This rather strange way of demonstrating a biological sample is a resin block embedded with examples of the stages of a frog’s lifecycle.

A frog takes about 3 months to become fully grown and develop all the organs that allow it to breathe on land and in the water. You can see what dramatic changes happen to a frog in this first year.

The female frog lays thousands of eggs in a pond, some of which are successfully fertilised by the male frog. There is a lot of croaking in the pond during this time as this is the way that the adult male frog attracts the female for mating. The eggs are in a jelly-like clump called frogspawn. Inside the tiny black egg the frog starts growing and the first things that form are the gills, the feathery bits, and the tail, which you can see if you look carefully at the second specimen. After between 9 – 14 days, the tadpole, the baby frog, is ready to hatch out and it takes about a day for it to work its way out of the egg. You can see how tiny this tadpole is in the third specimen. The tadpole can breathe underwater but many get eaten before they have a chance to grow.

After about 4 weeks the teeth and the lungs begin to grow and the tadpole’s gills are covered by skin. After 6 weeks the back legs start to grow followed by the front ones and the tadpole becomes a froglet, part tadpole and part frog. In the fourth specimen you can see the back legs, but by the fifth the tadpole has both back and front legs and looks like a mini frog. The tail is shorter and the mouth is wider. This is now about 14 weeks after conception. 

Once the lungs are formed then the frog can live on land and in the pond. A fully grown frog is 10 times bigger than when it first comes out of the pond though it is still smaller than an adult’s hand.