Crocodiles

Crocodiles (a group that includes crocodiles, alligators, caimans and gharials) have an evolutionary history that spans more than 200 million years.

Overview

There are 22 extant species but only two of these are found in Australia: the large Saltwater Crocodile (Crocodylus porosus) and the smaller Freshwater Crocodile (Crocodylus johnstoni).

Both species have long snouts, short legs with webbing between their toes and long, laterally-flattened tails. Their backs are protected by a dorsal armour of bony plates embedded in the skin.

Common questions

The Saltwater Crocodile, Crocodylus porosus, also known as the Estuarine or Indopacific Crocodile, is the largest living reptile. Large males can exceed six metres in length and weigh more than 1,000kg. The females are smaller, usually around three metres and weigh up to 150kg. The largest extinct crocodile, Deinosuchus (meaning terror crocodile) lived in North America during the Cretaceous; a reconstructed lower jaw measured 1.8 metres. Deinosuchus may have grown to 11 metres and weighed around 6,000kg.

This depends on the level of activity. A study on Freshwater Crocodiles (Crocodylus johnstoni) found that active dives were generally less than one minute and resting dives around 12 minutes. However, in situations where the crocodile was avoiding a threat, dive times were greatly extended. In this situation, one 5kg crocodile stayed submerged for 344 minutes and a 42kg crocodile only resurfaced after 402 minutes.

Fact sheets

https://collections.qm.qld.gov.au/topics/430/saltwater-crocodile

Saltwater crocodile

The Saltwater Crocodile is a broad-snouted species that grows to a large size (up to 7 metres but rarely more than 5 metres). This is the largest of all living crocodiles.

Learn more

https://collections.qm.qld.gov.au/topics/429/freshwater-crocodile

Freshwater Crocodile

The Freshwater Crocodile is a narrow-snouted species that grows to 3 metres.

Learn more

Images

Freshwater Crocodile, Crocodylus johnstoni. Image credit: Queensland Museum, Bruce Cowell
Saltwater Crocodile, Crocodylus porosus. Image credit: Queensland Museum
Saltwater Crocodile, Crocodylus porosus. Image credit: Queensland Museum, Gary Cranitch
Saltwater Crocodile, Crocodylus porosus. Image credit: Queensland Museum, Bruce Cowell
Freshwater Crocodile, Crocodylus johnstoni. Image credit: Queensland Museum, Bruce Cowell
Saltwater Crocodile, Crocodylus porosus. Image credit: Queensland Museum