Studying frogs, and the dangers they face worldwide

By Anita Poehlig Feb 21, 2011, 13:05 GMT

Frogs © Flickr/g_kovacs

Braunschweig, Germany - Some frogs can weigh almost three kilograms while others are hardly bigger than a thumbnail. Some are an inconspicuous grey while others glow in beautiful colours.

About 6,000 types of frog are known to science but many of them are now on the brink of extinction.

Miguel Vences, a professor at the Technical University of Braunschweig in Germany, is an expert in the field of amphibians.

'Frogs were hopping around when dinosaurs walked the planet,' says Vences, who has gained a name for himself around the world for his work. Frogs have existed on earth for about 250 million years but in some countries their numbers are under serious threat.

'In France and Belgium, but also in the US, frogs legs can be found as a delicacy on menus and many frog habitats in Asia have been sacrificed for human consumption,' says the biologist. In China and other far eastern countries frogs are a part of the staple diet.

'Famine in Africa has meant that frogs are a frequent form of nutrition,' says Vences. Estimates suggest that as many as a billion frogs are killed and eaten by humans every year.

In addition to the threat posed by people, frogs are also at risk from a fatal skin fungus. 'Rainforests where you could hear frogs calling everywhere in 2009 are now silent,' according to Vences.

It's not yet clear whether the Chytrid fungus is responsible or whether other environmental factors have led to a decline in numbers. 'The fungus also exists in Germany but it appears our amphibians are not falling victim to as great an extent.'

'As a child I would look for frogs in pools,' recalls Vences. At that time many varieties of frog known to science today were unheard of. Vences and his colleague Frank Glaw have discovered about 100 new species between them.

Both men have been carrying out research work in rainforests since the 1980s, mainly on Madagascar. In one of their books they list 350 species that only live on the island.

The sheer variety of frogs is amazing and many of them have different ways to reproduce.

'Some give birth to self-sufficient frogs while others lay eggs. Some swallow the eggs and incubate them inside their stomachs,' says Vences. One type of frog lays an individual tadpole in a water-filled leaf and feeds it with unfertilised eggs.

'All of these amazing types of behaviour are threatened by extinction,' he says.

'Amphibians have survived so long on earth they have become an important study group for evolution theory,' according to Vences. They are also of interest to medicine as certain types of painkillers and antibiotics can be found on their skin.

'There's still plenty to discover about frogs.' One thing is sure, however: a kiss won't turn a frog into a prince.