Animal Diaries Archive

Size Matters!

8 August 2008

We are often asked how big certain snakes can grow, and this is a tricky question to answer. In some species of snakes, like the Mulga snake (pictured), males can grow up to three metres; much larger than the females who only grow to about 1.5 – 2 metres. It is the opposite in large python and boa species such as Reticulated Pythons and Anacondas, where the female reaches a larger size.   

Many factors play a part in determining how large a snake grows. Some of these include seasonal variation, availability of prey and geographical isolation. In species which have a large distribution such as Eastern Brown snakes, animals that occur in South Australia have a smaller adult body size than those that occur in Northern Australia. This could be because the warmer climate in the top half of Australia allows them to feed on prey for more months of the year rather than shutting down during the winter months.  

Tiger snakes also have a large distribution throughout southern Australia and occur on a handful of islands. One particular island is inhabited by Mutton Birds during their breeding season. Tiger snakes on Chapel Island feed solely on young Mutton Birds which are rich in Iodine, Phosphate, Zinc and Calcium. The Iodine stimulates growth causing these particular Tiger snakes to be much larger than their relatives on other islands and the mainland.   

Another point of interest is that extremely large snakes and extremely small snakes can live side by side in the same ecosystem in almost every environment on earth, contributing to making the serpent order the most successful predators on earth.