Question of the Week

How do giraffes vomit?

Sat, 16th Apr 2011

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Jesse Jones, via facebook asked:

How do giraffes vomit given that they have such long necks?


We put this question to Professor Alun Williams and Dr. Jonathan Holmes from the University of Cambridge...

Alun -   Well yes, that's a really interesting question and the answer is sort of yes and" alt="Giraffe" /> no. If you think about the giraffeís stomach, itís very similar to that of the cow and itís much more complicated than ours.  So, a giraffeís stomach has four chambers.  The first and second compartments are really big fermentation vats and the true stomach, their equivalent of our stomach, is the fourth chamber.  So when we vomit, the vomit comes out of our stomach and then up the oesophagus, and obviously out of our mouths.  In a giraffe, it would come out of the fourth stomach and it would sort of bypass the third stomach, and go into the first and second.  Itís extremely rare for the vomit then to go any further than that.  So, in a sense, yes, giraffes can vomit, but itís very, very rare that it actually comes out of the mouth.

Diana -   Giraffes may vomit, but generally, this would be from the fourth stomach into the second, but what could make it throw up in a way that was more visually similar to a human?

Jonathan -   I'm not an expert on giraffes as such, but of course, they are ruminants like cows and sheep, and other types of antelope.  That is to say, they chew the cud.  They have the capacity to regurgitate food from the main part of the stomach, the rumen, up to their mouths for further chewing to help the digestive process.  So, the oesophagus, the food pipe of giraffes, quite naturally and frequently works in reverse to bring food up to the mouth.  There is nothing physical that would stop it being sick.  There are some plants that can make cows sick to evacuate most of the contents of the rumen out of their mouths.  One is a small herb called cowbane, another is the rhododendron.  It is not common but cows that have been eating rhododendrons can be sick and we must bear in mind that the capacity of a big cowís rumen is anything up to 250 litres, 50 or 60 gallons.  So this can be a spectacular site, especially if a whole herd of cows have found a rhododendron clump.  I'm sure there are circumstances which could make a giraffe sick in the same way, and there would always be the danger of rumen contents getting into the lungs and causing a pneumonia.

Diana -   So, giraffes do regularly regurgitate food up their very long necks, though itís not quite the same as vomiting.  Jonathan also added that giraffe vomit from the rumen would be quite different from our own since the rumen contents arenít acidic.



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A message from CB Axel, listening to the show in Second Life:

"Horses don't vomit, so giraffes may not either." BRValsler, Sun, 10th Apr 2011

@NakedScientists surely if they really need to they just lower their heads to the ground like any first year uni student? was tweeted by @Doc_Turbo @Doc_Turbo, Sun, 10th Apr 2011

I wonder if giraffes also find it necesssary to shout for Hughie? Geezer, Sun, 10th Apr 2011

Actually, giraffes are more closely related to camels and cows than horses (which almost never vomit).  They have compartmented stomaches and regurgitate their food to chew the cud.  So they are capable of vomiting.  They just require more pressure to send the food up to the mouth.  The added pressure can cause health problems, though, especially during cases of sedation.

Source: RobMaule, Wed, 13th Apr 2011

Thanks, Rob - very interesting.

Meanwhile, anyone know how many bones a giraffe has in its neck?

Chris chris, Wed, 13th Apr 2011

Same number as a human RD, Wed, 13th Apr 2011

Well done! Many people fall for that one! chris, Thu, 14th Apr 2011

@NakedScientists This is actually a common cause of death for a giraffe. was tweeted by @justinimmel @justinimmel, Thu, 14th Apr 2011

@NakedScientists It seems they certainly can and one died in a zoo from excessive vomiting... Poor guy. was tweeted by @daiverd @daiverd, Thu, 14th Apr 2011

@NakedScientists I didn't know so many people were interested in this giraffe question. Google gave me so many results! was tweeted by @daiverd @daiverd, Thu, 14th Apr 2011

@NakedScientists Guess not. See horses. They are just big horses, no? distract listeners with this tangent instead was tweeted by @JamieBGall @JamieBGall, Thu, 14th Apr 2011

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