Who doesn’t remember the famous Crocodile Dundee? Worldwide movie success!
Australia is known for its dangerous wildlife too and crocodile are in the top 10 of dangerous Australian animals.
Let’s learn more about these beautiful and powerful creatures.
Saltwater Croc / Daintree River ©maximecoquard
Australia is fortunate to be home to two species of crocodile, the Freshwater Crocodile (Crocodylus johnstoni), which is found nowhere else in the world, and the vulnerable Estuarine Crocodile (Crocodylus porosus). In spite of their common names, both species can live in fresh or salt water.
1. Estuarine Croc or often called Saltwater Croc (“salties” nicknamed by Aussies)
Earth’s largest living crocodilian
Diet: Carnivore: opportunistic predators
> Able to feed on whatever they can overpower - sea turtles, goannas, wallabies, feral cats and pigs, dogs, kangaroos, cattle, horses, buffalo and even other crocodiles.
> to capture prey, they lurk patiently beneath the surface near the water's edge, waiting for potential prey to stop for a sip of water. Without warning, they explode from the water with a thrash of their powerful tails, grasp their victim, and drag it back in, holding it under until the animal drowns.
Size: Average-size males reach 17 feet (5 meters) but some specimens can reach 23 feet (7 meters) !!
Weight: Average 1,000 pounds (450 kg) but some of them can weighing 2,200 pounds (1,000 kilograms)!!
Average life span in the wild: 70 years
Where do they live?
An enormous range, populating the brackish and freshwater regions of eastern India, Southeast Asia, and northern Australia. They are excellent swimmers and have often been spotted far out at sea.
And in Queensland?
They are known to occur between Gladstone and Cape York Peninsula, and throughout the Gulf of Carpentaria. Although most commonly seen in tidal reaches of rivers, they also occur along beaches and offshore islands in the Great Barrier Reef and Torres Strait, and in freshwater lagoons, rivers, and swamps up to hundreds of kilometres inland from the coast.
2. Freshwater Croc OR “Freshies"
Endemic to Australia and occur in inland waters of northern Australia.
In Queensland, they are found mainly in the rivers and swamps of Cape York Peninsula, areas bordering the Gulf of Carpentaria and the north-west. There are also east coast populations found in the upper Herbert River, the Burdekin River catchment and the Ross River. Freshwater crocodiles also live in tidal reaches of some rivers.
Freshwater Croc ©christinewalsh
How to distinguish a freshwater from a saltwater croc ?
I don’t know if this matters because if you spot one, you’d better leave him alone and go… but :
First: it’s smaller (Males reach up to 200kg only for 2.5m long / Female grow to 1.8m long and weigh up to 150kg).
Second: it has a narrow snout and evenly shaped and sized needle-like teeth. There is also a distinguishing row of four large scales on the neck immediately behind the head.
INSTERESTING SPECIAL FACTS about CROCODILES
A prehistoric predator:
Crocodiles have reigned as key predators for millions of years. Differing little from their prehistoric ancestors that stalked the earth before the dinosaurs.
They have survived major upheavals, such as the break-up of the world's continents and the ice ages.
Today, crocodiles are one of the few remaining links to the prehistoric past.
A cold blooded animal:
Crocodiles use the water, sun and shade to maintain their preferred body temperature of 30–33 °C.
Crocodiles are unable to sweat. To avoid over-heating they may return to the water or lie with their jaws agape, allowing cool air to circulate over the skin in their mouths, it’s called ” thermoregulation”
A great survivor:
Crocodiles can convert as much as 50–70 percent of their food into growth and energy. (By contrast, humans use only 3–4 percent and up to 80 percent of our food is used to produce heat and maintain a constant body temperature). This efficiency means that they can go for months without eating!
A special Heart:
Crocodiles are one of the few reptiles to have a four-chambered heart (like mammals).
They can also stay underwater for extended periods of time because they have the ability to slow their heart rate, allowing them to hold their breath.
A crocodile has a constant supply of new teeth. Each time an old tooth falls out a new one will replace it.
Like a desalinization factory
They use their blood system to remove salt from their body. Salt glands embedded in their tongue tissue excrete excess salt when the animal is living in a highly saline environment.
Good sight and smell
Crocodiles are able to see underwater due to a transparent lid that closes over their eye for protection. They also have excellent night vision, thanks to a specialised retina, as well as a keen sense of smell. Small sensory buds around the top and bottom jaws allow crocodiles to detect vibrations - crucial when hunting in murky water.
All is about temperature!!!
The temperature of incubation determines the sex of the young
32°C = produces mostly males.
> or < 32°C = increases numbers of females.
EX GUMMY !!! Born in a farm, his egg was incubated at too
high temperature, which resulted in a malformation of his jaws…
In the wild, he would never have got the chance to survive…
While the saltwaters croc mums are really protective, freshwater croc mums rarely guard their nests. As a consequence over 70 percent of eggs laid are destroyed by flooding and/or eaten by feral pigs, goannas and snakes.
The future for crocodiles
Even if they are considered at low risk for extinction, crocodile are struggling.
Indeed, because saltwater croc leather skin is highly valued, they are suffering from illegal hunting in the world.
Habitat loss because of human development and antipathy toward the species because of its reputation as a man-eater continue to put pressure on the population.
Australia is one of the very few places in the world where estuarine crocodiles have a good chance of survival in the wild, and the only country where the freshwater crocodile is found. Because crocodiles are an important part of the food chain and help keep our wetland environments healthy and stable, protecting them is vitally important.
This is the responsibility of the Australians but also of all the visitors coming to the country. When visiting crocodile habitats, take care. Respect these animals and appreciate that, like other native animals, crocodiles are part of the natural and cultural heritage of northern Australia.
FOR YOUR SAFETY WHILE VISITING AUSTRALIA
"BE CROC WISE IN CROC COUTRY"
Never take unnecessary risks in crocodile habitat. I f there is a warning sign of NO SWIMMING, don’t go swimming!! It’s as easy as that… croc attacks happen when people take risks and don’t respect the rules…
A few examples of rules
Be more aware of crocodiles at night and during the breeding season, September to April.
Don’t approach water ’s edge (never prepare food or wash dishes for ex)
Never provoke, harass or interfere with crocodiles, even small ones.
Never feed crocodiles - it is illegal and dangerous.
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