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Friday, December 11, 2009

Minuscule early primate caught on film

By Matt Walker
Editor, Earth News


The tiny spectral tarsier, one of the shortest primates in the world, has been filmed hunting at night in the jungle of Sulawesi, Indonesia.

The tarsier stands 13cm (five inches) tall and has massive eyes that enable it to see in the dark. It belongs to the only group of carnivorous primates.

Tarsiers have evolved little in the past 45 million years and may have separated early from other primates.

A BBC team filmed the tiny tarsier for the natural history series Life.

Tarsiers are completely carnivorous, eating insects and occasionally small bats and birds.

Spectral tarsier (Tarsius tarsier)
Primitive but social

They have eyeballs that are bigger than their brains, and are believed to have the largest eye to body-size ratio of all mammals.

Their eyes are so big that they cannot move in their sockets, so the tarsier has to move its head to look around.

Unlike many nocturnal animals, a tarsier's eyes lack a structure called the tapetum lucidum which reflects light shining on it.

Because of that, the animals' eyes do not light up when a torch is shone upon them, which makes it difficult for researchers to spot tarsiers in the trees.

However, cameraman Justin Maguire managed to film a group of spectral tarsiers foraging around the tree they sleep in.

This tree was actually the aerial roots of a strangler fig.

Tiniest primate

Researchers have discovered that spectral tarsiers (Tarsius tarsier or T. spectrum) are quite social.

Not only do groups of tarsiers reside in the same "sleeping tree" each night, they also prefer to forage near to one another.

It is not clear why, because their foraging is less successful when other tarsiers are present.

But each tarsier may be able to put its huge eyes and sensitive ears to a use other than hunting: keeping a look-out for predators such as snakes.

At just 13cm tall, the spectral tarsier is one of the shortest primates in the world.

Tarsier (Tarsius tarsier)
Hunter on the prowl

An even shorter primate, the pygmy or lesser spectral tarsier (T. pumilus), was thought to be extinct until it was accidently rediscovered by Indonesian scientists in 2000, who trapped and killed one while catching rats.

In 2008, scientists from Texas A&M University, US, studied live pygmy tarsiers, which stand just 10cm (4 inches) tall, for the first time in over 80 years.

The smallest primate of all is thought to be Berthe's mouse lemur (Microcebus berthae) of Madagascar, which averages 9cm (3.6 inches) long and weighs just over 30g (1oz).

Lemurs are a separate group of primates from tarsiers, and are also considered to be relatively primitive.

"Tiny tarsiers" is broadcast within the Primates episode of the BBC series Life at 2100GMT on BBC One on Monday 14 December.