Once a month we will be sharing a marine species reported via the Fair Isle Marine WhatsApp group. This group is a space for community members and visitors to the isle to share any interesting marine finds. These reports also contribute to marine species records for Fair Isle to help monitor changes in biodiversity.
For January, we have this crystal jellyfish found by David Parnaby at South Haven. Crystal jellyfish are from the genus Aequorea and are pelagic organisms meaning they live in the water column in open oceans. It’s easy to see how they get their common name as they are relatively transparent creatures. Crystal jellyfish have a large number of tentacles and are known to have bioluminescent properties, meaning they can emit light, a natural phenomenon termed locally as ‘mareel’.
We think this species may possibly be Aequorea vitrina which is more commonly found along British shores… However, this genus is particularly difficult to identify down to species level as a lot of the species have very similar features and morphologies. So, if there are any cnidaria experts out there who might be able to help us confirm please get in touch! 
David Parnaby
Crystal jellyfish, Aequorea sp. South Haven, Fair Isle