According to Official Guinness Records,
The oldest living creature is the Triops cancriformis, or tadpole shrimps, which are said to be the oldest pedigree of any living creature and fossil evidence suggests that they have hardly changed in the 200 million years they have existed.
The tadpole shrimps are classed as endangered in the UK, but 2 colonies were found alive and well in July 2010 in the Caerlaverock nature reserve on the English coast line.
For a complete list of 2010 records, please visit 2010 Guinness Records in United Kingdom.