Highlights
- The saltwater crocodile, Crocodylus porosus, is recognized as the largest living crocodile species in the world, known for its impressive size, aggressiveness, and powerful bite, making it one of the planet’s top predators.
- Their habitat spans across Southeast Asia and northern Australia, thriving in both freshwater and saltwater environments, and demonstrating remarkable adaptability by also traveling over land with ease.
- Commonly referred to as the Indo-pacific crocodile, estuary crocodile, or marine crocodile, their presence is significant in Australia, with a notable decline in populations observed in Asian regions.
- Adapted for long-distance travel, these crocodiles exhibit the extraordinary ability to migrate by sea, covering distances of up to 1,000 km and reaching locations far from their typical habitats, supported by specialized glands that excrete excess salt.
- Dietary habits of the saltwater crocodile range widely, from insects and small fish in younger individuals to larger prey including mammals and occasionally humans in adult crocodiles, with the largest individuals known to attack sizable animals like buffaloes and sharks.
- Reproductive behavior sees these crocodiles laying up to 60 eggs, with the mother fiercely guarding the nest and young, though offspring mortality rates are high due to predation.
- Conservation threats include hunting for their valuable skin and loss of habitat, with historical overhunting drastically reducing their numbers. However, stricter regulations and conservation efforts have led to significant population recovery, especially in Australia.
- The largest crocodile in captivity is named Cassius, measuring 5.48 meters and residing in Australia, holding a record in the Guinness Book of Records since 2011 as the largest captive crocodile.
The saltwater crocodile, Crocodylus porosus, is the largest crocodile in the world, and due to its size, aggressiveness, and deadly bite, it is considered the largest predator on our planet. They live in Southeast Asia and northern Australia, well adapted to both freshwater and saltwater, and they often travel on land without problems.
It is also known as the Indo-pacific crocodile, estuary crocodile, or marine crocodile. In Australia, this species is very popular, especially in the northern regions, where an estimated 100-200 adult specimens have been found. In Asia, the number of specimens has declined greatly, with only a few groups remaining in the southeast.
Some groups have been observed in areas far beyond the usual ones, which is credible because it is known that these crocodiles travel great distances by sea, and live in both water and land, freshwater or saltwater. They resist saltwater because they have numerous glands in their mouth that remove excess salt. However, it has been found that in the rainy season, they prefer sweet waters, swamps, and rivers, and in the dry season they prefer estuaries and seawater.
An adult specimen is 5-7 m long and can weigh about 800-900 kg.
The male is larger than the female, but both have their bodies covered by thick, scaly skin, which makes their skin very valued in the leather industry. Especially on the back, the scales are large as plaques, and in the neck area, they are small and symmetrical. The color varies from dark gray to light gray, with a yellow or whitish ventral side. The muzzle is very wide, with deep pores, and the jaws contain about 64 sharp and strong teeth of different sizes, which if broken or when they fall down, grow back.
Distribution and habitat
The saltwater crocodile is the species of crocodile with the largest distribution. It is found in Sri Lanka, the east coast of India, Southeast Asia, and Australia to the Caroline Islands in the Western Pacific. The saltwater crocodile is considered extinct between Singapore and Seychelles and possibly even in Thailand. This species is capable of migrating through great distances of up to 1,000 km. It has been reported that some lost specimens have even reached Japan, Fiji Islands, and Cocos-Keeling Islands.
Just as the name suggests, the saltwater crocodile has a very good tolerance to saltwater, being helped by glands positioned on the tongue that excrete salt. The saltwater crocodile can be found in the willow waters near the coasts and in rivers, often in mangrove forests, but also on the high seas, freshwater rivers, lakes, and marshes, up to 200 km inland.
Individuals migrate between habitats depending on the season, rainy or dry, and dominant mating males usually force younger crocodiles out of freshwater habitats to peripheral habitats. The least dominant individuals may be forced to reach the high seas, moving along the coast in search of rivers.
Behavior
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The saltwater crocodile is a strong and opportunistic predator and feeds on a wide variety of animals. Young animals feed on smaller animals such as insects, amphibians, crustaceans, and fish, and adults also feed on reptiles, birds, and mammals. The largest specimens occasionally attack larger animals such as dingo dogs, wallabies, domestic animals, and even humans, and from time to time they will even eat corpses.
Saltwater crocodiles can swallow stones to help them grind food in the stomach. When the territory of the saltwater crocodile overlaps with that of the Australian freshwater crocodile, Crocodylus johnstoni, the saltwater one will win the food competition and sometimes even eat the latter.
The saltwater crocodile
It is a very dangerous prey animal, that in order to feed attacks everything in its path, including humans. Its favorite food consists of kangaroos, monkeys, buffaloes, tigers, wild boars, fish, and sharks. Offspring feed more on small fish and shellfish, reptiles, amphibians, and insects. These crocodiles do not move much during the day because they prefer to stay lethargic in the sun or in the water, but at night they become very active, hunting for food.
Male adults delimit and defend their territory by opting for the best regions, and when they are in mating, during November-March, they remove their rivals from the female side.
Mating is done in water, and reproduction is oviparous. Each female lays a number of 60 eggs in nests dug on the banks of rivers, well above the water level. The eggs are guarded by the female, and after hatching, the offspring are protected by the mother for a period of several weeks. The mortality of offspring is 99% due to the large number of predators, which besides newly hatched babies, also consume eggs. The offspring have yellow scaly skin with black spots and stripes, especially on the back of the body and tail.
Young saltwater crocodiles start to leave their mother at about eight months of age, and territorial behavior begins at two and a half years of age. Sexual maturity is reached at approximately 12 to 14 years of age in females, at a body length between 2.1 and 2.5 m, but at an age between approximately 16 and 17 years, and a length between 3.1 and 3.3 m, in males. Like other crocodiles, the saltwater crocodile has the potential to be long-lasting, surviving up to over 65 years or even more than 100 years.
Threats
In addition to the fact that the saltwater crocodile is hunted for meat and eggs, it has the most commercially valuable skin of all crocodile species. Unregulated hunting during the 20th century caused a dramatic decline in populations, with the population of saltwater crocodiles in Australia reduced by about 95% in 1971. Fortunately, since then the population has recovered significantly, and although hunting is now illegal, it still persists in some countries where legislation is ineffectively enforced and trade in saltwater crocodile products is difficult to control.
Another big problem for the saltwater crocodile is the loss of habitat. In northern Australia, most of the saltwater crocodile habitat has been literally trampled by wild water buffalo, while water buffalo eradication programs have significantly reduced this problem. Otherwise, even if there are large areas of habitat, subtle changes in it can cause problems.
The largest crocodile in captivity
The largest crocodile in the world that lives in captivity is called Cassius and is an Australian saltwater crocodile, Crocodylus porosus.
Cassius entered the Guinness Book of Records in 2011 when it became the largest crocodile in captivity. It measures 5.48 meters, weighs about a ton, and lives in the Australian Zoo Marineland Melanesia on Green Island, which currently has over 50 crocodiles, from young creatures to more mature specimens. Cassius is about 100 years old and is also the largest crocodile ever caught alive in Australia and is believed to be able to eat a man easily. It was brought by truck from about 3,200 kilometers from the Northern Territory of Australia to Green Island in 1987.
Lolong
The old record for the largest crocodile in captivity was held by a crocodile named Lolong, who died in 2013. At the time it was measured at the Eco-Park Research Center in Bunawan in 2011, it was 6.17 meters long. Lolong lived in captivity in the Philippines and weighed more than 1,000 pounds.
Final words!
It is possible that the biggest problem in preserving the saltwater crocodile is its reputation as a very dangerous animal. Although human mortality from a saltwater crocodile is not common, the negative attitude toward this species makes protective measures difficult to implement.
