TAXONOMY, ANATOMY, SIZE & HABITAT

Taxonomy

Kingdom:      Animalia
Phylum:       Chordata (vertebrate)
Class:              Reptilia   
Subclass:      Anapsida
Order:            Testudines (protective covering)   
Suborder:      Pleurodira (sideneck)
Family:           Chelidae
Genus:             Chelodina
Species:          Oblonga

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Size

Adults – Growth is dictated by food supply so it is not possible to tell their age by size. Females are large and reach maturity when their  carapace length is 160 - 170mm so as to hold the clutch of eggs (16 –25). They can grow to a shell length of up to 40cm with the head & neck equally long. Females weigh from 1-2 Kg.  Males are smaller but have a longer tail and weigh up to 1 Kg. They are sexually mature when their carapace length is 140mm.

Hatchlings - Weigh about the same as a 10c coin. Their shells are initially soft but firm up over a few weeks once the turtle starts to eat.  Hatchlings have a high mortality rate due to predation by birds (ravens, kookaburras), dogs, cats and foxes. The danger is when they are still in the nest and when they emerge in August, high above the winter rains water-line, and have to run to the safety of the pond or lake. Each clutch of eggs may only have one or two survive out of a dozen or more eggs laid by the mother in the spring. Some nests are completely destroyed soon after laying.

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Habitat

Oblong turtles are common in rivers, lakes and swamps from Hutt River in the north right through to the Fitzgerald River in the south west of Western Australia. They prefer slow moving water but will enter rivers to migrate in summer if their habitat has dried out. Urban development around Perth has severely hampered overland migration and researchers have found the numbers have dropped by 10% in some suburban lakes over the last 10 years (2000 – 2011).
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Anatomy

The top shell or carapace is dark brown to black and the bottom shell, the plastron is pale. The skin of the rest of the body that protrudes from the shell is dark brown to black often with flecks. If the water is light and  silty then the turtles can be much lighter in colour. Older animals often have  tiny green plants or algae growing on top of their shell which is a great  camouflage in the billabongs and swamps.  Barbels, which  protrude from the chin,  are very sensitive to touch and have a role to play in courtship. The shell is  made up of bony plates that form over the ribs and fuse with them and the  shoulder and pelvic girdles. These plates are overlaid with skin/keratin  patches called scutes that are shed like our skin.  Thus the shell is a living, metabolising body part and is very sensitive to touch.

Cracked shells  are treated like we treat a cracked tooth. The wound is cleaned surgically while the turtle is under a general anaesthetic and given time to heal without infection by administering antibiotics and pain relief. Care of these injuries is specialised and is done by veterinary staff or highly trained wildlife rehabilitators under veterinary  supervision.
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