The tadpole shrimp Triops cancriformis has been found in the Caerlaverock nature reserve in Dumfriesshire, Scotland. It is considered to be possibly the oldest living species in the world, because it has remained nearly unchanged for an estimated 220 million years. (Another reference states tadpole shrimp may have been living for 300 million years.)
Scientist Larry Griffin who has studied the rare shrimp, said, “Triops matures rapidly and produces hundreds of eggs in just a couple of weeks. The pond they live in may dry out, but the eggs can survive in the mud for many years.”
Not only are the shrimp unique for having survived several major extinctions, they also can have both male and female reproductive parts so just one can generate a new colony. Tadpole shrimp live in seasonal, freshwater ponds. Their eggs are very tough. They can resist high temperatures (almost boiling), dryness and even consumption by birds. It is thought they also can remain in a dormant state for years, or even centuries until favorable conditions occur, and then they hatch. Tadpole shrimp have outlived dinosaurs, trilobites and mammoths. They are endangered and protected by law in Scotland.
Tadpole Shrimp Video