Two types of Crocodiles are found in Australia,
The freshwater Croc and the Salt Water (Estuarine) Croc
The salt water Croc is the biggest reptile in the world
Salt vs Fresh
1) Fresh water crocodiles have a narrower snout
2) Fresh water crocodiles and are smaller than the "Saltys"
3) Fresh water crocodiles can only live in fresh or slight
salty water, whilst the saltwater crocodile can survive in
both types of water.
4) Saltys lay eggs in nests of vegetation whilst freshwater
crocs lay their eggs in sand.
5) Fresh water crocs teeth are shaped more like needles for
6) Saltwater Crocs reproduce in the WET season while
Freshwater Crocs reproduce in the DRY season
Found along Australia's northern coast and up to 200km inland,
from Rockhampton on Queenslands "Capricorn Coast" to Broome
in Western Australia. (see map)
As the name suggests these crocodiles are mainly found in Estuaries where tidal rivers meet the sea. This watery habitat is often mangrove lined
They can also be found sometimes in the open sea or inland in freshwater swamps and billabongs
The worlds largest reptile the "Salty" has a broad "stubby" snout with cone shaped teeth.
Its average length is 4 meters but males 6 to 7 meters have been reported.
Saltwater Crocs have rows of bony scales on their neck and back
There colouring is mainly greyish brown with brown and yellow sides.
Their rear feet are webbed to aid with swimming.
It is thought that they live up to 70 to 100 years
Their clear eyelids enable them to see underwater.
The feeding strategy of a salt water croc is to wait close to the water's edge and pounce upon its victim in the blink of an eye .
The usual prey of younger crocs is smaller animals such as fishes and crustaceans crabs insects etc
Adults can also attack and eat larger animals by overpowering and then drowning them, (the teeth are designed more for holding) eg fish, turtles, birds, reptiles and mammals (dingoes wallabies) even domestic cattle and people
After the prey is dead the croc will break the prey up into smaller pieces by violent flicking of the head to snap or break bones or twisting and rolling the body
Larger crocs will also take carrion (dead animals) if hungry.
As already mentioned nesting takes place in the wet season after males fight for the females.
The female croc builds a nesting mound of vegetation, mud and soil (about 2 meters long)and lays between 40 and 60 leathery eggs inside the mound.
This mound raises the eggs above the water level hopefully saving them from damage
She then guards the nest for 3 months until the young crocs using a special egg tooth on the top of their snout break free from their eggs.
Carefully carrying her young in her mouth she takes them to the water.
In the wild only about 1% survive to be adult crocodiles.
Boy or Girl at Birth?
This sounds amazing but it is true. The temperature at which the egg is kept determines the sex of the baby crocodile !
If the egg is kept at 31.6 degrees Celsius it will be male. Hotter or colder it will be a female !
Often you will see a saltwater crocodile gaping (its mouth open). This enables the Croc to cool down, as a lot of their time is spent thermoregulating (maintaining their body temperature between 30 and 32 degrees Celsius) as Crocs are cold blooded (ie their blood temperature is effected by the weather around them)
Status of Estuarine Crocs in Australia
In 1970 Estuarine Crocodile become a protected species because prior to
this intense hunting had drastically reduced numbers
Though croc numbers have increased since 1970 many crocs are still lost, drowned in fishing nets etc.
Dangerous large crocs are relocated away from human contact if necessary