Tuesday, 7 October 2014

Celtic sea slug hotel Rediscovered at Fowey

Have you seen a Celtic sea slug before?
Also know as the licorice seaslug, Onchidella celtica is a tiny black (sometimes greyish) sea slug that grows to a maximum size of 2cm and can be found grazing on the mid to upper shore. If you haven't seen one you are in good company, most people haven't heard of them and although they are common in some places around Cornwall many local marine biologists haven't even seen one! 
What makes them special?
They are very rare - only being found in a handful of locations in the UK. On Cornwall's North coast they can be found in large numbers between Holywell bay and Hartland point (we saw lots on the honeycomb worm reefs at Northcott mouth and at Polzeath see the previous blog entries!). But on the south Coast they are found only rare small colonies spread out along the coast. This summer I was lucky to see them for my first time ever on the south coast. On our Shoresearch survey of Fowey's Readymoney cove we were joined by Sarah Matthews. Sarah is the daughter of Gillian Matthews who was a well known naturalist who studied Chitons and other molluscs. Gillian spent hundreds of hours searching the coves and rocks around her home town of Fowey looking for the Celtic sea slug and eventually found a colony living on the north face of an upstanding rock near Readymoney cove. The strange thing is she was unable to find them living anywhere else in the area but on this one rock there lived a colony numbering tens, possibly more. 
Gillian sadly died many years ago but the secret of the Fowey Celtic Sea slug hotel was passed down to Sarah and on our Shoresearch at Fowey we were privileged to be shown the exact spot and .. sure enough saw over 30 of these small but awesome sea slugs! They haven't been recorded here since the 1980's but they were still there, happily grazing the rocks and enjoying the shade the north face of the rock provides. 
Unlike to normal sea slugs which have gills - Celtic sea slugs are actually pulmonate gastropods related to land slugs and snails. instead of gills they have a lung that means they are much happier out of water breathing air. when the tide falls they leave their crevices and feed on tiny algae plants growing on the rocks which they scrape off with their rasp like radula. They will only be out and about for a limited time as on a hot day they run the risk of being dried out so en mass they will suddenly all disappear back into small crevices to hide. 
When the tide comes back in these tiny warty skinned land lubbers stay in their bolt holes away from predators and wait for the tide to fall again. During this time they obviously cant use their lungs so it is most likely they are absorbing oxygen through their skin. 
They really are cool little guys and I felt really privileged to have seen their Fowey home!   

Sarah and the Sea slug hotel! Location secret! 
We also had a fantastic Shoresearch - Readymoney was teeming with life! There were lots of common sea stars under every rock, and as always we were amazed by the quantity and diversity of life on this very special shore!
Leptostracean (hooded shrimp) a small crustacean that is very under recorded. there is alot of argument over the classification of this group so I can only go so far as to say its Nebalia spp

Common sea star

Sally, Ryan and John carrying out a quadrat survey

Lineatus ruber a nemertean worm - can you see the eye spots?

A nice red sea weed that we had fun trying to identify - I think its Rhodomela cofervoides  

Thanks to all the volunteers but Shoresearch regulars and Friends of the Fowey Estuary who turned out and took part!
New recruits Nick and Jon with a Rissos Crab

My favourite crab photo of the year so far Xantho pilipes , Rissos Crab

Dynamene bidentata  an isopod 

Thursday, 25 September 2014

Polzeath and the Pool of dreams

Well first we had the 'Cave of Dreams' (at Fistral), then we had the 'Rock of Dreams' (Looe), and now we have the 'Pool of Dreams' found on our Cornwall Wildlife Trust Shoresearch survey at Polzeath on one of the lowest tides I have ever witnessed on this amazing shore.
As you can see from this photo our transect went down onto rocky kelp covered reefs that would normally be well covered by the w

ater and dangerously close to the surf. However on the day of our survey, 9th September 2014, we were lucky to have bright sunshine, high air pressure holding the water down and absolutely zero surf!! In this seaweed smothered shallow but pebbly pool we found an incredible diversity of marine life! Once again highlighting how fascinating rockpools can be in Cornwall!

As our quadrat landed on the pool we began to move the seaweeds and straight away spotted small tadpole like fish swimming away. This is a species that is only rarely recorded and one that I got extra specially excited about!!  Montagu's sea snail - this was named after Victorian naturalist George Montagu. You can see how it got its name as it can look more like a snail than a fish. When its not swimming it often curls up and using its pelvic fins as a sucker is able to hold tight. After a lot of frustrating fishing I finally caught one specimen from the pool! and here it is..

Also found in the pool of dreams -
One graceful sea spider
one Hairy crab
one large isopod Ideotea baltica
Lots of blue rayed limpets
Squat lobster x1
Hermit crabs x4
Saddle oysters
five bearded rockling x1
Velvet swimming crab x1
Shanny x1
Montagus sea snail x5
Sea scorpion x 1
Sea spider


It was great to see Rosie Ellis again back from her travels and volunteering again with the National Trust. Rosie's eagle eyes allowed her to find a very well camouflaged crustacean. A very rare Gibbs spider crab Pisa armata. This has only been recorded a handful of times in Cornwall with a few recent records found by fishermen off Newquay. You can tell by the knobbly surface of the carapace that it is this and not the similar Eurynome aspersa.
Gibb's spider crab Pisa armata photo by Matt Slater

This guy was covered in colonial seaquirts and bryozoans ! 

 closeup of the Gibb's Spider crab Pisa armata. Photo by Matt Slater

Sadly no stalked jellyfish this time in the usual spot! 

Laura was well chuffed with her find! 

A beautiful decorator crab - Macropodia rostrata

Laura's dog lends a hand with the transect

In Polzeath the star ascidians are all this amazing orange/yellow colour!

Clionia cellata - booring sponge

Monday, 22 September 2014

Looe Shoresearch - the ultimate rock

On this years survey of Hannafore point, Looe. Shoresearch volunteers were amazed, on lifting a large flat rock, to find nearly all of the lower shore animals you would expect to find on the shore under one rock!
the total number of animal species found was 21.
here is the list;

Shore rockling x4
Velvet crabs x 4
Shanny x1 (large)
Broad clawed porcelain crabs x8
Athanas nitescence (boy racer shrimps) x 8
Bootlace worm (Britains longest animal species) x1m (juvenile)
Scale worm x1
Worm pipefish x 4
Montagu's crab x 4
Longhorned porcelain crab x4
Squat lobster (Galathea squamifera)x 3
Star ascidian 1x colony
Strawberry ascidian (Aplidium proliferum)
Sea lemon x2
Hermit crab x1
pale beige breadcrumb sponge Halichondria panicea x1
Keel worms *30
Cthalamus and Semibalanus barnacles x 400 (ish)
Volcano barnacles x 30 (ish)
Spirorbis worms x 300 (ish)
Risso's Crab x 1

Grand total  21 species
Rob lifts the rock of Dreams
Individual animals 797!!

Squat Lobster Galathea squamifera

Shore Rockling (note 3 barbels around mouth)
Shanny - photo Matt Slater

Broad Clawed porcelain Crab Porcellana platycheles

Long horned porcelain crab Pisidia longicornis

Breadcrumb sponge Halichondria panicea

Montagu's Crab

The rest of the survey went very well too! We decided to carry out a transect survey along a long gully  so that it can easily be repeated in future.  Heather (www.cornishrockpools.com)  did a walkover survey in the lagoon and found stalked jellies among the eel grass! On the extreme lower shore we also found a really cool chameleon prawn. Thanks to Amelia, Micky, Cheryl, Rob, Heather and Louis, John and Jasmina who all turned out to help! It was a great day.  

Chameleon prawn Hippolyte varians - by Matt Slater

Stalked Jellyfish Lecernariopsis campanlata -Heather Buttinvant

The tide flooded in incredibly rapidly! 

Shorecrabs Carcinus maenas - its a crab eats crab world out there! 

Friday, 19 September 2014

Stars of the shore

Star Ascidians - Botryllus shlosseri 
These amazing creatures are relatively common on Cornish shores but they come in an incredible variety of beautiful colours and forms. Close up photography on our shoresearch surveys this September and over the years have produced some incredible images of these beautiful communal animals whose colours rival any tropical corals.
Gold arrows - found at Hannafore Looe Sept 2014 - Photo Matt Slater
Golden Star ascidian found growing on the stipe of a bushy Cystoceira seaweed, Prisk Cove, Helford September 2014 - photo by Matt Slater

Purple and white -  Marazion night rockpooling 2014 - Photo by Matt Slater

Yellow Star ascidians found at Poleath 2012 Shoresearch - Photo Matt Slater

Sometimes star ascidians carpet overhangs and continue to grow - in this slow motion dripping effect! Photographed at Polzeath during September Shoresearch 2014- Photo Matt Slater

 Star ascidians are colonial sea squirts that live by filtering sea water and removing plankton
Unlike most sea squirts which are solitary creatures star ascidians grow in large colonies in which many individuals (zooids) are joined together in a soft rubbery layer (test) attached rock or seaweed. Look closely at the colony and you will see that 3 - 12 individual squirts are arranged in a circle. Sea squirts are a sack like creature with an inhalent opening through which they draw plankton rich water and an exhalent opening through which filtered water and faeces pass. In the case of a star ascidian each squirt has its own inhalent opening but all of its neighbors share the same communal exhalent opening. Taking communal living to an extreme!

Star ascidian growing on seaweed Hannafore Lagoon 2013 september Shoresearch - Photo Matt Slater
Star ascidians are rubbery and beautiful but they do have their predators! Cowries feed on them by squirting digestive juices into them and then sucking out the juice! Look for cowries in the same habitat as star ascidians - over hanging rocks and boulders on the extreme low shore (only exposed on a spring tide!)
Cowrie, Trivia Monacha, photographed on the shore at Battery Rocks Penzance by Matt Slater

5 days, 62 volunteers and the largest spring tides of the Year- Shoresearch Week Goes OFF!

Thanks to all who came and joined me in my marathon 5 days of frantic shoresearching which included, Timed species searches, walkovers, Biotope Transect surveys and Quadrat surveys at all five of Cornwall's Voluntary Marine Conservation Areas. It has been an epic week- each day I have shared my favorite photos on Facebook but I plan to use the Blog to tell some of the stories of the week. Over the next few days I plan to upload my highlights of the week - a week I will certainly remember for a long time, not just for the incredible creatures we found, but for the incredible weather, the low tides, the lack of swell and for the incredible team of volunteers who shared in the experience, really helped me out and made it a really fun week!

me in action!
Nick and John 
Rob and the rock of dreams - more to follow..

This is the calmest and lowest I have ever seen the sea at Polzeath in three years of September surveys 

knees and backs were aching at the end of this week but we were all buzzing from having been privileged to have seen the sights we saw!

Rosie and the find of the day - can you spot him... more details to follow in the next posts!