Although I have dived the North Sea for over fifty years, for the first time in 2009 I came across this unusual hyrdomedusa, Tima bairdi. And it wasn't just one I saw but maybe thirty over a two week period. Other divers were also reporting them in good numbers. Some had long tentacles extended as here but mostly they were retracted. I have been unable to find out much about them except the maximum diameter is supposed to be 65mms. Clearly, many of those I saw exceeded this figure. I would estimate the largest at more than twice this figure.
Sometimes incorrectly called Tima bairdii.
St. Abbs Marine Reserve, Berwickshire. E. Scotland