gh WHAT DO PHALANGERS AND CATS HAVE IN COMMON?

The overwhelming majority of mammals produce sounds at the exhalation. Human beings also speak and sing at the exhalation, but during the inhalation they can only give a inarticulate squeak. The only exception are the feline representatives, including cats, pumas and cheetahs, which can produce sounds both when exhaling and inhaling. This is how the famous feline purr - a peculiar continuous pulsatory sound - is produced. Ilya Volodin and Elena Volodina, researchers of the Moscow Zoo, have discovered that the marsupials representative - the striped phalanger - is also able to produce continuous successions of pulsatory sounds during both phases of breathing - inhalation and exhalation. However, these sounds do not resemble the purr at all.

The phalanger male and female live in the Moscow Zoo in the "Night World" exposition. The animals slightly resemble big blunt-nosed rats, they are striped and have very long tails. Each of the phalangers occupies a wooden shelter fixed on the rear wall of the open-air cage. After feeding, when the light in the pavilion is switched from the "day" to the "night" mode, the animals get out of the shelters and start quarrelling. Having noticed the partner, the phalangers scream at each other until one of them cedes the disputable part of the open-air cage to the other and pulls out to its shelter. The researchers did not happen to hear any sounds produced on other occasions. Video-recording allowed to track the phalangers' breathing phase by phase. When exhaling, they compress the thorax and then abruptly draw in the abdomen. The inhalation starts from the abdomen and then they inflate the thorax screaming. The yells last from 3 through 15 seconds with the interruptions for about a second. The inhalation/exhalation phases are well distinguishable in each yell. It makes no difference for the phalangers at what phase to start screaming, but they finish the yell more often at the exhalation than at the inhalation.

Pulsatory sounds produced by the striped phalanger resemble the cat's purr by some characteristics, but differ significantly by other features. Thus, with both species, the sound pulsation period is shorter during the exhalation, than during the inhalation and the animals of both species make a short pause when switching from one phase of breathing to the other. However, the cat's purr is quieter and more monotonous that the phalangers' screams. The cats purr when they are pleased, but the phalangers scream when they are quarrelling. Besides, the felines purr without visible physical effort, the phalangers tense the body muscles noticeably while screaming. Therefore, the cats can purr as long as they like without getting tired, and the phalangers have to take a break for rest.

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