Tag Archives: Mollusca

Guest researchers: Carlo

Untangling the diversity and evolution of Sea Hares

Aplysia parvula; Føllingen, Norway; Photo by Nils Aukan

Aplysia parvula; Føllingen, Norway; Photo by Nils Aukan

Sampling and freezing at Askøy

Sampling and freezing at Askøy

Dr Carlo M. Cunha from the Metropolitan University of Santos in Brazil (Universidade Metropolitana de Santos), a world expert in the diversity and systematics of Anaspidea heterobranch gastropods, visited the Natural History Museum of Bergen for a month during January/February 2017 to study our scientific collection of these molluscs. The visit was funded by the University of Bergen´s Strategic Programme for International Research and Education (SPIRE).

The Museum holds a large amount of material from the Scandinavian region, but also from the Mediterranean, Macaronesia islands, Caribbean, and western Indian Ocean.

These marine molluscs commonly known by sea hares comprise around 90 currently known species and have long been of major interest to biologists because of their large and easily accessible nervous system, which form the basis of numerous neurophysiological works.

Preserved specimen of Aplysia punctata from norway

Preserved specimen of Aplysia punctata from Norway

Dissected specimen of Aplysia punctata from Norway

Dissected specimen of Aplysia punctata from Norway

However, the taxonomy of these molluscs and their evolution are still poorly understood. Dr Cunha is using a combination of molecular and morphological tools to learn more about the worldwide diversity of anaspideans and their phylogenetic relationships.

Dr Cunha visit to Bergen has already resulted in the revision and update of the taxonomy of our Anaspidea collection. The Norwegian species of anaspids were revised and redescribed in detail using electron microscopy and DNA barcoding performed in collaboration with Louise Lindblom (University Museum / Biodiversity Labs).

SEM-image of jaws of Phyllaplysia sp from Florida, USA

SEM-image of jaws of Phyllaplysia sp from Florida, USA

Additionally several other species from around the world were studied and will be integrated in ongoing taxonomic revisions. Keep tuned!

-Manuel

We’ve also had Lloyd visiting recently, you’ll find a post about that on the Marine Invertebrates of Western Africa blog: click here

Door #16: Chaetoderma nitidulum- a spiny, shiny mollusc

Molluscs come in a variety of shapes and sizes, but some of the least known are perhaps the Aplacophora, or shell-less molluscs. Instead of a shell, these worm-shaped molluscs have a cuticle covered in calcareous spicules, or sclerites, that give them a beautiful, glistening appearance!

The very first species of aplacophoran mollusc, Chaetoderma nitidulum, was collected from the Swedish west coast and described by the Swedish taxonomist Sven Lovén in 1844. At the time, it was not even known what animal group the new, strange animal belonged to. It had spicules– could it be related to the spiny sea urchins? It had a worm-like body– could it be related to other worm-shaped animals? It would be almost 50 years before it was conclusively recognized as part of Mollusca. Since then, many more species have been discovered, and today close to 500 species of aplacophoran molluscs have been described.

A specimen of Chaetoderma nitidulum from the Norwegian West Coast Photo: N. Mikkelsen

A specimen of Chaetoderma nitidulum from the Norwegian West Coast Photo: N. Mikkelsen

Chaetoderma nitidulum is known today as one of the common aplacophoran molluscs in the East Atlantic, with a distribution from the Svalbard archipelago in the north, to the British Isles in the south. However, taxonomist have been debating the identity of Chaetoderma nitidulum since shortly after it was described. Some researchers have suggested that it could in fact consist of up to six different species. Other researchers have synonymized it with other species, or suggested that it is not a separate species, but only part of a larger species which has a distribution that spans the entire North Atlantic.

The shape, size and the patterns on the calcareous sclerites covering the body of the aplacophoran molluscs is unique to each species, making it one of the most important characters we have to distinguish between different species.

Calcareous clerites from Chaetoderma nitidulum. Photo: N. Mikkelsen

Calcareous clerites from Chaetoderma nitidulum. Photo: N. Mikkelsen

Looking at the sclerites through the microscope equipped with a cross-polarizing filter gives us a shiny, colorful view of the sclerites. The light shines with different colors depending on the thickness of the sclerites, helping us get a good view of the structure of the sclerites.

Sclerites from Chaetoderma nitidulum viewed under cross-polarized light. Photo: N. Mikkelsen

Sclerites from Chaetoderma nitidulum viewed under cross-polarized light. Photo: N. Mikkelsen

We have recently investigated specimens of Chaetoderma nitidulum from different localities from the entire distribution range of the species. Our investigations have revealed a lot of variation between the specimens, both in the calcareous sclerites and in DNA sequences, separating the specimens into at least two different groups. Could it be that Chaetoderma nitidulum actually represents more than one species?

-Nina

Door #9: Research stay of Juan Moles

Juan working at the Museum

Juan working at the Museum

During my stay at the University Museum of Bergen I have been working on the diversity and systematics of Antarctic philine snails. Most of the samples were collected during different cruises on board of the RV Polarstern in the Eastern Weddell Sea, Bouvet Island, and South Shetland Islands (West Antarctica). I photographed all specimens and then clipped them for the DNA analysis (see pictures).

 

 

 

 

 

I was able to work at the DNA lab with excellent resources for DNA extraction, amplification, purification, and sequencing.

I am indebted to Louise Lindblom who helped me at the beginning of my crusade there. After a first barcoding of all the material we identified six clades, from which we selected a maximum of three specimens to further sequence the ribosomal genes 16S and 28S and the nuclear gene codifying for the Histone 3.

The first phylogenetic tree with all partitions resulted in the finding of novel clades that now deserve further investigation.

Prof. Manuel António E. Malaquias and his PhD Student Trond Oskars helped me dissecting the material for anatomical analyses. Important taxonomical characters were those related to the male reproductive system, the digestive tract as well, and the shell. After the dissections and drawings of the main parts I prepared the hard structures such as the radula, the shell, and the gizzard plates for Scanning Electron Microscopy (SEM) as well as some soft structures after critical point drying. I could photograph all these material at the same facilities of the museum being helped by Irene and Katrine. After the two months of work, I ended up having huge amount of anatomical and molecular data that deserves further processing. See a picture of the radula and a gizzard plate:

Moreover, I was able to join the student diving club and make several dives to get to know the local flora and fauna. I could even collect some other heterobranch slugs for the barcoding project of the museum. See a couple of pictures of the nudibranch Limacia clavigera and Onchidoris muricata.

Overall, Bergen is a nice city to visit surrounded by nice mountains, good (but not cheap) beers, beautiful fjords, and nice people. I hope I can come back with a postdoctoral position to further enjoy the country and meet more Viking descendants.

-Juan

Travelogue from Jenni’s field-trip to California Academy of Sciences, San Francisco

Sea slugs and San Francisco

Phanerophthalmus sp. from Mozambique. Photo: Manuel A. E. Malaquias

Phanerophthalmus sp. from Mozambique. Photo: Manuel A. E. Malaquias

I am three months into the second year of my masters in marine biology, and was lucky enough to start off this semester with a three week trip to San Francisco in order to collect material for my project.

I am writing my master thesis for the University museum of Bergen on the phylogenetic systematics and evolution of a small marine gastropod.

The title of my project is “Patterns of speciation in the Indo-West Pacific, with a systematic review of the genus Phanerophthalmus (Cephalaspidea, Haminoeidae).

I will be using an integrative taxonomic approach combining fine-scale anatomical dissections and molecular phylogenetics to revise the taxonomy and be able to better understand the relationships of the species. The group is restricted to the shallow waters of the Indo-West Pacific and may therefore be used as a good model to study speciation and the historical biogeography of other organisms in this region.

In order to obtain specimens for this project loans have been made from various museums and academic institutions around the world. In total I have 60 specimens on loan from these various institutions, however they still only represent part of the diversity of the genus with limited geographical coverage. The California Academy of Sciences (CAS) in San Francisco holds the largest collection of sea slugs in the World, including specimens of the genus Phanerophthalmus, with over 100 specimens. So, it was arranged for me to visit this large collection and assess what was important for my project. Travelling to CAS also meant I was able to work alongside Dr. Terry Gosliner, a leading expert in the field of malacology.

Phanerophthalmus crawling on seagrass

Phanerophthalmus crawling on seagrass

Pier 39 and California sea lions

Pier 39 and California sea lions

So, on January 16th I got on a 10 hour flight to San Francisco. I stayed at a guest house in the Richmond district of San Francisco, about 40 min walk or 30 min bus from CAS.

Waking up on Sunday morning I was a bit jetlagged, but super excited to be in San Francisco. As it was Martin Luther King Jr. day tomorrow (Monday), I had two days to recover from the flight and adjust to the time difference (9 hours behind Bergen!).

I decided to go and explore the city so I took a bus to downtown San Francisco and went to Fisherman’s Wharf, to Pier 39 where the Aquarium of the bay is and also the California sea lions.

On Monday I went to see where I was going to be spending the next three weeks: at the California Academy of Sciences. Situated in Golden Gate park, the surroundings were beautiful.

Golden Gate park

Golden Gate park

Golden Gate Bridge

Golden Gate Bridge

 

After visiting the grounds of CAS I wandered over to the Golden Gate Bridge. There was rain in the air and the fog was coming down but the view of the bridge was spectacular.

 

 

 

 

 

 

California Academy of Sciences

California Academy of Sciences

Tuesday morning I arrived at CAS eager to dive into the collections. Terry met me at the staff entrance and after a chat and a coffee we got to work. The CAS database contained more than 100 specimens of Phanerophthalmus. The first few days were spent examining labels and matching live photos with specimens. The amount of material was a bit overwhelming and even though I would have liked to look at it all, this would not be possible during my short three week visit. So with guidance from my supervisor, Manuel Malaquias, I was able to focus on the most important specimens. As I am looking at the phylogeny of Phanerophthalmus it is important for me to have specimens which I can extract DNA from. It is also useful to know what these animals looked like live in order to maybe use the external morphology as a character for determining species.

The three weeks flew by so quickly. I spent my days with the collections, dissecting specimens and also got the opportunity to try the academy’s brand new scanning electron microscope. Terry was an amazing host and kept me busy. A huge thank you to him for dedicating so much time towards helping me out. Also, a huge thank you to everyone else at the academy for being so nice and welcoming. After my three weeks at CAS I had a few days to be a tourist in the city. My last weekend in the city happened to be Super Bowl 50 weekend and the city was buzzing with people and events. All in all I had a great visit, and now I have lots of material to carry on working with back in Bergen.

The collections (top), my dissection station (bottom left) and the male reproductive of Phanerophthalmus

The collections (top), my dissection station (bottom left) and the male reproductive of Phanerophthalmus

Scanning electron microscope session with Terry

Scanning electron microscope session with Terry

Alcatraz

Alcatraz

The amazing redwood trees at Muir Woods just outside the city

The amazing redwood trees at Muir Woods just outside the city

Keep calm and focus on sea slugs

Keep calm and focus on sea slugs

-Jenni

Berthella sideralis, a rarity finally documented alive and barcoded!

The Pleurobranchidae sea slug species Berthella sideralis was described by the Swedish malacologist Sven Ludvig Lovén in 1846 based on specimens collect at Bohuslän, in southern Sweden not far from the city of Gothenburg. This species has hardly been mentioned in the literature after its original description, and no images of life species are to our best knowledge available in books, research papers or even web platforms – until now!

A synthesis of the morphological features of B. sideralis can be found in Cervera et al. (2010) who studied in detail two specimens collected during 1930’s in Trondheimfjord as part of a phylogenetic study of the genus Berthella.

Recently, in late November 2015 during a Museum scientific cruise – there is a blog post about this day of field work here – we collected one specimen in Hjeltefjorden (around Bergen) at 220 meters depth using an RP-sledge. This specimen is here documented and was recently genetically barcoded as part of our effort to barcode the Norwegian marine fauna through the NorBOL project.

A live specimen of Berthella sideralis. Ths scale bar i 5 mm. Photo: K. Kongshavn

A live specimen of Berthella sideralis. The scale bar i 5 mm. Photo: K. Kongshavn

Berthella sideralis is only known from Sweden and Norway. In Norway it has been reported between Bergen and Finnmark.

Reference: Cervera, J L., Gosliner, T. M., García-Gómez, J. C., & Ortea, J. A. 2010. A new species of Berthella Blainville, 1824 (Opisthobranchia, Notaspidea) from the Canary Island (Eastern Atlantic Ocean), with a re-examination of the phylogenetic relationships of the Notaspidea. Journal of Molluscan Studies, 66: 301–311.

-Manuel & Katrine

Door #21: A Norwegian oddity

In 1939 the Swedish malacologist Nils Odhner described the nudibranch Berghia norvegica based on two specimens collected at Frøya and Stjørna in the mouth of the Trondheimsfjord.

After its original description this species has been found very few times, the first of them by Hennig Lemche a Danish malacologist who in 1958 collected a single specimen, today housed at the Natural History Museum of Bergen (ZMBN 62033). The importance of this specimen, until recently the only one apparently available in museum collections, was demonstrated by its use in a systematics review of the genus Berghia recently completed by a team of Spanish and American researchers.

The original description of Berghia norvegica is fairly detailed, but was based on preserved specimens and therefore the colouration of this species remained elusive until very recently. For over half a century nothing was known about the colouration of this beautiful and unique animal and is only in 2011 and subsequent years that Berghia norvegica is finally rediscovered by divers and researchers participating in the NudiSafaris organized at Gulen in Sogn og Fjordane just north of Bergen.

These recent discoveries revealed the extreme beauty of this delicate animal and generated the first live images of this endemic and emblematic species of the Norwegian fauna, which we here illustrate with a photograph taken at Gulen on March, the 15th of 2014 at 38 m deep and kindly made available by Kåre Telnes author of the website “The Marine Fauna and Flora of Norway”.

The sea slug Berghia norvegica, an endemic species from Norway. Photo: Kåre Telnes.

The sea slug Berghia norvegica, an endemic species from Norway. Photo: Kåre Telnes.

Suggested reading:

Carmona, L., Pola, M., Gosliner, T. M. & Cervera, J. L. 2014. The Atlantic-Mediterranean genus Berghia Trinchese, 1877 (Nudibranchia: Aeolidiidae): taxonomic review and phylogenetic analysis. Journal of Molluscan Studies, 80: 482–498.

Evertsen, J. & Bakken, T. 2013. Diversity of Norwegian sea slugs (Nudibranchia): new species to Norwegian coastal waters and new data on distribution of rare species. Fauna Norvegica, 32: 45–52.

Odhner, N.H. 1939. Opisthobranchiate Mollusca from the western and northern coasts of Norway. Det Kongelige Norske Videnskabernes Selskabs Skrifter, 1: 1–93.

Door #18: A photosynthetic animal

You may already be confused with the title, but you did read it well! Animals can do photosynthesis and most incredibly some species are more efficient than plants or algae. Yet, this achievement is not for all; you must be special, you must be unique…, you must be a sapsucking slug!

Ercolania sp. feeding inside algae (Photo: M. Malaquias)

Ercolania sp. feeding inside algae (Photo: M. Malaquias)

This is a process named kleptoplasty (= chloroplast symbiosis; see Door #2 of this calendar series) where the slug while feeding from the plant tissue does not digest the chloroplasts but instead migrate these organelles to specific parts of the body where they remain active producing sugars that become available to the slug.

There are two species of sapsucking slugs with a remarkable life-history. The spectacular and rare tropical species Ercolania endophytophaga and E. kencolesi both only known from Australia do not retain chloroplasts as other species do, but they do feed on algae, however, only on a very special kind – the green grape-algae of the Order Siphonocladales. These are syncytial algae made of massive single cell grape-shaped structures which the animal pierce to move in and leave inside until “green-matter” is available.

detail of Ercolania sp. inside algae (Photo: M. Malaquias)

detail of Ercolania sp. inside algae (Photo: M. Malaquias)

I was very fortunate to find one of this slugs back in January 2014 in southern Mozambique. Usually one has to collect a large quantity of algae to carefully search through later on in the lab and hope for the best! However, in that afternoon while sampling in a beautiful shallow tidal tropical reef in Paindane sluggishly looking at a facies of a “grape-alga” growing over a boulder I suddenly notice a tiny animal moving gently inside the algae. I grabbed a few bunches of algae into my sampling jar to look at later on…, and voilà… I was rewarded with a few specimens of one of this spectacular and difficult slugs most probably an undescribed species, the first from the Indian Ocean.

Ercolania sp. after removal from algae (Photo: M. Malaquias)

Ercolania sp. after removal from algae (Photo: M. Malaquias)

-Manuel

Door #15: Guest researchers: Ivan

Ivan Nekhaev from Murmansk came to the University museum in November for a two week stay where he examined some of our mollusc collection. He kindly agreed to participate in our Advent blog adventure, and here is what he had to say:

The main goal of my work at the University Museum of Bergen was studying of minute snails of the family Rissoidae (and drinking a couple gallons of coffee as well :-)).

Rissoids, like many gastropod groups, are more diverse in tropical and subtropical waters whereas the number of species reached northern areas in their distribution is remarkably low: within the several hundreds of northern Atlantic rissoid species, slightly more than dozen of species are know from the adjacent part of the Arctic Ocean. Nonetheless, anatomy for the majority of species had never been investigated and hence the taxonomical status and generic position of some Arctic representatives of the family is questionable, while the accurate data on species composition are still absent for many regions of the Eurasian Arctic.

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During my work with the collections of the University Museum I investigated morphology of ten Scandinavian and Arctic species. These data will be used in revision of Eurasian Arctic rissoids and provide me with a good material for the further investigations in “southern” rissoidean snails.

-Ivan

Door #14: A world of colour and slime

Welcome to the world of Nudibranchs!

Flabellina rubrolineata (Mozambique) Photo: M. Malaquias

Flabellina rubrolineata (Mozambique) Photo: M. Malaquias

The nudibranchs are among the most beautiful animals in our seas. The palette of colours, shapes, and adaptations depicted by this group of gastropod molluscs has no parallel. Some species have no more than few millimetres where others can reach nearly half a meter. Some have a smooth skin, others are covered with long and delicate appendices.

Chromodoris boucheti (Mozambique) Photo: M. Malaquias

Chromodoris boucheti (Mozambique) Photo: M. Malaquias

Phillidia ocellata (Mozambique) Photo: M. Malaquias

Phillidia ocellata (Mozambique) Photo: M. Malaquias

Most are benthic, but some are pelagic drifting with the oceanic currents. Nudibranchs feed on sponges, bryozoans, crustaceans, and cnidarians and even can incorporate in their tissues nematocysts sequestered from their prey which they use in self-defence. Probably, the most striking feature of these gastropods is the lack of a shell and presence of bright colours. These colours are usually a warning signal indicating the presence of deterrent chemicals some of them with pH values as low as 1 or 2. Some of these chemicals are biologically active and have been investigated for the treatment of several types of cancer diseases.

Flabellina pedata (Norway) Photo: M. Malaquias

Flabellina pedata (Norway) Photo: M. Malaquias

Polycera quadrilineata (Norway) Photo: M. Malaquias

Polycera quadrilineata (Norway) Photo: M. Malaquias

-Manuel

Door #11: Just a white blob?

Colobocephalus costellatus repainted from M. Sars (T.R. Oskars)

Colobocephalus costellatus repainted from M. Sars (T.R. Oskars)

When researching small, obscure sea slugs you are bound to run into surprises. Partly because it often takes a long time between discovery and identification, and also because a lot of the really interesting stuff is first revealed when new methods become widely available.

In 2011 a team of researchers from the Invertebrates collection were sampling specimens in Aurlandsfjorden for the Invertebrate collections and range data for the Norwegian Biodiversity Information Centre (Artsdatabanken). Among other interesting critters they found a 2 mm long white blob. While not initially impressive this small blob turned out to be the enigmatic cephalaspidean sea slug Colobocephalus costellatus (Cephalaspidea: Heterobranchia) described by Michael Sars from Drøbak in 1870. At the time of its re-discovery it was thought that this species, which is unique for Norway, had not been seen or collected since M. Sars first laid hands on it 145 years ago (more (in Norwegian) here). However, you continuously discover more information in the course of scientific work. During their work on the enigmatic slug Lena Ohnheiser and Manuel Malaquias found in the literature that the species had in fact been discovered a couple of times since 1870, first by Georg Ossian Sars in Haugesund some years after his father, and more recently by Tore Høisæter of Bio UIB in Korsfjorden outside Bergen.

Still, no in-depth analyses have been done on this species since M. Sars until Nils Hjalmar Odhner of the Swedish Natural History Museum drew the animal from the side showing some of the organs of the mantle cavity.

Most authors have had real difficulties to place this slug within the cephalaspids, and M. Sars even thought is possible that the slug might not be an opisthobranch. Some placed it within Diaphanidae based only on the globular shell, a family that has been poorly defined and often used as a “dump taxon” for species that hare hard to place. Yet others thought it might even be the same as the equally enigmatic Colpodaspis pusilla, which has been suggested to be a philinid sea slug (flat slugs digging around in mud and sand).

What was unique about the most recent find was that this was the first time it was collected alive and photographed with high magnification. The material was also so fresh that Lena and Manuel could dissect the animal and study its internal organs. In their 2014 paper “The family Diaphanidae (Gastropoda: Heterobranchia: Cephalaspidea) in Europe, with a redescription of the enigmatic species Colobocephalus costellatus M. Sars, 1870” they tried to resolve the relationships between these globe shelled slugs. What they found was that Diaphanidae was likely not a real grouping of species, containing at least three distinct groups, where one group was Colobocephalus and Colpodaspis, which were closely related to each other, but also quite distinct.

Colobocephalus costellatus M. Sars, 1870. Photo Lena Ohnheiser, CC-BY-SA. Also featured on http://www.artsdatabanken.no/File/1292

Colobocephalus costellatus M. Sars, 1870. Photo: Lena Ohnheiser, CC-BY-SA. Also featured on http://www.artsdatabanken.no/File/1292

Another new development with the sampling in Aurlandsfjorden was that the slugs were preserved in alcohol rather than formalin. Formalin is good for preserving the morphology of animals, but it destroys DNA. On the other hand, alcohol is perfect for preserving DNA. This lead to C. costellatus to be included in a 2015 DNA based phylogenetic analysis of cephalaspidean sea slugs.

Modified Tree from Oskars et al. (2015)

Modified Tree from Oskars et al. (2015)

This resulted in that the slug was found to be indeed an Opisthobranchia, and as Lena and Manuel thought, Colobocephalus and Colpodaspis were placed in their own family, Colpodaspididae. Whereas the traditional “Diaphanidae” was split apart. Even weirder was the sea slugs that were shown to be the closest relatives of Colpodaspididae, which were neither the philinids or the diaphanids. The closest relatives turned out to be slugs that are equally as weird and unique as Colpodaspididae, namely the swimming and brightly colored Gastropteridae (sometimes called Flapping dingbats) and the Philinoglossidae, which are tiny wormlike slugs that live in between sand grains.

*Cousin Meeting*  - "You sure we are related?"  - "Well, the scientists seem to think so. I see no reason to waste a good party!"

*Cousin Meeting*
– “You sure we are related?”
– “Well, the scientists seem to think so. I see no reason to waste a good party!”

So it took 145 years from its discovery before Colobocephalus became properly studied and its family ties revealed, but it is still mysterious as we do not know much about their ecology or diet.

Suggested reading:

Colobocephalus costellatus: http://www.biodiversity.no/Pages/149747

Colpodaspis pusilla: http://www.biodiversity.no/Pages/149766

Philinoglossa helgolandica: http://www.biodiversity.no/Pages/149915

Høisæter, T. (2009). Distribution of marine, benthic, shell bearing gastropods along the Norwegian coast. Fauna norvegica, 28.

Gosliner, T. M. (1989). Revision of the Gastropteridae (Opisthobranchia: Cephalaspidea) with descriptions of a new genus and six new species. The Veliger, 32(4), 333-381.

Odhner, N.H. (1939) Opisthobranchiate Mollusca from the western and northern coasts of Norway. Kongelige Norske Videnskabers Selskabs Skrifter, 1939, 1–92.

Ohnheiser, L. T., & Malaquias, M. A. E. (2014). The family Diaphanidae (Gastropoda: Heterobranchia: Cephalaspidea) in Europe, with a redescription of the enigmatic species Colobocephalus costellatus M. Sars, 1870. Zootaxa, 3774(6), 501-522.

Oskars, T. R., Bouchet, P., & Malaquias, M. A. E. (2015). A new phylogeny of the Cephalaspidea (Gastropoda: Heterobranchia) based on expanded taxon sampling and gene markers. Molecular phylogenetics and evolution, 89, 130-150.

Sars, M. (1870) Bidrag til Kundskab om Christianiafjordens fauna. II. Nyt Magazin for Naturvidenkaberne, 172–225.

-Trond