Frogs come in nearly every colour of the rainbow - from the dull greens of British species, to the vivid yellows and reds of their tropical relatives.
But Japanese scientists have gone one step further than mother nature - and created a transparent frog.
The creature's see-through skin allows researchers to see details of its internal organs and blood vessels. They say this could bring huge benefits to medicine, making it easier and cheaper to study diseases such as cancer.
Professor Masayuki Sumida, who led the project at the Institute for Amphibian Biology at Hiroshima University, said scientists could look at the effect of drugs and chemicals on the frog's internal organs and blood vessels without the animals having to be killed and dissected.
'Because the frogs remain transparent from their birth to adulthood, organs of the same frog could be studied throughout,' he said. 'This is simple and cheap when studying, for instance, how certain chemicals influence bones.'
By attaching green fluorescent markers to a stretch of DNA and injecting it into the frog, researchers can also study the behaviour of genes in a living organism.
The transparent frog (pictured) is the offspring of common Japanese brown frogs. It was created through traditional selective breeding, rather than genetic modification, using wild frogs with a mutation that gives them pale skin.
By mating the palest frogs they could find and then breeding from their palest offspring the researchers were able to create the see-through strain.
The scientists say they plan to patent the technique but have yet to perfect the process. Only one in 16 frogs they breed has transparent skin and they have not succeeded in getting the transparent frogs to breed see-through offspring.
Most of the world's natural see-through creatures live underwater. Animals such as jellyfish, sea worms, sea snails and octopuses evolved transparency as a form of camouflage. In an environment where there are few hiding places, being see-through can give them an edge.