Freshwater crocodile

The freshwater crocodile (Crocodylus johnstoni), also known commonly as the Australian freshwater crocodile, Johnstone's crocodile, and the freshie, is a species of crocodile native to the northern regions of Australia. Unlike its much larger Australian relative, the saltwater crocodile, the freshwater crocodile is not known as a man-eater, although it bites in self-defence, and brief, nonfatal attacks have occurred, apparently the result of mistaken identity.

When Gerard Krefft named the species in 1873, he intended to commemorate the man who first sent him preserved specimens, Australian native police officer and amateur naturalist Robert Arthur Johnstone (1843–1905). However, Krefft made an error in writing the name, and for many years, the species has been known as C. johnsoni. Recent studies of Krefft's papers have determined the correct spelling of the name, and much of the literature has been updated to the correct usage, but both versions still exist. According to the rules of the International Code of Zoological Nomenclature, the epithet johnstoni (rather than the original johnsoni) is correct.

The genus Crocodylus likely originated in Africa and radiated outwards towards Southeast Asia and the Americas, although an Australia/Asia origin has also been considered. Phylogenetic evidence supports Crocodylus diverging from its closest recent relative, the extinct Voay of Madagascar, around 25 million years ago, near the Oligocene/Miocene boundary.

Below is a cladogram based on a 2018 tip dating study by Lee & Yates simultaneously using morphological, molecular (DNA sequencing), and stratigraphic (fossil age) data, as revised by the 2021 Hekkala et al. paleogenomics study using DNA extracted from the extinct Voay. Hall's New Guinea crocodile placement suggested in 2023 study by Sales-Oliveira et al.

The freshwater crocodile is a relatively small crocodilian. Typically, males can grow to a total length (including tail) of 2.3–3.0 m (7.5–9.8 ft) if a dominant male (although there are reported specimens of 4 metres in length (see below)), while females reach a maximum size of 2.1 m (6.9 ft). Males commonly weigh around 70 kg (150 lb), with large specimens up to 100 kg (220 lb) or more, against the female weight of 40 kg (88 lb). In areas such as Lake Argyle and Katherine Gorge, a handful of confirmed 4-metre (13-foot) individuals exist.^{[citation needed]} This species is shy and has a slenderer snout and slightly smaller teeth than the dangerous saltwater crocodile. The body colour is light brown with darker bands on the body and tail. These bands tend to be broken up near the neck. Some individuals possess distinct bands or speckling on the snout. Body scales are relatively large, with wide, close-knit, armoured plates on the back. Rounded, pebbly scales cover the flanks and outsides of the legs.

Freshwater crocodiles are found in Western Australia, Queensland, and the Northern Territory. Main habitats include freshwater wetlands, billabongs, rivers, and creeks. This species can live in areas where saltwater crocodiles cannot, and are known to inhabit areas above the escarpment in Kakadu National Park and in very arid and rocky conditions (such as Katherine Gorge, where they are common and are relatively safe from saltwater crocodiles during the dry season). However, they are still consistently found in low-level billabongs, living alongside the saltwater crocodiles near the tidal reaches of rivers.

In May 2013, a freshwater crocodile was seen in a river near the desert town of Birdsville, hundreds of kilometres south of their normal range. A local ranger suggested that years of flooding may have washed the animal south, or it may have been dumped as a juvenile.

A population of freshwater crocodiles has been repeatedly sighted for a number of decades in the Ross River that runs through Townsville. The predominant theory is that the heavy flooding common to the area may have washed a number of the animals in to the Ross River Catchment area.