CROCODILES Crocodylus porosus By Jose Espaa III Characteristics

CROCODILES (Crocodylus porosus) By: Jose España III

Characteristics • Crocodiles are among the largest reptiles in the animal kingdom. Although size varies among each species. • They are covered in rough scaly skin all over their bodies like armor, the exception is the underbelly which is soft which makes them vulnerable. • Many people may mistake them for alligators even though they are two completely different animals.

Habitat • • • Crocodiles live in a variety of different habitats such as rivers, swamps, lagoons, billabongs. (Saltwater crocodiles are able to swim in the ocean as well as the habitats listed above. ) When crocs get cold the come out to sunbathe to warm up their blood and get them going. They become lethargic when in cold water for an alotted amount of time. (Unlike alligators crocodiles are a tropical species and are highly sensitive to the cold. ) Most of the time they share their environment with several other animals including but not limited to: Fish, amphibians, turtles, insects, marine mammals, aquatic birds.

Diet • • • Crocodilians have somewhat similar diets although none eat the exact same prey. Their diet consist of small rodents, insects, fish, amphibians, small mammals, and birds. Larger species may consume larger terrestrial prey such as deer and similar prey depending on where they are located. Some have been known to consume humans who happen to be unlucky. Some crocodiles are cannibalistic occasionally preying on the younger, weaker crocs. They have very slow metabolisms and can survive long periods of time without food.

Appearance • • • Overall there are 23 species of crocodilians: 14 crocodiles, 2 alligators, 6 caimans, and 1 species of gharial. All varying in size and appearance. The dwarf crocodile (Osteolaemus tetraspis) is the smallest of all living crocodiles measuring at about 1. 5 m. (4. 9 ft. ) and weighing around 18 -32 kg (40 -71 lb. ). The saltwater crocodile (Crocodylus porosus) is the largest of all crocodiles and also the largest of all living reptiles reaching sizes of up to 4. 3 -5. 2 m. (14 -17 ft. ) and weighing in at 400 -1000 kg. (880 -2, 200 lb. ) and some have been recorded being even larger than this.

Gators v. Crocs • • • Alligators and crocodiles are often mistaken to be the same species although they are far from it. Alligators have a shorter and more rounded snout that shows no teeth while crocodiles have longer and more pointed ones which show their teeth while closed. Gators coloration tend to be darker than the coloration of crocodiles which happen to be a bit lighter. Gators aren’t adapted to life in saltwater while crocodiles are able to live in both fresh water and saltwater without any problems. Crocodiles have the strongest bite force in the animal kingdom, 3, 700 psi or 16, 460 N of bite force that was measured from a 17 ft. saltwater crocodile which beat the previous record of 2, 200 psi or 9, 800 N from a 13 ft. American alligator measured in 2005. Crocodiles are often larger than alligators and tend to be more aggressive as well.

Biology • • • Crocodiles have highly acute senses, an evolutionary advantage that makes them successful predators built for killing. Crocs are mostly nocturnal predators they hunt using their night vision to prey on those animals foolish enough to get close. They have light receptors in their eyes which include cones and numerous rods. A crocs sense of smell is very well developed which help them to detect prey and carcasses that are near or around the water. Crocodiles have great sense of hearing. They have tympanic membranes that are concealed by flat flaps that can be raised or lowered by muscles around them. They have the most acidic stomach of any vertebrate and they need to so they could digest bones, hooves, and horns from their prey.

Social Behavior • • Crocodiles are among the most social of reptiles even though they do not form social groups. They congregate in rivers tolerating each others company during feeding and basking in the sun. Most species are very territorial and highly aggressive. There is a form of hierarchy amongst crocodiles with the largest and heaviest males at the top having access to the best sunbathing spots, females, and even prey/carcasses. They are also very vocal animals producing a wide variety of sounds during different situations.

Reproduction • • • Crocodiles reproduce by laying eggs which are often laid in a hole or mound nest depending on the species. Nesting period ranges from a few weeks to around 6 months. The sex of crocodiles is determined by temperature and not genetically like humans are. At 30 degrees Celsius (86 deg. F) or less they will be female and at 31 degrees C (88 deg. F) the babies will be either sex while at 32 -33+ degrees C (91 deg. F) the offspring will be male. Temperature also affects growth and survival rate of crocodile young, which explains the sexual dimorphism in crocs. Incubation period averages at around 80 days and is also depndent on temperature.

Interesting Facts • Crocodiles outlived the dinosaurs by 65 million years. • They can’t lift or stick out their tongue. • They have sensitive nerves on their tongues/mouth that once they feel something touch or interact with it they just snap down in the blink of an eye. • They have no strength in their mouth when it comes to opening it back up. • The largest crocodile ever recorded in captivity was one named Lolong measuring at 6. 17 m. (20 ft. 3 in. ) and weighing in at 1, 075 kg. (2, 370 lb. )

Current Event Monster 3. 75 m crocodile captured after it was terrorizing fishermen http: //www. dailymail. co. uk/news/article-3578345/Monster-375 m-crocodile-captured-terrorising-fishermen. html

References • • • "Crocodilian Biology Database - FAQ - What's the difference between a crocodile and an alligator". Flmnh. ufl. edu. Guggisberg, C. A. W. (1972). Crocodiles: Their Natural History, Folklore, and Conservation. Newton Abbot: David & Charles. p. 195. ISBN 0 -7153 -5272 -5. Buchanan, L. A. (2009). "Kambara taraina sp. nov (Crocodylia, Crocodyloidea), a new Eocene mekosuchine from Queensland, Australia, and a revision of the genus". Journal of Vertebrate Paleontology 29 (2): 473– 486. doi: 10. 1671/039. 0220. Schmitz, A. , Mausfeld, P. , Hekkala, E. , Shine, T. , Nickel, H. , Amato, G. , and Böhme, W. (2003). "Molecular evidence for species level divergence in African Nile crocodiles Crocodylus niloticus (Laurenti, 1786)". Comptes Rendus Palevol 2: 703– 12. doi: 10. 1016/j. crpv. 2003. 07. 002. Eaton, Mitchell J. ; Andrew Martin; John Thorbjarnarson; George Amato (March 2009). "Species-level diversification of African dwarf crocodiles (Genus Osteolaemus): A geographic and phylogenetic perspective". Molecular Phylogenetics and Evolution 50 (3): 496– 506. doi: 10. 1016/j. ympev. 2008. 11. 009.