The Conchological Society blog

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Those of us working on the Darwin Tree of Life (DToL) project based at the Marine Biological Association (MBA) are on a mission to collect and identify all Eukaryote species in the ocean surrounding Britain and Ireland.

Some of these are notoriously tricky to identify, so we often work with experts who know a lot about specific groups. Back in the summer of 2021 the DToL team left the MBA for Pembrokeshire, to join a team of keen experts from the Conchological Society in a marine mollusc hunt. 

Our first day found us wading through deep pools and into some dark caves, with Conch soc member Bas Payne. We were searching the walls for a tiny marine cave snail called Otina ovata, which tend to live above the line of barnacles and other invertebrates, on the smoother walls.

Otina ovata at first glance look like tiny limpets, but they have a lot less suction, coming off the walls easily. They’re so small you would easily miss them, but luckily we had Bas on our side and managed to collect a group of these teeny snails.

They then had a long journey back to our labs in Plymouth, but with the help of some cold packs and wet tissue paper they all made it. Once under the microscope the characters of these tiny gastropods really came through, they were so zippy it was hard to get a good picture, they seemed determined to explore every inch of the petri dish. We have found this is often the case with the smallest of animals, they might go completely unnoticed outside in their environment, but as soon as you look at them on their own scale they come alive in a totally different way.

Many of the things we find don’t have common names yet, as they are too small or haven’t had enough public interest. We think this is a bit of a shame, so we have been adding in common names whenever we can. In future, when people look up Otina ovata, they will be able to see that they are also called Bas’s cave snail, in honour of our hardworking snail expert who led us fearlessly into sea caves to find these, and many other gastropods for our project. 

Otina ovata, Bas’s cave snail under the microscope

Transporting some of these tiny snails is no mean feat, some of them are used to fluctuating temperatures and oxygen, but for others they live in such specific places that they aren’t used to constant changes and keeping the temperature and oxygen at the right level for such a tiny thing while on the road is not easy. Luckily most of our animals made it back alive, and we managed to process samples for 17 different species.

However, some of these snails were so small that we will have to wait for a little technological advancement so that we can actually get enough DNA for a read. The DToL project is pushing the science forward in leaps and bounds in that regard, and we don’t think it will be long until we have a completed sequence for these, and all the other tiny marine animals we find on our collection journey, but in the meantime they are safely stored on ice. A huge thank you to Simon, Bas, Rosemary and the other wonderful members of the Conchological Society who helped us find and identify so many precious creatures. You can read more about their amazing work on their website