The faeces of the wombat have caused a stir in scientific circles. They are cubic, enabling the wombat to stack the droppings to mark its territory. According to Professor Tom Gilbert, recipient of the Lundbeck Foundation Research Prize for Young Scientists, this cube-shaped poop is an example of the elegant and creative work of evolution.
How can an otherwise unremarkable anal orifice release faeces shaped like a cube?
The question has long haunted scientific circles, and on Sunday 18 November 2018 a group of scientists from Australia and the USA were finally able to give an answer.
The announcement was made at the 71st annual meeting of the American Physical Society’s Division of Fluid Dynamics, which was held in Atlanta, Georgia, USA. And the following topic was on the agenda: ‘How do wombats make cubed poop?’
Evolution at play
The wombat is a muscular marsupial which can grow to around one metre in length and up to 35 kg in weight. It lives in Australia and Tasmania, preferably in areas with heath, woodland or scrub where it can dig extensive burrow systems, several metres below ground.
The wombat lives here for most of the day, but in the late evening, and again before dawn, it emerges to seek food. It is a vegetarian and digests its food so slowly that it can take as much as 14 days to travel through the wombat’s system to emerge as cubed droppings. The wombat is the only animal in the world to be able to do this. Tom Gilbert, Professor of Evolutionary Biology at the Natural History Museum of Denmark and previous recipient of the Lundbeck Foundation Research Prize for Young Scientists, describes the cubed wombat droppings as a remarkable example of the elegance and creativity of evolution when untraditional solutions are required: ‘The wombat must have gained a distinct evolutionary benefit from adjusting to cube-shaped poop, otherwise it wouldn’t have happened. As far as I know, no other animals have done this – not even rabbits, which also live in warrens and burrows underground,’ says Tom Gilbert, and he adds that evolutionary adaptation of this kind ‘can take place over a very short period if the need is great enough.’
Stacks its droppings
It is said that an animal is leaving its business card when it relieves itself – and in the wombat’s case this is absolutely true! The wombat, which has poor eye sight, uses the 80-100 malodorous, cube-shaped droppings it produces each day to make a mark:
It stacks them in places such as the tops of cliffs and rocks – almost like small cairns – to mark its territory above ground. This warns other wombats to keep away.
The researchers from the USA and Australia have examined the digestive tracts of a number of wombats euthanised following motor vehicle collisions on roads in Tasmania. And, on Sunday evening, the team leader – postdoc Patricia Yang from the Georgia Institute of Technology – explained to the participants of the annual meeting of the American Physical Society’s Division of Fluid Dynamics that the wombat is able to keep its intestinal content in a liquid-like state through very long sections of its digestive tract. The change to a solid state does not take place until the end, where the intestinal wall shows pronounced elastic properties. The American-Australian research team concludes that the complex interaction of these properties explains the unique droppings of this marsupial, and they will now investigate whether the wombat study could provide inspiration for novel, industrial production methods.
Source: American Physical Society/EurekAlert
For further details please contact:
Henrik Larsen, science journalist at the Lundbeck Foundation, tel. +45 2118 6377 or firstname.lastname@example.org