Saturday, May 17, 2008

The Platypus

The first platypus to make it to England from Australia in 1799 was received by naturalists as a hoax. The species has characteristics of birds, reptiles, and mammals. And did you know that males have poisonous spurs on their hind legs? A sting can kill a dog or cat. And then there's the radar-like bill that senses both pheromones and electrical fields.

Scientists have finally decoded the genome for the 150 million year-old platypus, revealing an even stranger beast. But first, a poem by Ogden Nash:
I like the duck-billed platypus
Because it is anomalous.
I like the way it raises its family
Partly birdly, partly mammaly.
I like its independent attitude.
Let no one call it a duck-billed platitude.
While the platypus has only two-thirds of the molecular letters of DNA that human beings have, we both have about the same number -- 18,500 -- of genes. The genome was like nothing scientists had seen before, according to a Washington Post article earlier this month.

With mammals, there are two chromosomes, X and Y, which are paired differently to make males and females. The platypus has 10 sex chromosomes. Platypus milk, which is secreted from abdominal patches instead of nipples, changes in nutritional complexity according to five or more genes that turn on in sequence (similar to kangaroos). This is of apparent interest to the dairy industry.

The genome tells us that the venom males use evolved differently than snake venom, but started from molecule and ended up very similar.

Scientists are still baffled by the platypus's ability to detect electrical fields -- they could not locate any genetic clues to this strange ability.

The short video below from National Geographic shows the odd beast in action, including some platypus battle scenes.



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