Posts tagged ‘South Africa’

April 18, 2010

The Cobra’s Hood

The Ring-necked Cobra (Hemachatus haemachatus)

When I was a young lad in South Africa we lived in a country house about an hour’s drive south of Johannesburg. We were surrounded by bush and veldt, so snake encounters were not unusual. When walking through the bush it was normal to tread carefully,and we walked by the rule of stepping on obstacles first rather than stepping over them and risk landing on an adder or a cobra.

One day I was walking down the verandah of the house with our kitten at my heels. I can’t remember what my 11 year old mind was thinking at the time, but what ever my daydream was, it was instantly erased when I heard the cat hissing at my feet. Looking down to the bristly cat first, and then ahead to the object of its fear, I saw a  large ‘rinkhals‘. It was a ring-necked cobra, raised up, hood spread and by now hissing out its own warning. It was still out of striking range, but well withing spitting range, so I scooped up the cat and stepped back. With the threat gone, the cobra’s hood relaxed and the snake disappeared under the house. I too relaxed, and I quietly thanked our kitten for paying attention when I was not.

New research  recently published in the Journal of Experimental Biology has given us some insights in how exactly the cobra manages to spread its hood. By carefully placing electrodes on muscles in the neck region, the researchers were able to determine the mechanisms of the cobra’s hood.  From the BBC:

Once the electrodes were in place, the scientists waited for the snake to recover before filming and recording the muscle activity as the animal flared its neck.

They found that just eight muscles were involved in “hooding” and that they were muscles that were also present in non-hooding snakes.

“This is an example of evolution’s remodelling [as] derived species emerge,” said Dr Kardong. “There’s been a change in the nervous system’s control over these muscles.”

Read the complete article at the BBC.

The functional morphology of hooding in cobras by Bruce A. Young and Kenneth V. Kardong. First published online April 16, 2010 Journal of Experimental Biology 213, 1521-1528 (2010)

Image from Wikipedia.


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