Styela plicata

David Kipling Close-up for Becky Hitchin

Becky Hitchin it's not Styela plicata, is it?

David Kipling I have some live specimens still in a bucket in the garage, I'll take some pics tomorrow when it is light.

Erling Svensen Here is a picture like they normally live together in colonies.

Erling Svensen I do not think they are juveniles. They sit in colonies, but I can be wrong.

Rob Spray Ours look more like this: http://www.1townhouses.co.uk/pelagicpixels/2009/EastJuly09/Sunday%20afternoon%20Vera/slides/P7052393.htm

Rob Spray Maybe this will embed better: http://www.1townhouses.co.uk/pelagicpixels/2009/EastJuly09/Sunday%20afternoon%20Vera/slides/P7052393.jpg

David Kipling There's also Parajassa pelagica, another tube-building critter, although I think the wavy arms at the front are different: http://species-identification.org/species.php?species_group=crustacea&id=369

David Kipling Yeah, there's loads round the corner to the right at Martin's haven, I've got pics somewhere. Sarah'll remember the name.

David Kipling (you should have swum further!)

Marco Faasse It is true that these look a bit different from Jassa Erling Svensen. Their second antennae are not that robust and they are held straight (usually downcurved in Jassa). Furthermore their backs seem banded, while the pattern on Jassa is more irregular. As Dawn Watson says in Jassa sizes tend to be segregated, but often you see a few larger ones between the small. It is also true that the juveniles look different from adults, with less robust and less densely haired second antennae. ID of juveniles is difficult and ID of adults not showing their legs as well. It's almost impossible to give a name to specimens in their tube as in your photo, Erling. There are three or more Jassa species in the NE Atlantic, there's Parajassa as David Kipling says, there's Microjassa, there's Ischyrocerus and there's still more ... For a certain ID it's necessary to collect or to take a good picture of an animal ouside of its tube. I would be glad to collect and ID some.

George Brown Photis longicaula. The more I look the more I find.

Erling Svensen Sorry George, but my brain do not understand Photis longicaula. Is this a name on an amphipode???

David Kipling Photis longicaudata: http://data.nbn.org.uk/gridMap/gridMap.jsp?allDs=1&srchSpKey=NBNSYS0000177164

David Kipling I think longicaudata translates as long tail?

Marco Faasse Photis longicaudata is another tube-building amphipod that filters the seawater with its antennae. It builds its tubes in tight colonies around the tip of Cerianthus tubes ... I think there's a pdf of a scientific article about its habits on the web. Its hindmost uropod or "tailleg" is longer than in its closest relative -> longicaudata David Kipling :-)

Marco Faasse Can't find a pdf; only have a photocopy ...

David Kipling I'm surprised the waters round Pembrokeshire aren't crystal-clear with all these ascidians, sponges, anemones, bivalves, hydroids, bryozoans and amphipods filtering everything from the water column! I wonder which make the greatest different to water quality (as in sediment/phytoplankton load)?

Marco Faasse Maybe you should turn it the other way around: that all those filter feeders abound especially there where there is so much to filter that they can't cope with it.

Marco Faasse Now I see that Dawn Watson already mentioned a remark of George Brown about the habits of Photis longicaudata ...

David Kipling Absolutely! The same was true for Raja Ampat, where many places were actually quite low-viz because of the plankton/sediment load but I have never seen so many ascidians in one place...

Marco Faasse But you are right David Kipling that those masses of filter feeders do have an influence on suspended matter. In the relatively small water mass of the Oosterschelde we see that viz improves very quickly when influx of suspended matter stops for a while. Then the mussels and ascidians do their job.

David Kipling Lisa Draughon did a thesis on using Styela plicata for bioremediation of sediment-rich waters (basically floating balls pre-covered with ascidians thrown into the water ... clears them up a treat since each animal filters > 3l/hr of water).

Marco Faasse And zebra mussels have been used in fresh water to improve viz.