Scientists believe the answer lies in the animals’ fast metabolism. To help them fly, fruit bats require up to 20% more calories than a non-flying mammal. This speedy metabolism raises the level of free radicals in their blood, which have the potential to damage their DNA.
To prevent this from happening, a bat’s immune system is constantly in overdrive. It cleans up the dangerous molecules – including potentially deadly viruses. Since their immune system functions so well, the animals don’t get sick. The virus multiplies in their bodies and they pass it onto their offspring – but they never develop symptoms.
FRUIT BATS – Like all bats, fruit bats belong to the Chiroptera order. After rodents, these are the most diverse species of mammals in existence. They can weigh up to one kilo and have a maximum wingspan of 1.7 metres. Unlike other types of bats, most fruit bats do not navigate using echolocation. Instead, they have outstanding vision and an excellent sense of smell. Their diet consists mainly of fruit, flowers, pollen, nectar and insects.
The African straw-coloured fruit bat shown here has a maximum head-to-toe length of just 20 centimetres and a maximum wingspan of 75 centimetres. It has a dog-like head and a good sense of smell with which to sniff out ripe fruits. The bat also feeds on nectar, and thus plays an important role in the pollination of plants – 40% of trees in the world’s rainforests would be unable to produce fruit without their help.
