European tadpole shrimp

General information

The European tadpole shrimp (Triops cancriformis) is one of the oldest species on Earth, with fossil evidence dating back around 220 million years, earning it the title of a true “living fossil.” Although it is still fairly widespread across parts of Britain, in the UK it is now restricted to just two known ponds, one near the Solway Firth in Scotland and the other in a temporary pool in the New Forest, and is therefore considered endangered here.

Perfectly adapted to life in short-lived pools, tadpole shrimp have an incredibly fast-paced life cycle: they must hatch, grow, mature, and reproduce before their habitat dries out, which means they need to consume around 40% of their body weight every day. Their eggs are equally remarkable, entering a dormant state called diapause that can last up to 27 years; these tough eggs can even survive being eaten by birds or fish, which may help the species spread between isolated water bodies. Unlike many modern aquatic animals, Triops do not have true gills, but instead breathe through primitive, leaf-like extensions on their legs, adding to the ancient and unusual nature of this extraordinary crustacean.