This one's the big 'un, folks.
The Saltwater Crocodile (Crocodylus porosus) is the largest of all extant crocodilians, and therefore the largest extant reptile in the world. It is known by many names, including the estuary crocodile, Indo-Pacific crocodile, and the Saltie, and is also called pukpuk by some of the Aboriginal peoples of Australia. Its range is far greater than the waters in and around Australia, however, and they can be found in India, Bangladesh, Sri Lanka, New Guinea and small island nations in the Indo-Pacific ocean. Saltwater Crocodiles are rarely depicted in the wandjina Aboriginal rock paintings, because it was believed that they had been banished from the freshwaters for being filled with bad spirits and growing too large. However, the depictions that exist can date back to 3,000 years. Contemporary Aboriginal art contains many more depictions of the Saltie.
Average-sized adult male Saltwater Crocodiles can grow to be 17 feet (5.2 meters) in length and weigh over a ton (2,200 pounds/1,000 kg). Older, more mature males have been recorded at lengths of 20.7 feet (6.3 meters), and one of them weighed in at 3,000 pounds (1,360 kg). But as with other crocodilian species, those kinds of giants are very rare today. Sexual dimorphism is more apparent in Saltwater Crocodiles than in almost any other crocodilian species, as females are much smaller than males. Average-sized adult females will be about 11.5 feet (3.5 meters) in length, and weigh about 330 pounds (150 kg).
The Saltwater Crocodile spends the most time in marine saltwater environments than any other crocodilian. They will venture out to sea in order to easily bypass large areas of land (using ocean currents) and to travel between landmasses separated by the sea. The diet of Saltwater Crocodiles depends their size and on what's available, and they consider almost everything to potentially be on the menu. Juveniles feed on small prey like crustaceans, fish, small mammals, and amphibians. Adults eat basically whatever they please, like large ground-dwelling birds, large mammals, marsupials, other reptiles and even sharks. Saltwater Crocodiles have an extremely strong bite. For larger males, calculated by regression from bites measured by smaller ones, they can exert a force of 7,736 lbf/34,410 N. Using the data from these studies, scientists have estimated the bite forces of long-extinct animals like ancient crocodilians and dinosaurs.
The mating season of Saltwater Crocodiles occurs during the wet season, when water levels are high. Salties are usually extremely territorial, males especially, but they will tolerate the presence of females (especially during mating season). Females choose the nesting site, constructing a mound of vegetation and mud that both parents will defend. In it, the gravid female will lay a clutch of 40 to 60 eggs. The loss of eggs cannot always be prevented, though, as sometimes flooding will was them away. They're also the favorite food of some other animals, like goannas. After about 80 days, the female responds to the cries of her hatchlings and helps to dig them out of the nest. She carries them to the water in her mouth and looks after them for several months.
The relationship between Salties and humans is fraught at best, because they view humans as prey and/or intruders when encountered in their territories. Although the Nile Crocodile is credited with more attacks on humans, that is largely due to the fact that human/Nile Crocodile encounters happen more often out of necessity. Whereas the general policy in co-existing with Saltwater Crocodiles is to avoid any water they are known to inhabit, due to their extremely aggressive natures. Attacks on humans by Saltwater Crocodiles outside Australia are difficult to measure, but there are estimated to be 20 to 30 per year. Saltwater Crocodiles have made some recovery in population since the time when many crocodilians were commercially over-hunted, but continued survival of their species is probably going to involve continued protection and conservation efforts.
Source for all images used in this post.