When Gerard Krefft named the species in 1873,[7] he intended to commemorate the man who first sent him preserved specimens, Australian native police officer and amateur naturalist Robert Arthur Johnstone (1843–1905).

[13] 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.

[citation needed] This species is shy and has a slenderer snout and slightly smaller teeth than the dangerous saltwater crocodile.

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.

[16] A population of freshwater crocodiles has been repeatedly sighted for a number of decades in the Ross River that runs through Townsville.

These prey may include crustaceans, insects, spiders, fish, frogs, turtles, snakes, birds, and various mammals.

Small prey is usually obtained by a 'sit-and-wait' method, whereby the crocodile lies motionless in shallow water and waits for fish and insects to come within close range, before they are snapped up in a sideways action.

However, larger prey such as wallabies and water birds may be stalked and ambushed in a manner similar to that of the saltwater crocodile.

When under water, the crocodile's heart rate slows down to one to two beats a minute, and muscles receive less blood flow.

When it comes out of the water and takes a breath, its heart rate speeds up in seconds, and the muscles receive oxygen-rich blood.

Brief and rapidly abandoned attacks have occurred, and were likely the result of mistaken identity (mistaking a part of the human as a typical prey item).

[25] A few incidents have been reported where people have been bitten whilst swimming with freshwater crocodiles, and others incurred during scientific study.