The saltwater crocodile, the living dinosaur

With over 6.5 meters long and weighing over 1,000 kg, the saltwater crocodile (Crocodylus porosus) is the largest living reptile on the planet as well as the largest terrestrial predator in the world. Also known as saltie, estuarine or Indo-Pacific crocodile, an adult male can reach 6-7 meters and weigh between 1,000-1,200 kg while a female saltie is much smaller and do not generally exceed 3 meters. The largest one in captivity ever officially measured was Lolong, measured at 6.17 meters and weighed 1,075 kg. Unfortunately, he died of congestive heart failure in February 2013.

Saltwater crocodiles have a wider snout than most crocodiles. Their skull may reach up to 75cm in length. A pair of ridges runs down the snout from the eyes. Their broad body led to early reports that they were a variety of alligator. They have oval shaped scales. Their limbs are short and strong. Juveniles are pale yellow in colour with black stripes along their body and tail. When they mature most become a dark greenish colour. Some may remain a pale yellow though or may be quite dark. They have light tan and grey areas on some parts of their body.  The underside on both juveniles and adults is white or tallow. They have a grey tail with dark bands. This giant creature has a heavy-set jaw with between 64-68 teeth.

The saltwater crocodile lives for about 70 years. However, some specimens have also been found to live for more than 100. They have a wide habitat range as they have a high tolerance of salinity. They can live well in fresh water. Biologists have found them living up to 235 kilometers away from the sea. As its name implies, this species can also live in salt water, but usually resides in mangrove swamps, estuaries, deltas, lagoons, and lower stretches of rivers. They are most commonly found on the coasts of northern Australia, and on the islands of New Guinea and Indonesia. It ranges as far west as Sri Lanka and eastern India, along the shorelines and river mouths of southeast Asia to central Vietnam, around Borneo and into the Philippines and in Palau, Vanuatu and the Solomon Islands. Because of their ability to live in the open ocean for long periods of time, they can cross vast expanses of ocean to reach new areas. Not surprisingly, their population is widespread in other areas such as the Pacific Islands, Fiji, and Papua New Guinea.

Due to their formidable size and wide geographical range, saltwater crocodiles are considered to be one of the most dangerous animals on earth. They can eat anything and are easily capable of devouring almost any living thing that would enter its territory, including birds, buffalo, wallabies, monkeys, cows, wild boars, crabs, fish, turtles, and sharks. They are hyper-carnivorous opportunistic predators, with the flexibility of adapting food depending on what’s available. This heavy-weight creature can also stay alive with very little food. With their ferocious and aggressive nature, and because of their mammoth size and territorial disposition, these carnivores are the largest of all crocodilians that are potentially dangerous to humans.

Saltwater crocodiles are able to leap as high as 2 meters. These crocs can easily stay underwater for at least an hour since they have the ability to reduce their heartbeat rate to 2-3 beats per minute. This implies that, they would wait patiently underwater until they see their prey approaching the water’s edge. They would suddenly explode out of the water with a thrash of their strong tails, hold the prey by their jaws and drown it under water. They can move very quickly on land and in the water, as also have an excellent sense of hearing, which they utilize while locating its prey. Saltwater crocodiles are considered very intelligent and sophisticated animals. They communicate with each other using sounds, as also chemical and visual signals. Body posture also plays an important role in signalling, e.g., raising of the snout would mean submission, while arching the tail would signal a display of threat. The glands present underneath their chins and the cloacae transude a ‘musk’, which is thought to be playing a role during courtship or marking their territories. They communicate by barks and are thought to display four different calls, including a high-pitched distress call performed by juveniles in a series of short barks. Threat calls consist of a hissing sound made at intruders. The hatching call is performed by new-borns as a high-pitched short bark, and finally, the courtship bellow is heard as a long, low growl.

Saltwater crocodiles shut off only half of their brains during sleep, keeping the other half alert to danger. The complex central nervous system keeps the right eye open when the left side of the brain is awake, and vice versa. They have a strong homing ability with which they would find their way back home, be it in the same river or a different another river system. Research suggested that a crocodile that has been captured from one place and released somewhere else would return back to its original residence anytime between 10 days and 3.7 years.

The act of mating of the salties occurs underwater, which can hardly be seen. Their complex mating ritual includes rubbing their heads together with their bodies. The crocodiles mate in the wet seasons, as the water rises to the highest levels. As the water warms with the incumbent wet season, these creatures start mating frequently. The males will mate with multiple female crocodiles during their breeding season, and generally play no role in parenting. As the females select a site for nesting, both the sexes engage in defending their nests along tidal rivers or freshwater areas. The nest, normally, is a mound made of mud and vegetation. The female lays 40-60 eggs. The female croc would guard the nest for 80 to 98 days. However, they often loss the eggs because of high flooding and occasionally to other predators. As the eggs develop, the female would help its babies out as it hears their screeching sounds. Baby crocodiles are often predated by larger crocodiles, predatory fish, monitor lizards, various aquatic and raptorial birds. In some ranges, they also fall prey to leopards and tigers. Only 1% of the juveniles reach their complete adulthood. It takes almost 7-10 years approximately for a baby saltwater crocodile to grow up.

This extremely territorial animals are at the apex of the food chain. With the big cats avoiding the territories of these dangerous creatures, it is needless to say that these crocs have no known predators. The present population estimate of the saltwater crocodile ranges from 200,000 to 300,000 worldwide and are considered to be at a low risk of extinction. The saltwater crocodile is not a threatened species. The IUCN 2.3 has categorized them under the ‘LC’ (Least Concern) species list.