Tanystylum conirostre - An ammotheid sea spider (Pycnogonida images)

The specimen above was found on washing hydrozoan, bryozoan and kamptozoan covered Fucus serratus, Saw Wrack, on a low spring tide on the River Tamar at Ashtorre Rock, Saltash, Cornwall, SX4338058757. 13.09.22.

The Fucus serratus was mainly covered in the bryozoan Amathia sp.. The area where this species is found is especially biodiverse for an estuarine situation with fast flowing currents. The sea spider was one of 99 species reported after two days of searching and microscopy.

I am very grateful to Dr. Tobias Lehmann for validating this species, who commented it was a juvenile specimen due to the lack of development of the oviger.

On looking into this species further and its sparsity of records I have found the species also occurs in the NE Atlantic and that it can be found / collected on hydroid covered floats. P.E. King in his 1973 book 'Pycnogonids' states on page 38 that "An important factor in the distribution of some small species in the Atlantic appears to be Sargassum weed", he reports nine species are likely carried this way, six of them being recorded at Tortugas in the Florida Keys, whilst on the eastern side of the Atlantic the same species are found scattered from Norway to Cape Verde. Sargassum weed is not something that regularly turns up in the UK but plastic items covered in hydroids are abundant and these items are often to do with commercial fishing and include traps, pots, rope and floats. Similarly wood in the form of timber often washes up in the UK and can be covered in or contain (as with boring molluscs), a wealth of organisms including hydroids.

More natural spread also occurs as hydroids regularly coat pelagic Goose-neck and Buoy Barnacles, sea beans and algae such as Ascophyllum nodosum. The latter is commercially harvested in the USA and pieces regularly become hydroid, algae and diatoms covered prior to washing up in the UK, e.g. on the north coast of Cornwall.

It is therefore conceivable that we are possible dealing with an alien non-native species but potentially a species that could also be considered cosmopolitan because of its likely spread by natural process. That said this spread is encouraged and promoted by anthropogenic means and the increase of refuse that now drifts between nations and across oceans. It is therefore likely we will see an increase in the reporting of this species and similar species like it.

APHOTOMARINE

An educational resource dedicated mainly to the photography
and diversity of marine life that can be found in coastal waters
and intertidal areas of Great Britain and Ireland by David Fenwick.

APHOTOMARINE

An educational resource dedicated mainly to the photography and diversity of marine life that can be found in coastal waters and intertidal areas of Great Britain and Ireland by David Fenwick.

An educational resource dedicated mainly to the photography
and diversity of marine life that can be found in coastal waters
and intertidal areas of Great Britain and Ireland by David Fenwick.