New abyssal ‘fishing’ worm discovered

An intriguing new species of deep-sea worm, Melinnopsis nathanieli, has been described from the dark, cold depths of the NE Atlantic, southwest of Ireland. 

The species was collected from the Porcupine Abyssal Plain Sustained Observatory (PAP-SO), a long-term scientific study site in the northeast Atlantic at nearly 5000m depth. The discovery was a collaboration between researchers at the National Oceanography Centre (NOC), the University of Southampton and the University of Portsmouth.

Previously described species from PAP-SO include octopuses, sea anemones, amphipods, sea cucumbers and sea pens. This is the first new polychaete worm (bristle worm) species described from the site for a decade.

Specimens from the historic Discovery Collections at NOC were examined using a range of techniques, including both morphological and genetic methods which enabled researchers to confirm this as a species new to science. The worm has been given a name with a special meaning – honouring NOC researcher Amanda Serpell-Stevens’ son, Nathaniel, as a surprise for his 21^st birthday!

Introducing Melinnopsis nathanieli 
In situ seabed images appear to show Melinnopsis nathanieli ‘fishing’ for food. The worm sticks out a long tentacle from its mouth, sweeps it through the water column and across the sediment surface picking up food particles, similar to a flyfisher casting for trout. 

Its tube, which stands upright in the sediment, can reach at least 30 cm in length and has a close association with anemones and ascidians (sea squirts). The tube acts as a hard substrate for these animals, raising them vertically into the stronger water flow above the sediment surface enabling them to trap more food.

Although the species of worm had been observed frequently in seabed photographs and collected in sampling surveys used to assess long-term environmental change at PAP-SO since sampling began there in the 1980s, it has remained a nameless mystery for decades.

Dr Laetitia Gunton, lead author of the study and teaching fellow at the University of Southampton, said: “This study is unique as it is very rare to be able to provide behavioural information in a deep-sea species description. This is the first time I have described a deep-sea species with in-situ images available. The vertical positioning of the worm’s tube in the sediment and mid-water ‘fishing’ technique is fascinating, I would never have expected the behaviour from studying the physical specimens alone.”

Naming this species by writing a formal description and observing its behaviour vastly improves understanding of biodiversity at this important long term monitoring site. This allows scientists to make better comparisons to other deep-sea locations around the world and understand deep-sea species’ unique ecological roles.

Dr Laetitia Gunton and Amanda Serpell-Stevens study the new species of deep-sea worm

The team will continue to ‘fish’ for new species and this research is the beginning of many more discoveries, not only specimens from the depths of PAP-SO, but also among the many treasures still to be revealed within the Discovery Collections. 

Dr Tammy Horton, co-author and manager of the Discovery Collections at NOC, said: “It is always wonderful to see new species being described from Discovery Collections materials, particularly when these are abundant, common species from our time series study site.”

Dr Andrew Gates, Principal Scientist for the PAP-SO, added: “Even after years of sustained observations at PAP-SO, the deep sea still surprises us. Describing a new species in a well-studied area shows just how much life in the deep ocean remains to be discovered.”

This project was supported by the Atlantic Climate and Environment Strategic Science (AtlantiS) programme and The Nippon Foundation-Nekton Ocean Census.