The Saltwater Crocodile (Crocodylus porosus), also known as saltie, estuarine or Indo-Pacific crocodile, is the largest of all living reptiles, as well as the largest terrestrial and riparian predator in the world. The males of this species can reach sizes of up to 6.7 m (22 ft) and weigh as much as 2,000 kg (4,400 lb). However, an adult male saltwater crocodile is generally between 4.3 and 5.2 m (14 and 17 ft) in length and weighs 400–1,000 kg (880–2,200 lb), rarely growing larger. Females are much smaller and often do not surpass 3 m (9.8 ft). As its name implies, this crocodile can live in salt water, but usually resides in mangrove swamps, estuaries, deltas, lagoons, and lower stretches of rivers. They have the broadest distribution of any modern crocodile, ranging from the eastern coast of India, throughout most of Southeast Asia, stretching south to northern Australia, and historically ranging as far west as just beyond the eastern coast of Africa and as far east as waters off the coast of Japan.
The saltwater crocodile has a wide snout compared to most crocodiles. However it has a longer muzzle than the mugger crocodile; its length is twice its width at the base. The saltwater crocodile has fewer armour plates on its neck than other crocodilians. On this species, a pair of ridges runs from the eyes along the centre of the snout. The scales are oval in shape and the scutes are small compared to other species. The adult saltwater crocodile's broad body contrasts with that of most other lean crocodiles, leading to early unverified assumptions the reptile was an alligator. The head is very large. Skull lengths of more than 75 cm (30 in) have been confirmed for the species and mandibular lengths have been reported of up to 98.3 cm (38.7 in) (female skull lengths of over 50 cm (20 in) are exceptional). The teeth are also long, with the largest teeth (the fourth tooth from the front on the lower jaw) having been measured to 9 cm (3.5 in) in length. If detached from the body, the head of a very large male crocodile can reportedly scale over 200 kg (440 lb) alone.
The saltwater crocodile is one of the three crocodilians found in India, the other two being the more widespread, smaller mugger crocodile and the narrow-snouted, fish-eating gharial. Apart from the eastern coast of India, the saltwater crocodile is extremely rare on the Indian subcontinent. A huge population, consisting of many large adults, several over 6 m (20 ft), including a 7 m (23 ft) male, is present within the Bhitarkanika Wildlife Sanctuary of Odisha and they are known to be present in smaller numbers throughout the Indian and Bangladeshi portions of the Sundarbans. Populations are also present within the mangrove forests and other coastal areas of the Andaman and Nicobar Islands in India. Saltwater crocodiles were once present throughout most of the island of Sri Lanka but remain mostly within protected areas such as Yala National Park, which also has a large population of mugger crocodiles.
The primary behaviour to distinguish the saltwater crocodile from other crocodiles is its tendency to occupy salt water. Though other crocodiles also have salt glands that enable them to survive in saltwater, a trait which alligators do not possess, most other species do not venture out to sea except during extreme conditions. The only other species that exhibits regular seagoing behaviour is the American crocodile, but the American variety is still not considered to be as marine-prone as the saltwater crocodile. As its alternate name "sea-going crocodile" implies, this species travels between areas separated by sea, or simply uses the relative ease of travelling through water in order to circumvent long distances on the same land mass, such as Australia. In a similar fashion to migratory birds using thermal columns, saltwater crocodiles use ocean currents to travel long distances. In a study, 20 crocodiles were tagged with satellite transmitters; 8 of these crocodiles ventured out into open ocean, in which one of them travelled 590 km (370 mi) in 25 days. Another specimen, a 4.84-m-long male, travelled 411 km (255 mi) in 20 days. Without having to move around much, sometimes simply by floating, the current-riding behaviour allows for the conservation of energy. They will even interrupt their travels, residing in sheltered bays for a few days, when the current is against the desired direction of travel, until the current changes direction. Crocodiles also travel up and down in river systems, periodically.
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