Posts Tagged ‘Avian Relatives’


May 7, 2008

I have a young cousin — and I thank you, Andrew — who recently introduced me to the word “puggle” which I think is a fine word. It means baby platypus.

I see that dog breeders with too much time on their hands have also introduced a hybrid dog breed by the same name, but I will use the word as it should be used, to describe baby platypuses. If dog breeders want to cross pugs and beagles, let them find a new name for the result.

Having just learned the word, I was anxious for an opportunity to use it, but a blog about birds seemed an unlikely place. But today comes news from the science magazine Nature that scientists have successfully mapped the entire genome of the platypus. That is of interest to birders because some of the genes found in the platypus were, until now, known only in birds. Said differently, birds and platypuses are distant relatives, sort of like Andrew and I.

For instance, platypuses share with chickens a gene for a type of egg-yolk protein. Puggles are born from eggs; but treated to mothers’ milk, like mammals, as soon as they are born. They possess microRNAs which chickens have, plus different microRNAs which only mammals possess. And, unlike mammals, platypuses have two matches for what scientists call the ZPAX genes which, until now, had been found only in birds, fish and amphibians. These are the genes that determine the sex of puggles. Ten sets of chromosomes do that job instead of two which is enough for humans: An X and a Y result in a baby boy; two Xs result in baby girls.

Platypuses have X chromosomes, but they are much more like the Z chromosomes found in birds than the usual mammalian X. “The sex chromosomes are absolutely, completely different from all other mammals. We had not expected that,” said one of the scientists. And the Y chromosome, which platypuses possess, seems to have nothing to do with gender.

Platypuses are “monotremes.” (From the Greek monos ‘single’ + trema ‘hole’) Analogous to avian cloacas, they have but one opening for the intestinal, urinary, and genital tracts.

Platypuses are the oldest surviving branch of all mammals on the earth today. They got their start on the ancient continent of Gondwana which split into modern Australia and South America. Monotremes on South America died out but platypuses survive on the East coast of Australia and on Tasmania. They lay eggs, but make milk for their babies; they have fur coats and an aquatic life style; they forage for food underwater using an electro-sensory system in their duck-shaped bills. The males grow spurs on their rear legs which produce venom strong enough to kill dogs and incapacitate humans; a venom remarkably similar to that produced by venomous snakes.

To quote the scientists again, “There is nothing quite as enigmatic as a platypus.” But don’t take their word for it. Here is Odgen Nash on the subject:

The Platypus

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.


You can see video from Nature here and read newspaper articles here and here.


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