Amgueddfa Cymru — National Museum Wales

Home

Deep beneath the ocean surface, where no sunlight can penetrate, there are areas so hot, volatile and toxic that it's hard to believe life can exist...but it does, and often in abundance. It is exactly this kind of hostile environment that one of our most recent natural history acquisitions came from, a spectacular marine snail called the 'scaly-foot gastropod', or for those of you who like Greek and Latin, Chrysomallon squamiferum Chen, Linse, Copley & Rogers, 2015 (fig. 1). It comes from depths of 2785m, living on the edge of hydrothermal vents and black smokers that reach temperatures of 300-400°C. This is certainly not your average snail...

Under armour and ready for battle

It was in 2000 that the first hydrothermal vent field was discovered in the Indian Ocean, known as Kairei field, and a year on that Woods Hole surveyed the area in the RV Knorr 162-13 and encountered this new species. It was immediately obvious that something unique had been discovered. The 'foot' of this snail, which is the fleshy soft part that snails move around on, displayed hundreds of hardened tags, almost like an armour. These tags are called sclerites; fleshy in the centre and hard on the exterior due to a layer of conchiolin (a protein secreted as a part of shell formation) covered by a layer of iron sulphide that gives it a black metallic appearance (fig. 2). The iron sulphide exists in two forms in the snail: greigite, which is highly magnetic, and pyrite, which is commonly known as fool's gold. The presence of the metallic sclerites is not totally understood but Suzuki et al. at the Extremobiosphere Research Center in Japan suggest the snail may control the mineralization of the iron sulphides for protection from crab predation or perhaps for detoxification purposes.

Completely unique is that the iron sulphide is also found in the snails' shell, so this was the first discovery of an animal with iron sulphide in its skeleton (fig. 3). Underneath the metallic exterior there is a thick but softer organic layer which covers the hard calcium carbonate shell that most marine snails have. So unusual is this triple layering in the shell, in both its chemical make-up and mechanism, that some scientists consider it to offer extensive protection and think it may be used as inspiration for man-made armour in the future.

New vent fields, new discoveries

The iron and sulphide found in the scaly-foot gastropods at the Kairei field comes from the mineral rich waters expelled from the hydrothermal vents and black smokers. Different vents do, however, have different mineral compositions. Nevertheless, it was still of great surprise when in 2009 the Solitaire field was discovered in the Indian Ocean and living on it was a different colour form of the scaly-foot gastropod; this time displaying a brown shell and cream coloured sclerites, both completely lacking the iron sulphide coating. Genetic testing by Nakamura et al. at the Precambrian Ecosystem Laboratory in Japan confirmed in 2012 that they are the same species and also that the sclerites of the iron-lacking form were in fact mechanically stronger. Then, in 2011, yet another population of the black scaly-foot gastropod was found in great abundance at the Longqi field, another new discovery for the Indian Ocean, and this is where the two specimens deposited at this museum came from. Figure 4 shows snails from the three different vent populations.

The heart of a dragon

The external features of this snail are certainly spectacular and strange, but taking a look inside shows that the theme continues there. It is of no surprise that this snail has special adaptations to live in such a toxic and harsh environment; survival in such a place certainly requires an evolutionary helping hand. Similarly to other species living on black smokers and close to vent effluents it has evolved a symbiotic relationship with bacteria living inside its body. These bacteria supply the snail with most of its nutrition and to accommodate them the snail has developed a massive oesophageal gland, taking up over 9% of its body mass! In turn the snail needs to keep the bacteria alive and so has also developed a huge circulatory system, including a supersized heart, to supply the oesophageal gland with enough oxygen. It's a win-win situation, or perhaps a deal made in Hell!

What's in a name?

Although it was discovered 14 years ago it is only this year that the scaly-foot gastropod was officially christened Chrysomallon squamiferum by Chong Chen of Oxford University and his associates. This snail is so different to any others known that Chen et al. needed to describe a new genus to put this new species in. The genus name Chrysomallon means 'golden fleece', giving reference to the metallic coating often containing fool's gold. The species name squamiferum means 'scale-bearing', making obvious reference to the sclerites covering the foot of the snail. The process of describing new species also means that a specimen (holotype) or a series of specimens (holotype and paratypes) need to be selected as representatives of the species and placed in museum collections, and that is where we come in! The two specimens we have been donated are a part of this incredibly important 'type' series. They even came with a note telling us to store them in 100% alcohol as any water in the preservative would cause them to rust over time. Rusting is certainly not a conservation issue we usually have to consider with our mollusc collections!

Back at the museum

This is not the first addition of molluscs from deep sea hydrothermal vents to our collections. With resident bivalve researchers working here we already house material that has been described by our experts from such environments, in addition to other extreme marine environments. Some are from the oil seeps off Louisiana in the Gulf of Mexico, the mud volcanoes in the Gulf of Cadiz or methane seeps off Chile. Others are from hydrothermal vents on the Northern Mid-Atlantic Ridge and hydrothermal springs in the Cascadia Basin of the NE Pacific. Perhaps the strangest place that one of our new species was described from was the wreck of the sunken ship Francois Vieljeux which contained organic cargo containing sacks of beans, sunflower seeds and bales of sisal twine. Over time the rotting cargo produced a sulphur rich environment that attracted animals able to exploit it, including the bivalve Spinaxinus sentosus Oliver & Holmes (fig. 5). Amazing.

When you think that only 160 years ago much of the scientific community embraced Edward Forbe's 'azoic theory', that life could not exist beyond 550m, our knowledge and understanding of the sea has really come on a very long way. Nevertheless, there will always be more waiting to be discovered.

If you want to learn more about our collections follow us on Twitter @CardiffCurator

References:

Chen, C., Copley, J. T., Linse, K., Rogers, A. D. and Sigwart, J. (2014). Abstract from Seventh Congress of the European Malacological Societies. Edited by White, T. S.

Chen, C., Linse, K., Copley, J. T. and Rogers, A. D. (2015). The 'scaly-foot gastropod': a new genus and species of hydrothermal vent-endemic gastropod (Neomphalina: Peltospiridae) from the Indian Ocean. Journal of Molluscan Studies. 81(3): 1-13. doi:10.1093/mollus/eyv013

Nakamura, K, Watanabe, H, Miyazaki, J, Takai, K, Kawagucci, S, et al. (2012). Discovery of New Hydrothermal Activity and Chemosynthetic Fauna on the Central Indian Ridge at 18u-20uS. PLoS ONE 7(3): e32965. doi:10.1371/journal.pone.0032965

Oliver, P. G. & Holmes, A. M. (2006). New species of Thyasiridae (Bivalvia) from chemosynthetic communities in the Atlantic Ocean. Journal of Conchology. 39(2): 175-183; figs 1-32.

Suzuki, Y. et al. (2006). Sclerite formation in the hydrothermal-vent 'scaly-foot' gastropod - possible control of iron sulphide biomineralization by the animal. Earth and Planetary Science Letters 242. 39-50.

Yao, H. et al. (2010). Protection mechanisms of the iron-plated armor of a deep-sea hydrothermal vent gastropod. Proceedings of the National Academy of Sciences 107.3 (2010): 987-992. http://dx.doi.org/10.1073/pnas.0912988107

Every week we tweet about molluscs on #MolluscMonday via our @CardiffCurator Twitter account. This is a great opportunity for us to showcase some of the amazing specimens in our collections at the Natural Sciences Department of National Museum Cardiff. We also talk about some of the research work we do and highlight some of the fantastic molluscs that are out there.

So why not find out what we have been tweeting about over the last few months in our latest Storify Story 'Stunning Shells'.

If you find these interesting you can also follow us on Twitter.

And why not follow our Natural History conservators as well @NatHistConserve

Following on from our last beekeeper's report, Ben tells us what has been happening:

11th June: “Returning from my travels it was exciting to go see the bees again. I must admit I was anxious, mainly because earlier in the week there had been reports on Wales Online of a swarm in the City Centre. The reported swarm had caused mayhem in the brewery quarter when a few thousand bees descended on a table outside the Yard public house.  When I’d heard about this swarm I feared the worst, were they our bees? Had we missed something? I’d heard reports from some of the museum technicians that there had been clouds of bees up near our hives on that Monday – perhaps that was them swarming!

I can’t describe my relief when I opened the hive of our strong colony to discover that it was full of bees. They were there, all present and correct! The weather was perfect, warm and still, ideal for thoroughly going through the hive! So, removing the heavy super full of honey, I delved straight into the brood box with the help of Sally and lots of smoke! I must admit though, hearing of Nigel’s six stings didn’t fill me with confidence! There are a lot of bees in this hive now and actually seeing what’s happening on the frame is really quite difficult! Going through each frame carefully revealed two Supersedence type queen cups and several play cells (unlaid cells where the bees practice making queen cells). These were removed and the hive was carefully put back together and some of the bees coaxed back inside! Interestingly, now the hive is very full, bees seem to accumulate at the entrance and around the lip of the brood box and they often need a bit of smoke to encourage them back inside.

On opening the weaker hive I was delighted to see that the bees have substantially increased in number and activity. The colony has increased in strength from the 1.5 frames of bees to 5 full frames of bees. Without wanting to disrupt the bees too much, I quickly went through the hive to check the brood pattern and food supplies. Seeing that there were adequate capped reserves of honey and that lots of the bees were returning covered in pollen I closed the hive up and strapped it back down.  Just as we were finishing up Sally was stung! I think the first time for the female bee keepers! Rather painfully she’d been stung right on her heal, somewhere I’d been stung previously so I can vouch for the fact that it really does hurt!

Perhaps our bees aren’t so choosy about who they sting after all!”

Every week on #FossilFriday we like to highlight specimens from the palaeontological collections of the Natural Sciences Department at Amgueddfa Cymru - National Museum Wales, via our @CardiffCurator Twitter account. Sometimes they are fossils on display at National Museum Cardiff, whilst at other times they form part of the collections behind the scenes.

Interested in trilobites, ammonites and dinosaurs? Then why not find out what we have been tweeting over the last year or so in the following two Storify Stories: ‘Friday is Fossil Time’ and ‘Fantastic Fossils’.

If you find these interesting why not follow us on Twitter.

On the 5th June undeterred by his previous stinging incident Nigel ventured up to the rooftop hives, this time accompanied by Sally.  The weather was much better for this visit, a nice sunny warm day with temperatures about 17 °C and very light winds.  The pair started checking the hives, the weaker colony was its usual slightly depressed self, it was noted that there were reserves of honey and a reasonable number of capped brood on the central frames of the hive. The beekeepers went through the frames one at a time and inspected the bees and despite there being far fewer bees in this hive the queen couldn’t be spotted! She’s unmarked and really quite a small queen bee compared to our other one, so it’s not unsurprising that she’s hard to spot even if there are only a few bees!

The strong colony was thriving and incredibly busy as usual. The small frames in the super are getting heavy with honey and some of the frames are almost full and the bees are sealing them with a cap of wax. Looking through the large Deep National brood box frames it was clear that there were more queen cells being produced. Sally and Nigel removed 11 cells – some which were definitely queen cells and some others were suspect drone or play cells (cells where the bees test building queen cups but never lay any eggs), clearly our bees are intent on producing a new queen but why? Queen cups/cells can be several different types: Emergency Queen Cells- produced when the queen is dead or lost; Swarm Cells, produced around the bottom of the frames and are completely vertical and lastly and the type we seem to have most of, are Supersedence Cells. These long vertical cells are produced mid frame on the face of the comb. The intention of these cells is to produce a replacement queen, usually when the existing queen is old or is running out of sperm. Really there should be no need to remove these Supersedence cells but with a young queen, bred last year, and lots of healthy brood being produced, removal of these cells seems like a wise precaution. In the next few weeks we’ll be bringing our bee keeping mentors from Natures Little Helpers to advise on how best to deal with them in the long term. 

There was more pain for Nigel this inspection, although he was wearing a smock and veil over the top half of his body he only had thin suit flannel trousers on!

Over many of the past inspections it has seemed like the bees are preferentially attracted to or angered by male beekeepers. The guys have been stung with far greater frequency than our female beekeepers. This time Nigel must have really aggravated them – he was stung 6 times through his thin trousers! Six times! That must have really hurt- I bet there was some choice language used!