Thursday, September 24

Tiny primate ‘talks’ in ultrasound

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ULTRASOUND TALKS: In this photo taken on Jan 20, 2006, two Tarsier primates look around as they cling onto trees in a widlife sanctuary on the central Philippines island of Bohol. — AFP photo

PARIS: One of the world’s smallest primates, the Philippine tarsier, communicates in a range of ultrasound inaudible to predator and prey alike, according to a study published yesterday.

No bigger than a man’s hand, Tarsius syrichta can hear and emit sounds at a frequency
that effectively gives it a private channel for issuing warnings or ferreting out crickets for a nighttime snack, the study found.

Only a handful of mammals are known to be able to send and receive vocal signals in the ultrasound range, above 20 kilohertz (kHz), including some whales, domestic cats and a few of the many species of bats.

And few of these can squeal, screech or squawk at the same sonic altitudes as the saucer-eyed tarsier, which up to now had been mistakenly described as being “ordinarily silent,” researchers found.

Its finely-tuned ears are capable of picking up frequencies above 90 kHz, and it can vocalise in a range around 70 kHz. — AFP

By comparison, humans generally can’t hear anything above 20 kHz, and a dog whistle is pitched to between 22 and 23 kHz.

A team of scientists from the United States and the Philippines led by Marissa Ramsier of Humboldt State University in California gathered their inaudible results in two ways.

First they captured six of the docile nocturnal creatures and placed them inside custom-build sound chambers to test their sensitivity to high-pitched sounds.

After the experiments, the rare and endangered animals were returned unharmed to their natural habitat, on the Philippine island of Mindanao. — AFP