Monday, December 31, 2007

Animal of the Week -- December 31, 2007

Happy gnu deer!

It seems only right that I should ring in 2008 with at least a passing reference to the new species of giant rat and ungiant opossum discovered in the Foja mountains of Indonesia's Western Papua province a couple of weeks back. But there was a slew of marsupial AOTW in may, and you'll already know all about that giant rat, Mallomys -- unafraid of humans, five times the size of a city rat, closely related to several other species of giant rat found on the same island -- so why bother with Mallomys when there are other gianter rats, twice the size, that save human lives.

This week's animal is the 3 kg Cricetomys gambianus (Gambian pouch rat). Distributed across sub-Saharan Africa, from Nigeria to Zululand, these animals take their name from the Gambia where some of them live, the cheek pouches that allow them to transport fruit, seeds, and other foods, and from their rattiness. Although they are not actually that closely related to Norwegian or black rats with which you may be more familiar if you haven't spent substantial time in Africa.

You can distinguish Gambian pouch rats from their close relatives, Emin's pouch rats, not by their ability to make a bed or their sobriety on TV, but by their coarser brown fur and their single-note squeal which contrast with the latter's silky grey fur and multi-pitch squeaking (presumably the link to Emin).

Able to have nine litters a year, these animals occasionally reach pest proportions in some towns and agricultural land where they can destroy crops. The rats have no natural predators, because, while the occasional one might be eaten by opportunist snakes, cats, dogs, eagles, and mongooses, these giant rats, when threatened, band together and rear up on their hind legs to see off aggressors.

If you are feeling uneasy about the prospect of bands of bipedal squealing giant rats, don't worry. Humans have the upper hand, both species of pouched rat are highly regarded as food in much of their range. More pleasingly though, these animals are increasingly kept as pets. Humans have also begun to exploit the rats' excellent sense of smell, in Mozambique they have been trained to sniff out undetonated landmines, and even more implausibly they are now being trained to diagnose tuberculosis by smelling saliva samples. No, really, they can get through hundreds of samples in much less time than humans using conventional diagnostics and they are much cheaper, more portable, and less likely to go wrong in tropical Africa than other tests.

What wonderful rats!

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