Life cycle of a frog: how do amphibians reproduce?
Spring is the perfect time of year to start spotting some of our native amphibians. Breeding season is upon them, and they're clustering around ponds in hope of finding a mate.
In the winter months, our frogs, toads and newts were hibernating in compost heaps, piles of dead wood or at the bottom of ponds. But as temperatures warm, they wake up and re-emerge.
Around this time of year, you'll be able to see some of your local frogs, toads and newts as they congregate around ponds to mate. This process kicks off a new rotation of their lifecycle.
The breeding and egg-laying process
As the amphibians gather, every male attempts to claim a female. For frogs and toads, the males will clamber on top of the female in shallow areas of water. This causes the female to lay her eggs - up to 5,000 of them! These are promptly fertilised by the male.
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Newts do it differently, with the male having to prove his worth by shaking his tail. If the female is suitably impressed, he's allowed to mate with her. He presents her with a sperm-filled bubble, which she picks up to fertilise her eggs. After a few days, she starts to lay up to 12 a day. She may lay as many as 400 eggs in a season, each placed carefully under the leaves of aquatic plants.
In all amphibians, eggs hatch after one to three weeks depending on water temperature. The resulting tadpoles initially live off the yolk that stays with them, but after a few days, they need to feed. Frog and toad tadpoles feed on plant matter, whilst newt tadpoles eat microorganisms like freshwater plankton.
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Young amphibians change fast
Tadpoles have to undergo huge physiological changes to survive on land. This physical development process is called metamorphosis. The external gills become internalised, and their lungs develop.
Eventually, the gill structures entirely vanish. This happens much earlier in frogs and toads than in newts. Limbs also form in this stage. Hind limbs are first in frogs and toads; front limbs appear first in newts.
Frogs and toads continue to grow and change as their lifestyle completely changes, but newts stay more constant.