Amgueddfa Blog: Natural History

Lewis Weston Dillwyn (1778-1855)

Lewis Weston Dillwyn is part of the influential Dillwyn family in south Wales during the 19th century. They were pioneers in photography, culture, industry, politics and science. Lewis Weston himself was a campaigner for social justice, a Whig MP for Glamorgan (1832-37), mayor of Swansea (1839) and a magistrate. He studied the natural world and advanced our scientific understanding of it, becoming a Fellow of the Royal Society and a founder member of the Royal Institution of South Wales.

Lewis Weston was born 1778 to William Dillwyn, an American Quaker and anti-slave campaigner. After settling in England in 1777, William was one of the 12 founding committee members for the Society for Effecting the Abolition of the Slave Trade formed in 1787. In 1802, William established Lewis Weston Dillwyn, then aged 25, as owner of Cambrian Pottery in Swansea. A year later Lewis Weston moved to south Wales and four years after that married Mary Adams, heiress of John Llewellyn, firmly establishing the Dillwyn-Llewellyn family’s influential position in south Wales. He was an abolitionist like his father but was also close friends with the De la Beche family who owned slave plantations up until the early 1830s. His son Lewis Llewellyn Dillwyn married Elizabeth De la Beche in 1838.

It was mainly during the time he was head of Cambrian Pottery that Lewis Weston studied algae.

The Book of Algae

Lewis Weston had a scientific interest in the natural world, most notably plants, beetles and molluscs. At a time when art, industry and science were often pursued in conjunction with one another rather than separately, he introduced many natural history designs onto the products made at his Cambrian Pottery.

The Museum holds Lewis Weston Dillwyn’s book of pressed seaweeds and algae. Inside are over 280 specimens of algae from both fresh and seawater, mainly from Wales and England. Many are thought to have been collected by Dillwyn himself, and many were sent to him by scientists from the UK and Ireland. The book contains algae that were completely new to science and described by Dillwyn for the first time. Some of these new to science algae were discovered for the very first time in Wales. The book is an early record of the natural heritage of Wales and a glimpse into the scientific life of a prominent 19th century philanthropist.

New to Science

It was particularly between 1800 and 1810 that Lewis Weston Dillwyn focussed on algae. He noted that Linnaeus, who was classifying the whole of the natural world, “was too busily engaged in the immense field he had entered on, to spare the time necessary for an investigation of the submerged Algae.” (Dillwyn, 1809, British Confervae). Dillwyn felt he had found a niche for his scientific study.

The algae that Lewis Weston studied was a group with very thin fine branching known as the Confervae. He collected specimens, pressed them and placed them into the book now held at the Museum. His many connections led to a network of scientists who would send him specimens he was interested in to his home in south Wales. He described 80 kinds of algae new to science.

Someone in Dillwyn’s position could afford to buy a microscope powerful enough to study this group which have very small features. He would also have needed expensive books and his standing in society meant he was able to access the libraries of friends such as William Jackson Hooker and of the Linnaean Society in London, where he was made a Fellow. It also meant he was able to discuss current thinking with other prominent scientists of the time and gauge where to place his efforts.

At the time, there had been little work done on this difficult to study group. Dillwyn knew the algae he was looking at were probably unrelated, but in his published work he put them into one group. He had done the initial pioneering groundwork to describe them but he himself modestly admitted that it was flawed. The pressed algae in his book at the Museum includes what scientists now know belong in many different groups: green algae, red algae, brown algae, lichens, fungi, cyanobacteria, stoneworts and diatoms. Dillwyn published the results of his studies in instalments, culminating in the publication ‘British Confervae’ in 1809.


Further reading

The Diaries of Lewis Weston Dillwyn, transcribed by Richard Morris:

The Dillwyn Dynasty by David Painting (2002):

British Confervae by Lewis Weston Dillwyn:

A Day in the Life of a Natural History Curator

My name is Jennifer Gallichan and I am one of the natural history curators at National Museum Cardiff. I care for the Mollusc (i.e. snails, slugs, mussels, and octopus) and Vertebrate (things with backbones) collections. Just like everybody else, museum curators are adapting to working from home. But what did we use to do on a 'normal' day, before the days of lockdown?

Caring for the National Collections

Most of our specimens are not on display. Amgueddfa Cymru holds 3.5 million natural history specimens and the majority are held behind the scenes in stores. Caring for the collections is an important part of our role as curators. We have to meticulously catalogue the specimens to ensure that all of the specimens are accounted for. As you can imagine, finding one object amongst 3.5 million could take a while.

Harriet Wood (Curator: Mollusca) in the collections

Natural history collections cover a whole range of materials including shells, dried plants, minerals, fossils, stuffed animals, bones, pinned insects and fluid preserved specimens (this includes things in jars).

Cephalopod specimens from the William Evans Hoyle collection

These collections are vital for research, education, exhibitions and display. Some have been in the museum for well over a century, and it is our role to ensure they last into the next century and beyond. We work with specially trained Conservators to monitor the collections and highlight anything that might be at risk, needs cleaning or repair.

Cleaning the skeleton of one of Cardiff famous residents, Billy the Seal

Answering your Questions

We spend a lot of time working with you, our fantastic visitors. Much of our time is spent answering the thousands of enquiries we receive every year from families, school children, amateur scientists, academics of all kinds, journalists and many more. We also host open days and national events throughout the year which are another great opportunity to share the collections. Many of us are STEM (Science, Technology Engineering & Mathematics) ambassadors, so an important part of our role inspiring and engaging the next generation of scientists.

Talking about the collections at the Eisteddfod

Working with Volunteers

Our museums are crammed full of fascinating objects and interesting projects to inspire and enjoy. We spend a lot of time with our excellent volunteers, helping them to catalogue and conserve the collections, guiding them through the often intricate and tricky jobs that it has taken us decades to perfect.

Our fantastic volunteers currently working on transcribing letters from the Tomlin archive of correspondence

Working with Other Museums

Museums across the world are connected by a huge network of curators. We oversee loans of specimens to all parts of the globe so that we can share and learn from each other’s collections. We have to be ready to deal with all manner of tricky scenarios such as organising safe transport of a scientifically valuable shell, or packing up and transporting a full sized Bison for exhibition.

A meeting of mollusc curators as part of a research project at the Natural History Museum, London

Working with Visitors

Despite the fact that a large part of the collections are behind the scenes, they are open to visitors. Researchers from across the globe come to access our fantastic collections to help with their studies. We also host tours of the collections on request.

Working with visitors in the collection, examining Sawfish rostra

Making Collections Bigger and Better

Despite having millions of specimens, museum collections are not static and continue to grow every year. Be it an old egg collection found in an attic, or a prize sawfish bill that has been in the family for generations, it’s an important part of a curator’s job to inspect and assess each and every object that we are offered. Is it a scientifically important collection or rare? Has it been collected legally? Do we know where and when it was collected? Is it in a good condition? Do we have the space?

Bryn, our Sumatran Tiger was donated to us in 2017 from Colwyn Bay Mountain Zoo

Creating New Exhibitions

A fun part of the job is working with our brilliant Exhibitions department to develop and install new exhibitions. We want museums to be exciting and inspiring places for everyone so we spend a lot of time making sure that the information and specimens we exhibit are fun, engaging, inspiring and thought provoking.

Adding specimens to a specially created exhibit called Museum in a House, for Made in Roath festival, 2015

Being Scientists

Last but definitely not least, when we aren’t doing all of the above, we are doing actual science. Museums are places of learning for visitors and staff alike. Many of us are experts in our field and undertake internationally-recognised research. This research might find us observing or collecting specimens out in the field, sorting and identifying back in the lab, describing new species or researching the millions of specimens already in the collections.

Kate Mortimer-Jones (Senior Curator: Marine Invertebrates) hard at work identifying marine worms

Museums from Home?

Despite lockdown, we are working hard to keep the collections accessible. We’re answering queries, engaging with people online, writing research papers and chipping away at collection jobs from home. And like all of you, we are very much looking forward to when the museum opens its doors once again.

If you want to find out more about the things we get up to in the museum, why not check us out on Twitter or follow our blog? You can also find out more about all of the members of the Natural Sciences department here.

In my previous blog I explained what rafting bivalve shells are and how Caribbean bivalves are ending up on British and Irish shores attached to plastics. There are numerous records of non-native bivalves on plastics in the southwest of Ireland and England but nothing has yet been reported in Wales, which is something that I’m trying to rectify. To encourage recording I’m enlisting citizen scientists – volunteers from the general public – who can help to spot and identify these rafting species in Wales. But first of all, I want to check to see if there are rafting species turning up on our shores so I began talking to groups who already go out on the shores to survey, beach clean or educate.


PLANED team at Wiseman's Bridge beach

In December 2019 I met with a fantastic group of people at PLANED in Narbeth. PLANED have excellent coastal community links and everyone I spoke to was enthusiastic and willing to incorporate the rafting bivalves project into their usual activities of beach cleans, foraging, outdoor activities or education.  They were keen to help record any rafting species that they discover and we talked about how to identify any bivalves found. Since then I have been working on an identification guide that I plan to develop with the help of these community groups.


Pembrokeshire National Parks staff and volunteers looking for plastics at Freshwater West beach

In February 2020 I met up with 35 people at the Pembrokeshire Coast National Parks offices in Pembroke Dock. They were eager to learn more about non-native bivalves on plastics. After lunch, those daring enough braved the freezing temperatures and gales to carry out a mini beach clean at Freshwater West beach. We found a lot of large plastic items in less than half an hour which we brought back to the car park for a closer look. Even though there were a lot of pelagic goose barnacles (stalked crustaceans related to crabs and lobsters that attach to flotsam) on some items, proving that the items had been floating in the ocean for a long time, no non-native bivalves were found.

Plastics found at Freshwater West beach - no bivalves attached, though!

In early March two colleagues and I attended the annual Porcupine Marine Natural History Society’s

Presenting the rafting project at the annual Porcupine Marine Natural History Society Conference at SAMS (Scottish Association for Marine Science).

conference where I presented the project and had several more offers of eyes on the ground to record and test the identification guide, which is great news.  I’ve also set up a Facebook page where volunteers can post images of any suspected non-native bivalves for me to identify. I’m hoping to meet up with several more groups later in the year to ask them to look for these pesky hitchikers so we can find out if and where they are attempting a Welsh invasion!

If you would like to help record non-native bivalves on plastics on Welsh beaches then do contact me at


For our avid blog readers, you might recall previous articles about a group of worms which certainly dig! They are the shovel head worms, or to give them their scientific name, magelonids. Shovel head worms are a small group of marine bristle worms (polychaetes), which are sea worms related to earthworms and leeches, with bristles along their bodies. Shovel head worms get their name from their spade-shaped heads, which they use to dig in soft sediments such as sands as muds. They are pretty small and delicate, so although we have them around our coasts, they are often tricky to find. Therefore, they are not as well-known as other marine bristleworms such as lugworms and ragworms, often used by fisherman as bait! Their size also means that they can be pretty difficult to collect, ever tried looking for a worm less than 1 mm wide on a beach? We have! Despite their size they are quite beautiful worms (although, I may be slightly biased!) and like other marine bristleworms they are an important food source for many other sea creatures, and also are the gardeners of the ocean, re-working the sediments like earthworms do on land.

Shovel head worm, Magelona filiformis, first described off Plymouth in 1959

Although, I wear many different hats in the museum, one of my principle jobs is being a taxonomist. Taxonomy is the science of naming, describing and classifying life on earth. That may be finding new species, or re-describing species which were discovered many moons ago. When we find a new species, we draw it, take photographs of it (sometimes using Scanning Electron Microscopes enabling us to Zoom in really closely!), describe it and then pick a name for it in Latin. To give you an example here is a species that I described with colleagues in China.

Shovel head worm, Magelona equilamellae, first described off Southern France in 1964

So, what have we been up to recently? We have been reviewing the shovel head worms of Europe, of which there are currently nine species known. Four of which were first described from the UK, three off France, one off Portugal and one off Sweden. Although, these are worms we know, back when the species were first described we didn’t know all of the features/characters that we needed to know in order to correctly identify and seperate them. Unfortunately, this means that the worms get mis-identified, causing problems for people who monitor the health of our seabeds! This is where we step in, re-describing the species and producing identification keys and guides to help people in the future. Over the last year we have been busy reviewing the species, a paper on which has just been published. Now scientists all around the world will be able to correctly identify their European shovel head worms.

Eight species of shovel head worm found in Europe

We have been doing this with a Professional Training Year Student from Cardiff University, and colleagues from Spain and Portugal


Find out more about our work on ‘Worms that Dig!’

West African Worms that Dig 

More on West African shovel head worms

Species new to science, Shovel head Worms from around the world



Chama sarda from the Caribbean, found in western Ireland

In the previous blog (What are Non-native (or alien) Species?) I talked about non-native species and how they are transported around the planet. In this blog I’ll tell you a bit more more about rafting bivalves that can cross the Atlantic on plastics and about some of the UK hotspots for these non-native (alien) hitchikers.


What is rafting?

Rafting has occurred throughout geological time, and it is how many terrestrial (land-dwelling) species colonised islands and other regions across the seas. A good example of this is the lemurs of Madagascar. 60 million years ago there were no lemurs on the island of Madagascar, but their ancestors were on the mainland of the African continent. So how did they actually get to Madagascar? Palaeontologists tell us that rafting is the answer. Back then, Madagascar was closer to the mainland and currents in the Mozambique Channel were much stronger towards the island than they are now. The lemurs’ ancestors must have found their way onto mats of vegetation or branches and by chance rafted to Madagascar. A completely fluke event! 


Violent storms assist the dispersal of non-native species on plastics

Today, our litter ends up in the oceans and provides unnatural vehicles for marine non-native species. Over the last decade more than 20 species of Caribbean bivalve shells have ended up on British and Irish beaches attached to plastic buoys, bait buckets, ropes and others items – even a piece of a car running board! The latter had three different types of Caribbean bivalves attached, one of which, the Bicolor Purse Purse Oyster, is an invasive species in Brazil. Violent storms help to throw the plastic objects high onto our shores and they are then found by beach cleaners, beachcombers and others on the strandline at the top of the beach. Many of the shells or photographs are sent to Amgueddfa Genedlaethol Caerdydd - National Museum Cardiff to be identified and hence to work out where they came from.


Conveyor belts and hotspots

General locations of rafting bivalve records in the southwest of Britain and Ireland

The rafting species that we are studying start off attaching to plastics in the Caribbean. These plastics eventually float into the warm ocean currents of the Gulf Stream, which originates in the Gulf of Mexico, and provides a conveyor belt to transport non-native species across the Atlantic Ocean to the British Isles. Once here, violent storms then deposit the plastics, with their hitchhikers still attached, onto our shores. 

The hotspots for non-native species records are in the southwest of England and western Ireland, but there are also records for western Scotland. Strangely enough there are no records for Wales, even though some of the beaches are prime, exposed shores similar to those in Ireland and England. 

I want to discover if there are any welsh hotspots for rafting bivalves, find out which beaches to search and to encourage people to go out to those locations to try and get some records for Wales. 


Why should we monitor these species?

It is important to establish points of entry for any non-native species, which is why we need to map where the rafting species are arriving so that we can monitor numbers of any species arriving alive that could possibly pose a threat. When a species moves to a new location, the species that already live there have to adapt to cope with the newcomer. This can put a strain on populations that use the same food source or habitat as the invading species, which is why we want to know where these rafting species are washing ashore. All the rafting species that we’ve encountered so far cannot reproduce in our waters as they need warmer sea temperatures of 20°C or more to breed. However, if sea temperatures continue to rise, climate change could aid more rafting species to create self-sustaining populations here which could become a real problem


The Bicolor Purse Oyster – an invasive species in Brazil

Byssus threads of Bicolor Purse Oyster from the Caribbean

Of the non-native rafting species found so far in the UK, the Bicolor Purse Oyster (Isognomon bicolor) is the one that has shown up in the greatest numbers. It was first described as a species in 1846 by C.B. Adams who collected it in Jamaica. It has been spotted around the coasts of Florida, Texas and Bermuda and several of the Caribbean islands all of which are considered its natural range. However, in 1970 it was recorded outside its natural range in the eastern state of Rio Grande do Norte in Brazil. It has since moved further southwards and is considered an invasive species in Brazil as it is competing with native oysters and mussels for space and is spreading quickly. 

The Bicolor Purse Oyster in Britain and Ireland

The Bicolor Purse Oyster has been found in Cornwall, Dorset and western Ireland by eagle-eyed beachcombers. They noted locations, objects that the oysters were attached to, and they collected the shells. The beachcombers are great photographers so we have a record of the variety of sizes, shapes and colours of the shells found here. The Bicolor Purse Oyster is small (up to 28mm), flattened and elongated. The outside is beige and white, sometimes with purple blotches and is smooth apart from being a bit flaky-looking. The front of the shell has byssus threads of pale to dark brown that protrude ready to attach to hard surfaces. In its natural range this species attaches to rocks and is commonly found in the Florida Keys. 


What next?

Although there are lots of records of rafting species in Ireland and England, there are none for Wales. Does that mean that they do not wash ashore in Wales? Doubtful! This is why I’ve set up a project to get people out onto beaches looking for any plastics that could be likely rafts. The project involves citizen scientists – volunteers from the general public – who can help to spot these rafting species in Wales.

To find out more about this part of the project see next week's blog entitled Rafting Bivalves - the Citizen Science project.