Expansa

               Macrochelodina expansa (Grey, 1856)
                         Broad-Shelled Turtle

Macrochelodina expansa is the largest of all Australian snake-necked turtles. The carapace can reach almost 50cm and with the neck fully extended, the adult female can reach up to 85cm tail tip to snout!
Macrochelodina expansa is distributed in southeastern Australia west of the Great Dividing Range. It is found throughout the Murray-Darling drainage to the south of Murray River in Victoria. It extends well into the Goulburn River. The distribution overlaps that of C. longicollis in places. It inhabits lagoons, lakes, rivers and swamps and other permanent boddies of fresh water, such as water holes. The carapace is light olive-green to brown and the Plastron is bone-coloured

Expansa2




Female Macrochelodina expansa with appx. 3.5kg and 35cm carapace lenght

Plastron view of adult Male

Head of adult female.
Large animals can reach almost 50cm Carapace length !

Breeding
Macrochelodina expansa typically lays its eggs during the Australian autumn, between March and May.
This is the only Australian snake necked turtle that lays eggs as winter approaches, rather than in springtime. The eggs undergo a cooling period, before starting to develop in the following spring and summer. Together with the much deeper nesthole, compared to all other snake-necks (deeper also means cooler), the eggs take 6 month to hatch in nature. Macrochelodina expansa is an typical represantive of those turtles, in which the eggs undergo a diapause. The end of the diapause must be triggered by a change in temperature.
For successfull breeding in captivity, the eggs are kept at 18 degrees for 1-3 month before incubating them at 27 - 28 degrees for the remaining incubation period.
Sexual maturity is reached at about 30cm carapace lenght for females and about 20cm for males. This may be after 10 years in nature and approx. 5 years in captivity.

1 day old hatchling of Macrochelodina expansa.
Average weight is between 8 and 10g and they have
a carapace lenght of 35mm

Hatchlings are ready to leave the egg in captivity after
about 4 month, if incubated at 18 degrees for 1 month,
followed by 28 degrees for the remaining time.

Plastron view of hatchling

Macrochelodina expansa has typically 7-8
lamellae on the upper part of their front limbs.

9 month old juvenile