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Crocodile

2007 Schools Wikipedia Selection. Related subjects: Insects, Reptiles and
Fish

                iCrocodiles
   Nile Crocodile
   Nile Crocodile
         Scientific classification

   Kingdom: Animalia
   Phylum:  Chordata
   Class:   Sauropsida
   Order:   Crocodilia
   Family:  Crocodylidae
            Cuvier, 1807

                                   Genera

     * Mecistops
     * Crocodylus
     * Osteolaemus

   See full taxonomy.

   A crocodile is any species belonging to the family Crocodylidae
   (sometimes classified instead as the subfamily Crocodylinae). The term
   can also be used more loosely to include all members of the order
   Crocodilia: i.e. the true crocodiles, the alligators and caimans
   (family Alligatoridae) and the gharials (family Gavialidae). The
   crocodiles, colloquially called crocs, are large aquatic reptiles that
   live throughout the Tropics in Africa, Asia, the Americas and
   Australia. Crocodiles tend to congregate in freshwater habitats like
   rivers and lakes and wetlands and sometimes in brackish water. Some
   species, notably the Saltwater Crocodile of Australia, Southeast Asia
   and the Pacific islands often lives along the coastal areas as its name
   implies. It is also known to venture far out to sea. They mostly feed
   on a wide variety of vertebrates like fish, reptiles, and mammals,
   sometimes with invertebrates like mollusks and crustaceans, depending
   on species. They are an ancient lineage, and are believed to have
   changed little since the time of the dinosaurs.

Appearance and physical traits

   Crocodiles are the most advanced of all reptiles despite their
   prehistoric look. Unlike other reptiles they have a four-chambered
   heart, diaphragm and cerebral cortex. Their external morphology on the
   other hand is a sign of their aquatic and predatory lifestyle. A
   crocodile’s physical traits allow it to be a successful predator. They
   have a streamlined body that enables them to swim faster. They also
   tuck their feet to their sides while swimming, which makes the animal
   even faster, by decreasing the amount of water resistance. They have
   webbed feet, although not used to propel the animal through the water,
   this allows it to make fast turns and sudden moves in the water or
   initiate swimming. Webbed feet are an advantage in shallower water
   where the animals sometimes move around by walking.

   Crocodiles are very fast over short distances, even out of water. They
   have extremely powerful jaws and sharp teeth for tearing flesh, but
   cannot open their mouth if it is held closed, hence there are stories
   of people escaping from the long-snouted Nile Crocodile by holding its
   jaws shut. Indeed, zoologists will often subdue crocodiles for study or
   transport by taping their jaws or holding their jaws shut with large
   rubber bands cut from automobile inner tubes. All large crocodiles also
   have sharp welters and powerful claws. They have limited lateral
   movement in their neck, so on land one can find protection by getting
   even a small tree between the crocodile's jaws and oneself.

Age

   There is currently no reliable way of measuring crocodile age, although
   several techniques can be used to derive a reasonable guess. 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. Bearing these inaccuracies in
   mind, the oldest crocodilians appear to be the largest species. C.
   porosus is estimated to live around 70 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. The news report did not identify the species.
   West African dwarf crocodile from the forests of West and West Central
   Africa
   Enlarge
   West African dwarf crocodile from the forests of West and West Central
   Africa

Size

   Large Crocodile in captivity in Australia
   Enlarge
   Large Crocodile in captivity in Australia

   Size greatly varies between species. From the exceptionally small dwarf
   crocodile to the enormous saltwater crocodile, they range in all sorts
   of sizes. Large species can often reach huge sizes over 5 or 6 metres
   and weigh well over 1200kg. Despite their large adult size, crocodiles
   start their life interestingly small. Crocodiles when first hatched are
   around 20 cm. Sizes vary depending on the season and health and blood
   composition of the mother. The largest species of crocodile, also
   Earth's largest reptile, is the Saltwater Crocodile, found in northern
   Australia and throughout South-east Asia. According to some scientists,
   there are no truly reliable records of any non-prehistoric crocodiles
   over 8.64m.

   In the town of Normanton, Queensland, Australia, there is a fibreglass
   mould of a crocodile called "Krys the Croc.," shot in 1958 by Krystina
   Pawloski, who found the animal on a sandbank on the Norman River. There
   is a report of a saltwater crocodile in Australia that was 8.2 m long.
   There is also a skull of a salt water crocodile from Orissa, India that
   is very large and the animal is estimated to have been 6.4 to 7 m long.

   The other two larger certifiable records of complete crocodile are both
   of 6.2 m crocodiles. The first crocodile was shot in the Mary River in
   the Northern Territory of Australia in 1974 by poachers and measured by
   wildlife rangers. The second crocodile was killed in 1983 in the Fly
   River, Papua New Guinea. In this latter crocodile it was actually the
   skin that was measured by zoologist Jerome Montague, and as skins are
   known to underestimate the size of the actual animal, it is possible
   this crocodile was at least another 10 cm longer.

   The largest crocodile ever held in captivity is an Estuarine/Siamese
   hybrid named Yai ( Thai: ใหญ่, meaning big) (born 10 June, 1972) at the
   famous Samutprakarn Crocodile Farm and Zoo, Thailand. He measures 6 m.
   in length and weighs 1,114.27 kg.

   Another huge captive crocodile was a saltie named Gomek. Gomek was
   captured by George Craig in Papua New Guinea and sold to St. Augustine
   Alligator Farm in Florida. Although George captured an even larger
   crocodile with Gomek, it is uncertain whether this animal is still
   alive on Green Island in Queensland where George Craig now lives. After
   many years, Gomek died of heart disease in February 1997. By this
   stage, he was a very old crocodile. When he died, he was 5.5 m long -
   as confirmed by St. Augustine Alligator Farm - and probably between 70
   and 80 years old.

   On June 16, 2006, A 7.1m giant saltwater crocodile in Orissa, India was
   crowned the world's largest living crocodile. It lives in Bhitarkanika
   Wildlife Sanctuary and in June 2006, was entered in the Guinness Book
   of World Records.

   Wildlife experts, however, argued that the largest crocodile so far
   found in the Bhitarkanika was almost 7.62 m which could be traced from
   the skull preserved by the Kanika Royal Family. The crocodile, probably
   was shot dead near Dhamara during 1926 and later its skull was
   preserved by the then Kanika King. The crocodile experts said as per
   the parameters, the crocodile would be about 7.62 m since the size of
   the skull was measured one seventh of the total length of the body.

Biology and Behaviour

   Crocodiles are ambush hunters, waiting for fish or land animals to come
   close, then rushing out to attack. As cold-blooded predators, they can
   survive long periods without food, and rarely need to actively go
   hunting. The crocodile's bite strength is up to 3,000 pounds per square
   inch, comparing to just 100 psi for a labrador retriever or 350 psi for
   a large shark. Despite their slow appearance, crocodiles are the top
   predators in their environment, and various species have been observed
   attacking and killing big cats like lions , large ungulates and even
   sharks. A famous exception is the Egyptian Plover which is said to
   enjoy a symbiotic relationship with the crocodile. According to
   unauthenticated reports, the plover feeds on parasites that infest the
   crocodile's mouth and the reptile will open its jaws and allow the bird
   to enter to clean out the mouth.
   Crocodile farm in Mexico
   Enlarge
   Crocodile farm in Mexico

   Crocodiles eat fish, birds, mammals and occasionally smaller
   crocodiles. Wild crocodiles are protected in many parts of the world,
   but they also are farmed commercially. Their hide is tanned and used to
   make leather goods such as shoes and handbags, whilst crocodile meat is
   also considered a delicacy in many parts of the world. 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. 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 crocodile
   habitat. Crocodiles are more closely related to birds and dinosaurs
   than to most animals classified as reptiles, the three being included
   in the group Archosauria ('ruling reptiles'). See Crocodilia for more
   information.

Danger to humans

   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 are the leading cause of
   animal related deaths as of 2001.

Crocodile blood

   Scientists in the United States have isolated a powerful agent in
   crocodile blood ( crocodillin) which could help conquer human
   infections immune to standard antibiotics. The discovery was made
   thanks to the curiosity of Jill Fullerton-Smith, a BBC science producer
   filming a documentary on salt-water crocodiles in Australia.

Crocodile as food

   Crocodile is consumed in some countries such as Australia, Thailand,
   South Africa and also Cuba (in pickled form). The meat is white and its
   nutritional composition compares favourably with that of more
   traditional meats. It does tend to have a slightly higher cholesterol
   level than other meats. Crocodile meat has a delicate flavour and its
   taste can be complemented, if not masked, by the use of powerful
   marinades. Choice cuts of meat include backstrap and tail fillet.

Trivia

     * The crocodile gets its name from the Greeks who observed them in
       the Nile river. The Greeks called them krokodilos, a compound word
       from kroke, which means "pebbles" and drilos, which means "worm".
       To the Greeks, this "worm of the stones" was so named because of
       the crocodiles habit of basking in the sun on gravel-covered river
       banks.

     * Petsuchos was the name given by the Greeks to the live crocodile at
       Crocodilopolis in Ancient Egypt, which was worshipped as a
       manifestation of the Egyptian god Sobek; the deification of
       crocodiles.

     * Crocodile embryos do not have sex chromosomes, and unlike humans
       sex is not determined genetically. Sex is determined by
       temperature, with males produced at around 31.6 degrees celsius,
       and females produced at slightly lower and higher temperatures. The
       average incubation period is around 80 days, and also is dependent
       upon temperature.

     * Many of the extinct crocodiles were herbivorous.

Taxonomy of the Crocodylidae

   Crocodile farming in Australia.
   Enlarge
   Crocodile farming in Australia.
   Slender-snouted Crocodile, Crocodylus cataphractus
   Enlarge
   Slender-snouted Crocodile, Crocodylus cataphractus
   A bask of crocodiles
   Enlarge
   A bask of crocodiles
   American Crocodlile. Photo taken at La Manzanilla, Jalisco, Mexico
   Enlarge
   American Crocodlile. Photo taken at La Manzanilla, Jalisco, Mexico

   Most species are grouped into the genus Crocodylus. The two other
   living genera of this family are both monotypic: Osteolaemus and
   Tomistoma.
     * FAMILY CROCODYLIDAE
          + Subfamily Mekosuchinae (extinct)
          + Subfamily Crocodylinae
               o Genus Euthecodon (extinct)
               o Genus Osteolaemus
                    # Dwarf Crocodile, Osteolaemus tetraspis (there has
                      been some controversy whether or not this is
                      actually two species; current thinking is that there
                      is one species with 2 subspecies: O. tetraspis
                      tetraspis & O. t. osborni)
               o Genus Crocodylus
                    # Crocodylus acutus , American Crocodile
                    # Crocodylus cataphractus , Slender-snouted Crocodile
                      (Recent DNA studies suggest that this species may
                      actually be more basal than Crocodylus, and belong
                      in its own genus, Mecistops)
                    # Crocodylus intermedius , Orinoco Crocodile
                    # Crocodylus johnstoni, Freshwater Crocodile
                    # Crocodylus mindorensis, Philippine Crocodile
                    # Crocodylus moreletii , Morelet's Crocodile or
                      Mexican Crocodile
                    # Crocodylus niloticus, Nile Crocodile or African
                      Crocodile (the subspecies found in Madagascar is
                      sometimes called the Black Crocodile)
                    # Crocodylus novaeguineae, New Guinea Crocodile
                    # Crocodylus palustris, Mugger Crocodile, Marsh
                      Crocodile, or Indian Crocodile
                    # Crocodylus porosus , Saltwater Crocodile or
                      Estuarine Crocodile
                    # Crocodylus rhombifer , Cuban Crocodile
                    # Crocodylus siamensis, Siamese Crocodile
          + Subfamily Tomistominae (recent studies may show that this
            group is actually more closely related to the Gavialidae)
               o Genus Kentisuchus (extinct)
               o Genus Gavialosuchus (extinct)
               o Genus Paratomistoma (extinct)
               o Genus Thecachampsa (extinct)
               o Genus Kentisuchus (extinct)
               o Genus Rhamphosuchus (extinct)
               o Genus Tomistoma
                    # Tomistoma schlegelii, False gharial or Malayan
                      gharial
                    # Tomistoma lusitanica (extinct)
                    # Tomistoma cairense (extinct)

In popular culture

     * In the fictional Peter Pan series by J.M Barrie, a large crocodile
       serves as Captain Hook's worst fear, as it bit his hand off,
       leaving him with his hook. It also ate a clock, and thus ticking
       lets Hook know if the Crocodile is approaching.

   Image:PeterCroc.jpg
     * In the Disney movie The Wild, two abandoned pet crocodiles that
       dwell in the sewer guide the protagonists to the harbour rather
       than eating them.

     * In the Disney movie The Emperor's New Groove and corresponding TV
       shows and sequels, the villain, Yzma, has a pet crocodile that
       lives in a chamber that is accessed by a lever next to another
       lever that accesses her secret lab. Often she comically pulls the
       wrong lever, falling into the pit, and returns with the crocodile
       latched onto her, and she says 'Why do we even have that lever?'.

     * The Cheburashka series of books (by Eduard Uspensky) and animated
       films feature Crocodile Gena as one of the main characters. He
       works in a zoo as a crocodile.

   Retrieved from " http://en.wikipedia.org/wiki/Crocodile"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
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