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Freshwater Crocodile Fact File

Crocodylus johnstoni

Credit: JoachimKohler-HB, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons

Weight

30-60kg

(66.1-132.3lbs)

Length

2.1-3m

(6.9-9.8ft)

Lifespan

Wild 50 years

Captive 50 years

Diet

Carnivore

Fish, Crustaceans

Conservation Status

IUCN

Least Concern

Australia's Slender Snouted Crocodile!

The freshwater crocodile is the smaller of the two crocodile species which naturally occur in Australia with the other being the saltwater crocodile. They reach a length of up to 3m (9.8ft) long.

This species is a carnivore which will feed on fish, insects and crustaceans.

Females deposit an average clutch of 13 eggs which she will work to defend against predators. Despite this many are taken by predators.

They are threatened by habitat degradation and the invasion of cane toads which poison them when they try to consume them.

Read on to learn more about these remarkable reptiles.

Appearance

What does the Freshwater Crocodile look like?

The freshwater crocodile is a light brown color with darker bands on their bodies and tails. On the belly they are colored white.

The body scales are quite large and the back has wide, closely-knit armored plates.

They have a narrow snout with has 68-72 very sharp teeth.

On each leg is a webbed foot and the body ends with an incredibly powerful tail. Their eyes have a special clear eyelid which protects the eye while they are underwater.

The freshwater crocodile is one of the smaller crocodile species. These animals are considered sexually dimorphic meaning males and females differ in their appearance.

Males can grow up to 3m (9.8 ft) long and females up to 2.1m (6.9 ft), however the average size of these crocodiles is about 1.5m (5ft) long. They are slow growing animals and it usually takes a male about thirty years to reach 3m long. Males weigh 60kg (132.3lbs) while females weigh about half of that at 30kg (66.1lbs).

Adaptations

How does the Freshwater Crocodile survive in its habitat?


This species is well adapted for life in the water. Their eyes and nostrils sit high on the head allowing them to sit above the rest of the waterline while the remainder of the body is safe below the surface.

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Diet

What does the Freshwater Crocodile eat?

The diet of the freshwater crocodile consists mainly of fish, insects and crustaceans. The tapering snout of the freshwater crocodile is believed to be an adaptation to a diet of fish. As they are opportunistic feeders they will also prey on small animals, birds and reptiles when they are around.

Adults have been known to feed upon the juvenile crocodiles.

They will swallow stones to help with their digestion. They only drink freshwater.

Learn more about the Freshwater Crocodile in this video from YouTube

Range

Where do you find the Freshwater Crocodile?

Australia is the native home of the freshwater crocodile. Here they can be found in the states of Western Australia, the Northern Territory and Queensland.

Habitat

Where can the Freshwater Crocodile survive?

Freshwater crocodiles are generally found in freshwater billabongs, rivers, creeks and wetlands. They can live in saltwater but find it hard to compete with the bigger saltwater crocodiles.

Freshwater Crocodile (Crocodylus johnstoni)

Credit: Copyright. The Animal Facts.

Reproduction

How does the Freshwater Crocodile produce its young?

Freshwater crocodiles court each other during the early part of the dry season (around May).

The female will dig a hole in a part of a sand embankment to lay the eggs usually around August-September, mating occurs three to six weeks before the eggs are laid. The female will place the eggs about 12-20cm (5-8in) below the surface of the nest otherwise the eggs are at risk of being overheated by the sun. Laying typically takes place at night.

Usually all the females within a certain area will nest within a three week period in the season, and so there can be a lot of nests in the same area. If there are too many nests in a certain area, a female may dig up another females nest and destroy it.

The average clutch size is about 13 eggs however there can be as many as 20, and the incubation period for the eggs is 65-95 days.

The temperature of the nest is very important as eggs incubated at 32 degrees (89.6 f) or higher will produce male embryos, while temperatures of 20 degrees or lower will produce female embryos. A nest that fluctuates in temperature is best as it will produce embryos of both sexes.

The female will try and guard the nest but a lot of eggs are taken by predators.

Once the young hatch the mother will help them out of the nest and will carry them to the water in her mouth. She will guard over the young for a short period of time to guard them from predators, the exact time she does this for varies but she will leave them quite young.

Behavior

What does the Freshwater Crocodile do during its day?

They are not really a threat to humans unlike saltwater crocodiles, there is only one recorded attack on a human which on caused minor injuries.

They have sharper, less blunt teeth than the saltwater crocodile.

All the females in a certain area will usually nest within three weeks of each other in the breeding season.

Only 1% of the hatchlings live long enough to reach maturity, and some years so many eggs and hatchlings are killed that it is thought no new adults are added to the crocodile population.

In areas where there is not water year-round freshwater crocodiles will spend the time from late winter to late spring dormant in a shelter dug in to the creek bank.

Adults can produce a wide range of vocalizations including a roar, bellow or hiss.

Freshwater Crocodile (Crocodylus johnstoni)

Credit: NasserHalaweh, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons

Predators and Threats

What stops the Freshwater Crocodile from surviving and thriving?

Adults have very few predators. They are eaten by other crocodiles and hunted by humans. They also attempt to eat introduced cane toads which can lead to poisoning. Despite this they have persisted in areas with large cane toad populations for many years.

Eggs are taken by dingoes and introduced species such as wild pigs.

Cane toads may have assisted this species as they reduce varanid (monitor lizards) populations which are a main predator of this species.

Their population is considered stable across their range.

In some areas they may become entangled in a fishing gear causing them to drown. Degradation of water courses is also increasingly impacting this species.

Previously they were hunted in large numbers for the skin and the stuffed specimen trade. This continued until they were offered legal protection. Small numbers are farmed but the low quality of the skin has made this uncommon.

In some areas across Australia the species may be kept as a pet and small numbers are traded for this. Most of these individuals are taken from farms and other captive centers.

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Quick facts

Other names for the freshwater crocodile include freshie or Johnstone’s Crocodile.

Freshwater Crocodile (Crocodylus johnstoni)

Credit: CC BY-SA 1.0, https://commons.wikimedia.org/w/index.php?curid=94175

References

Swanson, S. and Parish, S., 2011. Field Guide To Australian Reptiles.

2nd ed. New South Wales: Pascal Press.Environment | Department of Environment and Science. 2011. Freshwater Crocodile. [online] Available at: <https://environment.des.qld.gov.au/wildlife/animals/living-with/crocodiles/about-crocodiles/freshwater> [Accessed 25 April 2020].

The Australian Museum. 2020. Freshwater Crocodile. [online] Available at: <https://australianmuseum.net.au/learn/animals/reptiles/freshwater-crocodile/> [Accessed 25 April 2020].

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