200 near-extinct tadpole shrimps hatch out at WWT Caerlaverock

22/05/2009 08:42:26 Tadpole shrimps, oldest living creature on the planet, bred in captivity
May 2009. WWT has taken an important step in the conservation of the UK's near-extinct tadpole shrimp population, hatching an amazing 200 tank bred triops at its reserve at Caerlaverock , Scotland, at the first attempt.

The tadpole shrimp (Triops cancriformis) is a living fossil, thought to be the oldest living creature on the planet. Resembling a small horseshoe crab, it was recorded at least 220 million years ago in the Triassic period, even before dinosaurs roamed the earth. A colony does exist in a single pool in the New Forest, but another was found at WWT Caerlaverock last year, during our particularly wet August.

Live for just 12 days - 4 months
Triops live for between just 12 days and four months, but lay eggs which can lie dormant in dried pools for decades. In an attempt to safeguard the population, last September WWT collected four adult hermaphrodite females from the colony at Caerlaverock, under licence from Scottish Natural Heritage. They were kept in a three foot fish tank filled with a muddy substrate to allow them to forage and ultimately dig their egg pits before they died.

Beginners luck - Accelerated hatching
WWT researcher Dr Larry Griffin explained: "This was the first time we had ever done this so we weren't sure whether or not it would work. The tank was dried down over several weeks and the mud divided up into portions in which it was hoped there would be 100 or so eggs laid. The mud samples were then bagged up and put in the freezer for a few days, before being removed, placed in a small tank and wetted up again at about 20 degrees. It was really exciting because after only 48 hours the tiny nymphs could be seen swimming about the tank with the orange hatched eggs floating on the surface, despite being only 1mm in diameter."

WWT are currently working with WildCru to investigate other historic sites, and will look into the species' history, ecology and requirements in more detail. Dr Griffin said: "In theory, the unhatched eggs in the mud samples here at Caerlaverock  could remain viable on the shelf for anything from two to three decades and as such will remain an extremely effective ex situ conservation tool for the preservation of this species, much as a seed bank does for plants."