The tadpole shrimp is a relative of one of the oldest known animal species in the world – a species with fossils dating back 220 million years. The reason it has survived so long can be attributed to the species’ very clever biology.

Firstly, all tadpole shrimps in the UK are self-fertile female hermaphrodites, meaning a population can start from just one hatched egg.

Secondly, tadpole shrimps live in seasonal pools which dry out in the summer. These pools may only last a few weeks before drying out, and then it may be years or even decades before the water returns. When the pools dry out all predators and competitors are killed off.

Tadpole shrimps, however, have adapted to these inhospitable conditions. They have very rapid development, maturing from an egg to adulthood in just two to three weeks. This means they are able to hatch from an egg and produce the beginnings of the next generation before their pool dries out, all in the space of a few weeks.

But what happens to these eggs when the pool dries out? When tadpole shrimp eggs are laid a proportion of the eggs hatch, and the rest go into diapause – this means the eggs dry out and their development is stopped. In diapause tadpole shrimp eggs are very durable and can survive up to an incredible 27 years. The eggs can also endure extreme temperatures, immersion in salt water, and can be eaten and excreted by an animal without harm! Once these eggs are rehydrated and the environmental conditions are right, the diapause will end and the eggs will hatch forming a new generation of shrimps.