Ranasmurfin. Now there’s a name which could belong to a fairy tale, much like Rumpelstiltskin – the name of the goblin who, in return for several favours, spun straw into gold for a forlorn young woman. Ranasmurfin spins nothing, although it is itself woven into a soft mass – or ‘biofoam’ – in which nest the eggs of the Java whipping frog, common in eastern Asia. This particular biofoam is whipped up both by the male and the female frog; it not only protects their progeny from predators and harsh environmental conditions but also offers a favourable micro-environment in which they can flourish. What is more, the nests are positioned just above water. Hence, once the eggs have hatched, all the tadpoles have to do is drop into their new habitat below!
The biofoam has a creamy colour to begin with, and then turns blue within a few hours. It owes its blue colour to ranasmurfin, a protein which has a zinc ion in its middle. It is believed that it is the zinc along with other molecules that give the biofoam its blue colour. Ranasmurfin is thought to have mechanical as well as adhesive properties but why is it blue? No one really knows. It could just be a byproduct. Or it could have something to do with protecting the eggs from harmful sun rays. On the other hand, perhaps there is no real reason for it being blue. Perhaps Nature hasn’t given it a thought yet – no one has ever tried to find the point of the colours of a rainbow.