Crocodiles are reptiles belonging to the family Crocodylidae (sometimes classified instead as the subfamily Crocodylinae). The term is however also often used to mean all crocodilians, i.e. all animals belonging to the order Crocodilia which includes alligators, caimans and gharials (gavials) as well. A more correct way of referring to these animals is to say Crocodiles when referring only to the family Crocodylidae and crocodilians when referring to order Crocodilia.
Crocodiles are large aquatic mammals that can be found throughout the tropical world. Crocodiles have been around for 200 million years and changed very little during this time. They survived the mass extinction that killed the dinosaurs and are today found in Africa, Asia, Australia and the Americas. Crocodiles are primarily found in freshwater but some species can also be found in brackish water. The saltwater crocodile (Crocodylus porosus) can wander into marine environments but is also usually found in fresh or brackish water.
Different crocodile species differs in length from 1 m / 3.3 ft to almost 9 m / 30 ft. The smallest crocodile species are the ones found in the genera Palaeosuchus and Osteolaemus which grow to 100-150 cm / 3.3-5 ft in length. The largest species of crocodile in the world is the Saltwater crocodile. The largest recorded specimen of this species was 8.6 m (28 ft) and weighed 1,352 kg (2,980 lbs). That is however a rare case and 5 m / 16 ft and 1,200 kg (2,600 lb) is to be considered more normal, although some specimens do grow considerably larger as the earlier mentioned example demonstrates. The saltwater crocodile is also the most well known of all crocodiles and when people think about crocodiles they usually think of Saltwater or Nile crocodiles (Crocodylus niloticus). It is unknown how old crocodiles can become but we do know that they can exceed 100 years of age. A freshwater crocodile in captivity in Australia is estimated to be 130 years old.
Crocodiles are ambush hunters that eat fish, birds, reptiles and mammals as well as invertebrates. Large crocodiles are even known to eat sharks, and they will certainly not hesitate to prey on smaller members of their own species. The diet varies a little between species but all crocodiles are predatory. They are “cold blooded” like all reptiles which allow them to survive long periods without food. This means that they seldom need to actively hunt and instead can be opportunistic. Large crocodile species swallow stones and the exact purpose of this remains a mystery. Some believe it is to help digest the food while others believe they are used as ballast to help the crocodile keep its balance.
Most crocodile species belong to the genus Crocodylus but some species are found outside this genus. The taxonomy of crocodiles is under review and changes might be made to this classification soon. One such change is that the Slender-snouted crocodile might be moved to its own genus, Mecistops,due to findings discovered through DNA analysis.
+ Crocodylus acutus, American Crocodile
+ Crocodylus cataphractus, Slender-snouted Crocodile
+ Crocodylus intermedius, Orinoco Crocodile
+ Crocodylus johnsoni, Freshwater Crocodile
+ Crocodylus mindorensis, Philippine Crocodile
+ Crocodylus moreletii, Morelet's Crocodile or Mexican Crocodile
+ Crocodylus niloticus, Nile Crocodile or African 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
+ Osteolaemus tetraspis, Dwarf Crocodile
Genus Asiatosuchus (no living species)
Genus Euthecodon (no living species)
Genus Rimasuchus (no living species)
Genus Voay (no living species)
Crocodiles lay eggs that are buried in mounds created and guarded by the female. The eggs lack sex deciding chromosomes and the sex of the offspring is instead decided by the temperature in the mound. Males develop around 31.6 °C. Females develop at lower and higher temperatures. The temperature also affects how long it takes for the eggs to hatch (the time span also varies from species to species) hatching will usually take place after roughly 80 days. The female crocodile will take the baby crocodiles in her mouth and carry them to water. This gave birth to a myth that female crocodiles will eat their own young directly from the nest. She will also protect the baby crocs from other crocs that might eat them by defending her territory.
Many crocodile populations around the world are endangered and protected. A lot of conservation effort is put in to preserving these populations and some encouraging results have been achieved in some areas. Crocodile farming have had positive effects as much of the young crocodiles are collected as eggs from the wild creating an economic incentive for land owners to make sure that their land is good crocodile habitat.
Crocodiles are among the few animals that hunt humans for food and some species can be dangerous. The Nile crocodile and Saltwater crocodile will attempt to prey on humans and are responsible for 100s of deaths each year in Africa and South East Asia. The Mugger crocodile (Crocodylus palustris) can also be dangerous for humans.