Magical creatures
AN APRECIATION OF TADPOLES
Getting bitten, stung, scratched and slimed defined my childhood experience of nature. However, taking risks that would terrify me now fuelled a lifelong interest in the living world. Each season would herald its own delights, but stumbling upon a spring pond frothing with frogspawn was always a highlight. What never struck me until I grew up is just how tough life in a pond could be, especially for a tadpole. In early spring, female frogs and toads rely on sheer numbers as a survival mechanism, laying up to 5,000 eggs. It’s no wonder the ancient Egyptians used the image of a tadpole in their hieroglyphic system to represent the number 100,000 – colossal numbers of tadpoles would have swamped the Nile.
The spawn of frogs and toads can quite easily be told apart: frogs lay their eggs in vast rafts, while toads’ are in long strings. Despite the strength in numbers, this army of spawn can be completely wiped out by a late cold snap. Droughts are equally catastrophic – if the water dries up before the eggs develop then it’s all over before it’s even started. Then there’s lack of light, decomposing fungi, anthropogenic pollutants and algal blooms to add into the mix. It really is a case of survival of the fittest… and of the luckiest.
If the spawn can avoid an untimely end for three weeks, the miracle of metamorphosis can commence.
And it truly is a miracle. When tadpoles first emerge, the remnants of the jelly from their egg remains inside their gut, sustaining them for the early days of their lives.
These legless, water-bound tadpoles are on the menu for fish, dragonfly larvae, water boatmen, newts, lizards, grass snakes, birds and even hedgehogs. As if that wasn’t hazardous enough, they also have their own siblings to add to their list of concerns as they can resort to cannibalism if food becomes scarce.
If they’re not gobbled up, frozen, suffocated or poisoned, they will grow strong enough to be able to swim and search for their own food: a plant-based diet of material filtered from the water. A month later, teeth begin to develop. Dip your finger into a writhing mass of speckled brown tadpoles and you might be treated to a mini-manicure as they gently nibble away on your skin.
The back legs then start to form, followed by the front ones. The wriggling tail is gradually absorbed into the body – a source of protein for this rapidly changing animal – while at the same time, skin grows over their gills, and lungs form to allow the froglet to breathe above water.
Around 14 weeks after hatching, those tiny jellyencased aquatic full stops have radically transformed into land-based, carnivorous, air-breathing froglets.
They are still fragile and vulnerable, so spare them a thought when summer comes around – they still have many hurdles to overcome before they reach maturity.
Consider lending them a hand by adding a pond to your garden, providing rocks and logs as habitat and avoiding slug pellets: we need to do all we can to ensure continuation of one of Earth’s most endearing, fascinating and accessible natural wonders.