Most species are not highly territorial, with the exception of the saltwater crocodile, which is a highly territorial and aggressive species: a mature, male saltwater crocodile will not tolerate any other males at any time of the year, but most other species are more flexible. Crocodile_sentence_164

There is a certain form of hierarchy in crocodiles: the largest and heaviest males are at the top, having access to the best basking site, while females are priority during a group feeding of a big kill or carcass. Crocodile_sentence_165

A good example of the hierarchy in crocodiles would be the case of the Nile crocodile. Crocodile_sentence_166

This species clearly displays all of these behaviours. Crocodile_sentence_167

Studies in this area are not thorough, however, and many species are yet to be studied in greater detail. Crocodile_sentence_168

Mugger crocodiles are also known to show toleration in group feedings and tend to congregate in certain areas. Crocodile_sentence_169

However, males of all species are aggressive towards each other during mating season, to gain access to females. Crocodile_sentence_170

Crocodiles are also the most vocal of all reptiles, producing a wide variety of sounds during various situations and conditions, depending on species, age, size and sex. Crocodile_sentence_171

Depending on the context, some species can communicate over 20 different messages through vocalizations alone. Crocodile_sentence_172

Some of these vocalizations are made during social communication, especially during territorial displays towards the same sex and courtship with the opposite sex; the common concern being reproduction. Crocodile_sentence_173

Therefore most conspecific vocalization is made during the breeding season, with the exception being year-round territorial behaviour in some species and quarrels during feeding. Crocodile_sentence_174

Crocodiles also produce different distress calls and in aggressive displays to their own kind and other animals; notably other predators during interspecific predatory confrontations over carcasses and terrestrial kills. Crocodile_sentence_175

Specific vocalisations include — Crocodile_sentence_176

Crocodile_unordered_list_0

  • Chirp: When about to hatch, the young make a "peeping" noise, which encourages the female to excavate the nest. The female then gathers the hatchlings in her mouth and transports them to the water, where they remain in a group for several months, protected by the femaleCrocodile_item_0_0
  • Distress call: A high-pitched call used mostly by younger animals to alert other crocodiles to imminent danger or an animal being attacked.Crocodile_item_0_1
  • Threat call: A hissing sound that has also been described as a coughing noise.Crocodile_item_0_2
  • Hatching call: Emitted by a female when breeding to alert other crocodiles that she has laid eggs in her nest.Crocodile_item_0_3
  • Bellowing: Male crocodiles are especially vociferous. Bellowing choruses occur most often in the spring when breeding groups congregate, but can occur at any time of year. To bellow, males noticeably inflate as they raise the tail and head out of water, slowly waving the tail back and forth. They then puff out the throat and with a closed mouth, begin to vibrate air. Just before bellowing, males project an infrasonic signal at about 10 Hz through the water, which vibrates the ground and nearby objects. These low-frequency vibrations travel great distances through both air and water to advertise the male's presence and are so powerful they result in the water's appearing to "dance".Crocodile_item_0_4

Reproduction Crocodile_section_16

Crocodiles lay eggs, which are laid in either holes or mound nests, depending on species. Crocodile_sentence_177

A hole nest is usually excavated in sand and a mound nest is usually constructed out of vegetation. Crocodile_sentence_178

Nesting periods range from a few weeks up to six months. Crocodile_sentence_179

Courtship takes place in a series of behavioural interactions that include a variety of snout rubbing and submissive display that can take a long time. Crocodile_sentence_180

Mating always takes place in water, where the pair can be observed mating several times. Crocodile_sentence_181

Females can build or dig several trial nests which appear incomplete and abandoned later. Crocodile_sentence_182

Egg-laying usually takes place at night and about 30–40 minutes. Crocodile_sentence_183

Females are highly protective of their nests and young. Crocodile_sentence_184

The eggs are hard shelled, but translucent at the time of egg-laying. Crocodile_sentence_185

Depending on the species of crocodile, 7 to 95 eggs are laid. Crocodile_sentence_186

Crocodile embryos do not have sex chromosomes, and unlike humans, sex is not determined genetically. Crocodile_sentence_187

Sex is determined by temperature, where at 30 °C (86 °F) or less most hatchlings are females and at 31 °C (88 °F), offspring are of both sexes. Crocodile_sentence_188

A temperature of 32 to 33 °C (90 to 91 °F) gives mostly males whereas above 33 °C (91 °F) in some species continues to give males, but in other species resulting in females, which are sometimes called high-temperature females. Crocodile_sentence_189

Temperature also affects growth and survival rate of the young, which may explain the sexual dimorphism in crocodiles. Crocodile_sentence_190

The average incubation period is around 80 days, and also is dependent on temperature and species that usually ranges from 65 to 95 days. Crocodile_sentence_191

The eggshell structure is very conservative through evolution but there are enough changes to tell different species apart by their eggshell microstructure. Crocodile_sentence_192

Scutes may play a role in calcium storage for eggshell formation. Crocodile_sentence_193

At the time of hatching, the young start calling within the eggs. Crocodile_sentence_194

They have an egg-tooth at the tip of their snouts, which is developed from the skin, and that helps them pierce out of the shell. Crocodile_sentence_195

Hearing the calls, the female usually excavates the nest and sometimes takes the unhatched eggs in her mouth, slowly rolling the eggs to help the process. Crocodile_sentence_196

The young is usually carried to the water in the mouth. Crocodile_sentence_197

She would then introduce her hatchlings to the water and even feed them. Crocodile_sentence_198

The mother would then take care of her young for over a year before the next mating season. Crocodile_sentence_199

In the absence of the mother crocodile, the father would act in her place to take care of the young. Crocodile_sentence_200

However, even with a sophisticated parental nurturing, young crocodiles have a very high mortality rate due to their vulnerability to predation. Crocodile_sentence_201

A group of hatchlings is called a pod or crèche and may be protected for months. Crocodile_sentence_202

Cognition Crocodile_section_17

Crocodiles possess some advanced cognitive abilities. Crocodile_sentence_203

They can observe and use patterns of prey behaviour, such as when prey come to the river to drink at the same time each day. Crocodile_sentence_204

Vladimir Dinets of the University of Tennessee, observed that crocodiles use twigs as bait for birds looking for nesting material. Crocodile_sentence_205

They place sticks on their snouts and partly submerge themselves. Crocodile_sentence_206

When the birds swooped in to get the sticks, the crocodiles then catch the birds. Crocodile_sentence_207

Crocodiles only do this in spring nesting seasons of the birds, when there is high demand for sticks to be used for building nests. Crocodile_sentence_208

Vladimir also discovered other similar observations from various scientists, some dating back to the 19th century. Crocodile_sentence_209

Aside from using sticks, crocodiles are also capable of cooperative hunting. Crocodile_sentence_210

Large numbers of crocodiles swim in circles to trap fish and take turns snatching them. Crocodile_sentence_211

In hunting larger prey, crocodiles swarm in, with one holding the prey down as the others rip it apart. Crocodile_sentence_212

According to a 2015 study, crocodiles engage in all three main types of play behaviour recorded in animals: locomotor play, play with objects and social play. Crocodile_sentence_213

Play with objects is reported most often, but locomotor play such as repeatedly sliding down slopes, and social play such as riding on the backs of other crocodiles is also reported. Crocodile_sentence_214

This behaviour was exhibited with conspecifics and mammals and is apparently not uncommon, though has been difficult to observe and interpret in the past due to obvious dangers of interacting with large carnivores. Crocodile_sentence_215

Taxonomy and phylogeny Crocodile_section_18

Most species are grouped into the genus Crocodylus. Crocodile_sentence_216

The other extant genus, Osteolaemus, is monotypic (as is Mecistops, if recognized). Crocodile_sentence_217

Crocodile_unordered_list_1

Phylogeny Crocodile_section_19

The cladogram below follows the topology from a 2012 analysis of morphological traits by Christopher A. Brochu and Glenn W. Storrs. Crocodile_sentence_218

Many extinct species of Crocodylus might represent different genera. Crocodile_sentence_219

"Crocodylus" pigotti, for example, was placed in the newly erected genus Brochuchus in 2013. Crocodile_sentence_220

C. suchus was not included because its morphological codings were identical to those of C. niloticus. Crocodile_sentence_221

However, the authors suggested that the lack of differences was due to limited specimen sampling, and considered the two species to be distinct. Crocodile_sentence_222

This analysis found weak support for the clade Osteolaeminae. Crocodile_sentence_223

Brochu named Osteolaeminae in 2003 as a subfamily of Crocodylidae separate from Crocodylinae, but the group has since been classified within Crocodylinae. Crocodile_sentence_224

It includes the living genus Osteolaemus as well as the extinct species Voay robustus and Rimasuchus lloydi. Crocodile_sentence_225

A 2013 analysis by Jack L. Conrad, Kirsten Jenkins, Thomas Lehmann, and others did not support Osteolaeminae as a true clade but rather a paraphyletic group consisting of two smaller clades. Crocodile_sentence_226

They informally called these clades "osteolaemins" and "mecistopins". Crocodile_sentence_227

"Osteolaemins" include Osteolaemus, Voay, Rimasuchus, and Brochuchus and "mecistopins" include Mecistops and Euthecodon. Crocodile_sentence_228

Relationship with humans Crocodile_section_20

Danger to humans Crocodile_section_21

Main article: Crocodile attacks Crocodile_sentence_229

The larger species of crocodiles are very dangerous to humans, mainly because of their ability to strike before the person can react. Crocodile_sentence_230

The saltwater crocodile and Nile crocodile are the most dangerous, killing hundreds of people each year in parts of Southeast Asia and Africa. Crocodile_sentence_231

The mugger crocodile and American crocodile are also dangerous to humans. Crocodile_sentence_232

Crocodile products Crocodile_section_22

Further information: Crocodile farm and Crocodile skin Crocodile_sentence_233

Crocodiles are protected in many parts of the world, but are also farmed commercially. Crocodile_sentence_234

Their hides are tanned and used to make leather goods such as shoes and handbags; crocodile meat is also considered a delicacy. Crocodile_sentence_235

The most commonly farmed species are the saltwater and Nile crocodiles, while a hybrid of the saltwater and the rare Siamese crocodile is also bred in Asian farms. Crocodile_sentence_236

Farming has resulted in an increase in the saltwater crocodile population in Australia, as eggs are usually harvested from the wild, so landowners have an incentive to conserve their habitat. Crocodile_sentence_237

Crocodile leather can be made into goods such as wallets, briefcases, purses, handbags, belts, hats, and shoes. Crocodile_sentence_238

Crocodile oil has been used for various purposes. Crocodile_sentence_239

Crocodiles were eaten by Vietnamese while they were taboo and off limits for Chinese. Crocodile_sentence_240

Vietnamese women who married Chinese men adopted the Chinese taboo. Crocodile_sentence_241

Crocodile meat is consumed in some countries, such as Australia, Ethiopia, Thailand, South Africa, China and also Cuba (in pickled form). Crocodile_sentence_242

It is also occasionally eaten as an "exotic" delicacy in the western world. Crocodile_sentence_243

Cuts of meat include backstrap and tail fillet. Crocodile_sentence_244

Due to high demand for crocodile products, TRAFFIC states that 1,418,487 Nile Crocodile skins were exported from Africa between 2006 and 2015. Crocodile_sentence_245

In religion Crocodile_section_23

Crocodiles have appeared in various forms in religions across the world. Crocodile_sentence_246

Ancient Egypt had Sobek, the crocodile-headed god, with his cult-city Crocodilopolis, as well as Taweret, the goddess of childbirth and fertility, with the back and tail of a crocodile. Crocodile_sentence_247

The Jukun shrine in the Wukari Federation, Nigeria is dedicated to crocodiles in thanks for their aid during migration. Crocodile_sentence_248

In Madagascar various peoples such as the Sakalava and Antandroy see crocodiles as ancestor spirits and under local fady often offer them food; in the case of the latter at least a crocodile features prominently as an ancestor deity. Crocodile_sentence_249

Crocodiles appear in different forms in Hinduism. Crocodile_sentence_250

Varuna, a Vedic and Hindu god, rides a part-crocodile makara; his consort Varuni rides a crocodile. Crocodile_sentence_251

Similarly the goddess personifications of the Ganga and Yamuna rivers are often depicted as riding crocodiles. Crocodile_sentence_252

Also in India, in Goa, crocodile worship is practised, including the annual Mannge Thapnee ceremony. Crocodile_sentence_253

In Latin America, Cipactli was the giant earth crocodile of the Aztec and other Nahua peoples. Crocodile_sentence_254

Crocodile tears Crocodile_section_24

Main article: Crocodile tears Crocodile_sentence_255

The term "crocodile tears" (and equivalents in other languages) refers to a false, insincere display of emotion, such as a hypocrite crying fake tears of grief. Crocodile_sentence_256

It is derived from an ancient anecdote that crocodiles weep in order to lure their prey, or that they cry for the victims they are eating, first told in the Bibliotheca by Photios I of Constantinople. Crocodile_sentence_257

The story is repeated in bestiaries such as De bestiis et aliis rebus. Crocodile_sentence_258

This tale was first spread widely in English in the stories of the Travels of Sir John Mandeville in the 14th century, and appears in several of Shakespeare's plays. Crocodile_sentence_259

In fact, crocodiles can and do generate tears, but they do not actually cry. Crocodile_sentence_260

The Surabaya Shark and Crocodile Crocodile_section_25

The name of Surabaya, Indonesia, is locally believed to be derived from the words "suro" (shark) and "boyo" (crocodile), two creatures which, in a local myth, fought each other in order to gain the title of "the strongest and most powerful animal" in the area. Crocodile_sentence_261

It was said that the two powerful animals agreed for a truce and set boundaries; that the shark's domain would be in the sea while the crocodile's domain would be on the land. Crocodile_sentence_262

However one day the shark swam into the river estuary to hunt, this angered the crocodile, who declared it his territory. Crocodile_sentence_263

The Shark argued that the river was a water-realm which meant that it was shark territory, while the crocodile argued that the river flowed deep inland, so it was therefore crocodile territory. Crocodile_sentence_264

A ferocious fight resumed as the two animals bit each other. Crocodile_sentence_265

Finally the shark was badly bitten and fled to the open sea, and the crocodile finally ruled the estuarine area that today is the city. Crocodile_sentence_266

Another source alludes to a Jayabaya prophecy—a 12th-century psychic king of Kediri Kingdom—as he foresaw a fight between a giant white shark and a giant white crocodile taking place in the area, which is sometimes interpreted as a foretelling of the Mongol invasion of Java, a major conflict between the forces of the Kublai Khan, Mongol ruler of China, and those of Raden Wijaya's Majapahit in 1293. Crocodile_sentence_267

The two animals are now used as the city's symbol, with the two facing and circling each other, as depicted in a statue appropriately located near the entrance to the city zoo (see photo on the Surabaya page). Crocodile_sentence_268

Crocodile (walking) Crocodile_section_26

In the UK, a row of schoolchildren walking in pairs, or two by two is known as 'crocodile'. Crocodile_sentence_269

See also Crocodile_section_27

Credits to the contents of this page go to the authors of the corresponding Wikipedia page: en.wikipedia.org/wiki/Crocodile.