GOANNA CASE STUDY
The goanna is a lizard that is only found in Australia. It comes from the family Varanide. The type of goanna found in Kangaroo Island and along the east coast of Australia is the Rosenberg’s goanna. It, like the echidna, has also been living on the planet for a very long time. The other interesting feature about the goanna is that it is a reptile living in a temperate area. Reptiles mostly live in hot, desert areas to warm up their blood. The amazing thing about the Rosenberg, is that it is a lizard that lives the furthest away from the equator. What this tells us is the same thing like the echidna – the Rosenberg has also had to adapt to environmental climate in order to survive. It is the largest terrestrial predator on Kangaroo Island and it is also a predator of the echidna on Kangaroo Island, however it is a native predator. The feral cat is a predator of the echidna as well but is obviously not native to the island.
One of the main indicators of the Rosenberg’s goanna is that it lays its eggs in a termite mound for incubation during the winter months. Since it is a reptile, it would normally be able to lay its eggs in its warm environment but on Kangaroo Island it is not a hot, desert area, therefore the Rosenberg’s goanna has had to use this feature in order to survive.
During April and May, the goannas dig for winter burrows. If the sun comes out then the goannas have been seen to come out for a sunbake! The other amazing feature of the goannas is that they have more than one home for winter. Several winter burrows have been located and this means that they traverse from one burrow to the other. Another curiosity for research scientists is the conditions of these burrows. How the temperature and humidity affect these burrow conditions is of interest because it allows scientists to understand how goannas – (reptiles are called cold blooded animals) – are able to live through cold weather!
Goannas have a territory defending their limits. There is only an overlap of these territorial limits during the breeding season. Males roam between females’ burrows and we also don’t know about the fertilisation of the eggs. The female goanna can carry up to 12 eggs and when she is ready to lay them (usually after 21 days) she will find a termite mound that is able to incubate her eggs. The eggs are normally incubated for a 7 month period. When the eggs hatch, the baby goannas survive on the termites surrounding them and keep nice and warm as the temperatures inside a termite mound are approximately 33 degrees Celsius. The baby goannas stay in the mound for around 7-8 months as they wait for the temperature of the outside world to reach the same temperature as the termite mound. Therefore they would be seen to poke their heads out of the mound and check the temperature! They would normally venture out of their mound around the summer time. Baby goannas (the Rosenberg kind) have colourful spots on their body. As they grow older, these colours fade.
HANDY WEBSITES:
http://www.sthcoastherpsociety.bizland.com/goannas.chtml
http://www.abc.net.au/nature/island/ep6/
http://www.livingharbour.net/reptiles/lizards_goannas.htm
http://www.viridans.com/reppics/2287apr1.jpg
QUESTIONS:
- What does a goanna look like? How is it different to a lizard? Describe using words and diagrams.
- What does a goanna eat?
- Describe how a goanna burrow is made.
- What kind of environment would you normally find goannas and lizards?. Where are lizards and goannas most commonly found?
- What is most unusual about the Rosenberg’s goanna and why are scientists researching their habits and lifestyles?
These questions need to be answered by the end of the lesson! Remember to save your work from echidna case study and the goanna case study so you can use the information for the following TeachLive lessons!!
Good luck and don’t forget to follow my photo gallery stories and daily journal!
