Mammal on Monday 7 - The Tasmanian Devil

The Tasmanian Devil (Sarcophilus harrisii) is a carnivorous marsupial only found today in Tasmania. It was once present over much of Australia, but by colonisation it was restricted to Tasmanian. 

I suspect that the fictional cartoon character, Taz is better known that the actual animal, but biologically the depiction of the Devil in the Looney Tunes cartoon series is rather way off the mark!

The TasmanianDevil is under threat of extinction because of a facial cancer that is spread between individual animals when they fight over food.  Populations of the Devil have fallen by 80% in many areas - and although this rapid decline is not continuing, a slow continued fall in population is now being seen.  Considerable efforts are being made to find a cure for the cancer and to establish disease free 'refuge' colonies.  This may even involve (eventually) the establishment of semi-wild populations on the main land. 

Although very bad for the animals, the cancer has a fascinating story.  Tasmanian Devils are very, very genetically similar to each other. When any fragment of a facial tumour is transferred between individual Devils it is not recognised as 'foreign' by the immune system of the second Devil.  This means that no 'defence' is mounted by the immune system and the tumour fragment can graft into the tissue of the second  Devil.  In many ways this is the same process as occurs when a person has a skin graft to repair damaged tissue.

All of the animals shown here are captive, from a sanctuary near Cradle Mountain.  I have seen Devils in the wild, but that was in the dim and distant past - ie when we still used film! And more recently I heard them calling and squabbling while on a multi day walk in The Walls of Jerusalem National Park in Tasmania.

One of the interesting things you can see here are the Devils red ears - they are supposed to get redder when the animal is agitated.  

The animal reclining on its back is not dead - it's resting. But you can see the entrance to the pouch and two of the four nipples that the young Devils use to feed.  Adult Devils are about the size of a small dog - but that still makes them the world's largest living marsupial predator.  The best way to describe them is stocky!  When they are born the young Devils weigh in at about 20 grams - and they have upwards of 20 siblings.  Only four of these manage to attach to a nipple in the pouch - and they stay that way for about 100 days.  The young leave the pouch at about 105 days, and then stay in the den rather than the pouch for another three months.

There is much research underway to find a cure for the cancer - but at present the most successful approach has been to form disease free population in places that remain isolated from other populations.  Research is also underway on a vaccine. 

It would be good if these approaches were successful.   SM