British Wildlife Wiki

Last Year, one of our wiki contributiors Erik Paterson rescued some frog spawn from a frozen lake. He took photos of the development of the spawn and we are going to carry on where he left off!

Development of Frog Spawn[]


Day 0: The frogspawn has just been collected and so there are no signs of development yet.

Day 1: It has already began to change, the round, black larvae within the egg splitting in to two distinct parts and (when viewed at original size) tiny gills are already forming.

Day 2: The Embryos are now beginning to form their tails.

Day 3: Many of the embryos have now left the relative safety of their eggs, they will now absorb all the available nutrients from their eggs and take on their tadpole form, their tiny feathery gills are now functional and they are able to breathe in the water. They have also begun to move, curling themselves in to a ball and then stretching out, this will help to build muscle for when they require to swim, free of the spawn.

Day 4: Almost all of the Tadpoles have emerged from their eggs, most of them have fully developed gills now (which is clear in this image.) Their tails are becoming longer and growing gradually more compressed for swimming, some of these Tadpoles have even started to swim, albeit with varying degrees of success.

Day 5: Not much is happening, phenotypically, they look essentially the same as yesterday only their tails are slightly longer and more laterally compressed. They have generally began to swim now and should start feeding on fish food soon. Their newfound ability to swim is making getting photographs of them more difficult.

Day 6: Housekeeping. A lot of the old spawn is starting to break up and get 'funky' - as it decays, the bacteria use more & more of the oxygen in the water which would kill the tadpoles off so, i've removed the majority of the old spawn and added two of our native Water Snails which will eat the spawn, algae and excess food that the Tadpoles miss, the vacuum cleaners of the pond world - incidentally, I happened to have the water snails in an old paludarium on the balcony - i'm just that kinda guy.
As far as the tadpoles go, the gills are becoming slightly more feathery and they themselves are growing slightly larger.

Day 7: The weaker Tadpoles are beginning to die off, those that are stronger are losing their gills and breathing fresh air, they are also now mainly eating the fish food provided to them.
(do excuse the water, the fish food is making it slightly oily, more regular cleaning is required)

Day 8: All of the tadpoles have absorbed their gills now, coming to the surface to breathe air.

Day 9: The Tadpoles are starting to grow larger, soon, they will start to grow legs.

Day 10: The Tadpoles are starting to differ, those that hatched from their eggs first are much larger than those that hatched later, they are also beginning to change colour, they will turn brown now unlike the tadpoles of our other anuran, the Common Toad (Tadpoles of which remain smaller and stay black.) Tiny hind legs are beginning to form but it will be a few days before they are clearly visible.

Day 18: The tadpoles are getting much larger, turning brown and developing a golden brown speckling on the underside.

Day 20: Their colours are developing nicely, a specimen appears mottled with light golden brown and green.

Life Cycle of a Frog[]

Coming soon!