ON THE WILD SIDE
Time to get a wiggle on
IT’S tadpole season – and as the resident amphibians start to come out of hibernation and get frisky, so too comes the spawn.
Then soon enough, the tadpoles. They are a delight to see for people of all ages, wiggling in the shallows of ponds and rain pools.
But tadpoles are rather weird. Imagine being born a wiggly little fishy lump before slowly growing legs, arms and lungs.
Herpetology is the study of all things amphibian and reptile.
Reptiles have scales and generally don’t need water to breed, while amphibians do need water and have wet skin instead of scales. Most amphibians are just as happy in the water as they are on land.
All of our amphibians need water in which to lay their eggs, and you can tell who laid them by what they look like. They all lay little black dots surrounded by clear jelly.
Frogspawn will be the one everyone has seen – massive lumpy clumps sometimes almost taking over entire bodies of water.
Toads lay their spawn in long strings or chains, usually deeper in the water, so are harder to see.
But the hardest to see are the newts, who glue individual eggs to underwater plants. All of these eggs hatch into tadpoles. Tadpole is a Middle English word meaning “toad head” or “round-headed toad” depending on who you ask.
They say that only about one in 50 will live to step on to land and even then as little as 1% could live long enough to breed.
Usually in the UK, once the tadpoles pop out of the eggs, it takes about 14 weeks for them to metamorphose, growing teeth, arms, legs and lungs. Yes, they have teeth – up to four rows in some species – so they have skeletons that can become fossils.
Tadpoles can control their own development. If their pond starts drying up, they grow everything quicker and leave. If there is lots of food and room, they can wait another few months.
Some rare smooth newts never turn into adults and stay babies for ever – a condition known as “neoteny”. And that is what the Mexican axolotl is – just a salamander that never left the water.