Maths formula proves giraffes can swim

Mathematics has proven that giraffes can swim - even though they wouldn't be very good at it and nobody has ever seen them do it. Whereas most large animal are extremely good swimmers, it has often been said that giraffes are unable to swim or wade. The authors of the new study hoped to test this oft-quoted theory by using a digital giraffe rather than a real one. Dr Donald Henderson, of the Royal Tyrrell Museum of Palaeontology in Canada, and Dr Darren Naish, of the University of Portsmouth, decided to investigate whether or not giraffes could swim after Dr Naish took part in an online debate on the subject.

In previous work, Dr Henderson had created a digital model of a giraffe, and had also tested the buoyancy of various computer generated models of animals. The new study, published in the Journal of Theoretical Biology, examines what happened when scientists placed a 'digital giraffe' in 'digital water'. Dr Naish said: "Many previous studies have claimed that giraffes cannot swim and that they avoid water like the plague, even in an emergency, but we wanted to put the theory to the test in proper controlled experiments." Creating a digital giraffe involved numerous calculations on weight, mass, size, shape, lung capacity and centre of gravity.



Calculations were made to discover rotation dynamics, flotation dynamics and the external surface area of both a giraffe and - for control purposes - a horse. The authors found that a full-sized adult giraffe would become buoyant in 2.8metres of water. Giraffes can wade across bodies of water that are shallower. Dr Henderson said: "The idea that giraffes are poor waders or will not cross rivers is untrue and there are no obvious reasons why giraffes might be more prone to sinking than other animals." But after becoming buoyant, a giraffe would be unstable in the water due to its long, heavy legs, short body and long neck.

The unusual shape of the giraffe meant that it floated in a peculiar manner, with the long front limbs pulling the body downwards. This forced the neck to be held horizontally and mostly underneath the water surface, so the animal would have to hold its head upwards at an uncomfortable angle. Giraffes have other handicaps in the water. Horses tend to swim by trotting in the water, similar to the way they move on land. But giraffes move on land in an unusual way, moving their neck up and down in time with their limbs, and this important neck movement is not possible in the water. This means that giraffes are probably very poor swimmers.