Tag Archives: Hydrozoa

NOAH goes North again!

A couple of weeks ago, a team of five jellyfish and polyp enthusiasts travelled to Torsvåg, Vannøya, a beautiful location two hours north of Tromsø by car (more about the fieldwork can be found here). Our goal? Collect, identify and catalogue some little-known hydrozoans for Artsdatabanken project NOAH (Norwegian Arctic Hydrozoa). This is the 3rd dedicated NOAH trip to obtain Arctic samples (or examine collections) in the last 12 months! After a very successful Arctic expedition to the West and North of Svalbard on board Kronprins Haakon in the context of the Barents Sea Ecosystem Survey by IMR, and a 1-week workshop at the Institute of Oceanology Polish Academy of Sciences (IOPAN) co-organized by our colleague Marta Ronowicz, this time we focused on the underexplored coasts of northern Norway.

A collage of reserch related photos; people working in lab, a reserach vessel

Recent NOAH-related sampling trips. On top, Barents Sea Ecosystem Survey by IMR on board icebreaker Kronprins Haakon; in the middle, at IOPAN examining Marta Ronowicz’s extensive collection; bottom, NOAH team in Torsvåg (Troms). Pics: Joan Soto, Piotr Bałazy, Robert Johansen

Cruises, especially on cutting-edge icebreakers crashing ice on their way to the poles, are a lot of fun, but getting deep-water samples of both jellyfish and polyps is all but easy. Consequently, even when we carefully optimize the sampling procedures, some fragile species often arrive damaged or in bad shape. This time, we collected shallow-water specimens using our own hands. In addition to (MANUAL!) net deployments at ca. 180 m depth, we intensively checked marinas, tide pools, and shallow infralittoral environments by snorkeling. It worked fantastically well for those picky jellies and polyps which tentacles/polyps get lost after being trawled or towed with a tone of hard-bodied invertebrates and slimy fish within massive nets. We took the opportunity to document them in detail using both microscopes and macro photography. During our trip, we had the visit of Stine and Linda from Artsdatabanken. They even kindly gave us a hand collecting jellyfish from the piers! Good catch!

A photo collage of scientists at work, and a reindeer (presumably also at work)

Wide array of sampling methods, landscapes and local fauna, including a brand new wet lab (before: living room) specially made for the occasion. Stine and Linda testing our hand nets and successfully collecting some jellies. Pics: Joan Soto, Praveen Raj.

Each of us had our favorite species and top findings for the trip, and we were really excited to see alive and in good shape those species we have only examined within preserved collections, or only read about in scientific publications. These findings will definitely contribute to a better knowledge on the true diversity and distribution of these little known species, some of which have rarely been reported that far north in continental Norway.

I (Joan) stop here and leave you with some insights from the other NOAH team members that joined the trip: Marta and Praveen.

From Marta:
This was such a very interesting experience! During my work I usually study deep ecosystems, so I do not often see fresh samples of benthic hydroids, and when I do, they are often damaged by the sampling gear (e.g. bottom trawl, beam trawl…). This trip to Torsvåg has allowed me to sample the intertidal pools and marinas with my own hands, discover the great diversity that exists just below the surface, and to see multiple species in a way I never seen before.

For me, the most interesting species were undoubtedly the athecate hydroids, such as the incredibly beautiful Zanclea spp. and Sarsia spp. These animals are extremely fragile due to the lack of a theca to protect the polyp. In Torsvåg, I saw athecate hydroids of extraordinary quality, studied their sexual structures, their morphology, colours, behaviour…  Simply: WOW!!! I’m very much looking forward to the next NOAH trip!

Collage of microsope images of hydrids (looks like sticky flowers), happy people in lab and out in the field

During our sampling trip, Marta Gil (visiting researcher) showed a lot of excitement about the diversity in the intertidal pools and collected beautiful athecate polyps, all with reproductive structures! Pics: Joan Soto.

From Praveen:
My first sampling trip after joining the Cnidaria and Ctenophora Team as a PhD student was nothing short of exhilarating. Our team, led by Joan Soto, was focused on various life stages and projects related to the phyla Cnidaria and Ctenophora. Although I had conducted similar sampling procedures in India, working with live specimens of both planktonic and benthic stages of Cnidarians in Torsvåg was a new and fascinating experience.

One of the trip’s most challenging parts was venturing into open waters with a small fishing boat to collect samples. We had to troubleshoot a bit on board, but it finally turned out to be a success. Despite not finding Dimophyes arctica, one of the target species for my PhD, I was captivated by the immense diversity of hydroids in the piers near the island, some of which might be the so-far unknown polyp stage of some known Norwegian hydromedusae. Special thanks to Luis and Marta, who taught me a lot about hydrozoan taxonomy, and Cessa and Jon for driving the boat and patiently wait for the net to be recovered.

The research was undoubtedly the focus, but the social activities and adventures we shared were equally memorable. Torsvåg itself was mesmerizing, with its high mountains and breathtaking views. We all enjoyed evening hikes and took advantage of the midnight sun, which provided a perfect balance to our intense sampling schedule. Our group dinners were another highlight of the trip for me: with colleagues from 7 different nationalities and 3 continents, we had a delightful variety of cuisines as we took turns for preparing dinner.

All in all, this sampling trip was an incredible blend of scientific discovery and personal enrichment. The stunning landscape and the camaraderie of our team made it an unforgettable experience.

A collage of images, three showing happy poeple out in northern Norwegian nature, and five of different jellyfish photographed against a black baground

Praveen Raj on his first sampling trip for his PhD. He not only captured and identified an impressive amount of jellyfish, but also had a great time hiking around Torsvåg and enjoyed the dramatic landscapes that Northern Norway can offer. Pics: Joan Soto, Praveen Raj, Lea Dober.

From Joan, Marta and Praveen.

My internship at the University Museum of Bergen (Alina)

Hi, I am Alina Lösing, a bachelor’s student from Germany with the great opportunity to join the Cnidaria and Ctenophora team from the University Museum of Bergen for a 6 weeks Internship. This experience was not only a chance to further strengthen my passion in marine biology but also very helpful to gain valuable insight into research and museum operations.

During my time at the museum, I had the chance to join various projects of Joan J. Soto-Angel, including POLE2POLE (Horizon 2020, MSCA) on bipolarity, and Artsprosjektet NoAH (Artsdatabanken) on Norwegian Arctic Hydrozoa. I even had the honor to contribute a small part to it! I focused mostly on the polyp of Stegopoma plicatile, a supposedly widely distributed species present also in both Arctic and the Antarctic waters.

On black background branching animals looking a bit like corals

Figure 1: Living specimen of Stegopoma plicatile collected during the OceanX cruise at 240 m depth (Pictures: Joan J. Soto-Angel)

The first step was to take pictures of the different specimens that were sampled and categorized as Stegopoma plicatile. Further I took pictures of many other species of Arctic hydrozoan polyps and hydromedusae. I learned some useful tricks with the camera while photographing the different species of polyps and medusae.

Part of the project is developing a reliable workflow which allows for a morphological distinction between polyps belonging to potentially different species previously defined molecularly from different areas worldwide. Therefore, I spent a lot of time working with the microscope collecting data which can be crucial to refining the morphological differences between different species. I measured length and width of 380 nematocysts!

The author working in the lab; seen using a microscope with camera on top, and holding a DSLR camera

Figure 2: Taking pictures of the samples with the microscope and the camera (Pictures: Joan J. Soto-Angel)

Furthermore, I underwent training in tissue sampling, a crucial step in preparing the samples for DNA sequencing. It’s all about preventing tissue contamination! Moreover, I had the opportunity to visit the DNA Lab, where I received instruction in their specialized techniques for DNA extraction, PCR, and electrophoresis. Many thanks Cessa for your time and dedication!

The highlights of my internship were of course both sampling trips I got to attend on board the Research Vessel Hans Brattstrøm. On the ship I learned a lot about the specific sampling methods for these incredibly delicate invertebrates. Despite experiencing a bit of seasickness the first time, I assisted with net deployment, sorting the animals, and collecting water samples from different depths.

Wrok on board the reserach wesse (person holding a transparent cylinder with water) and a group photo of the participants

Figure 3: Collecting water samples from a CTD; The Team during a successful sampling day (Pictures: Luis Martell, Praveen Raj)

Apart from an amazing Jellyfish Team, Bergen has many more attractions to offer. I highly recommend packing your hiking boots for your next visit, as the surrounding mountains offer breathtaking scenery. And if you share my passion for the ocean, a visit to the Nordnes Sjøbad is a must. Here you can take a refreshing dip in the frosty ocean before warming up in the heated saltwater pool.

Scenic shots of nature in Bergen

Figure 4: Hike to Ulriken and Fløyen with a view of Bergen (Pictures: Alina Lösing)

 I would like to take a moment to acknowledge Joan’s invaluable contribution to my internship at the University Museum of Bergen. Joan’s dedication and extensive knowledge have made my experience truly unforgettable.


Project ParaZoo: there is a critter inside my jellyfish!

ParaZoo (complete name ‘Metazoan parasites of non-crustacean zooplankton’) is one of the most interaction-focused projects currently running at the Invertebrate Collections of our Museum. This project, funded by the Norwegian Biodiversity Information Centre (Artsdatabanken), aims at studying the different animals that live together inside and on the surface of Norwegian jellyfish. This means that for the next two years we will be looking for tapeworms, flukes, roundworms, and amphipods as ParaZoo tries to answer the question of which of these organisms are associated with gelatinous hosts in Norwegian waters.

ParaZoo is focused on animal parasites and symbionts associated with jellyfish. Thse parasites include roundworms like Hysterothylacium aduncum (left, in Euphysa aurata), amphipods like Hyperia medusarum (middle, on Aequorera forskalea), and flukes like the members of family Didymozooidae (right, in Beroe gracilis). IC: Aino Hosia (left), Katrine Kongshavn (middle), Joan J. Soto-Àngel (right).

Besides jellyfish, arrow worms (Chaetognatha) are also members of non-crustacean zooplankton that host different types of parasites, like this H. aduncum roundworm (Nematoda). IC: Joan J. Soto-Àngel, Luis Martell.

Parasitism and symbiosis are extremely common life styles in the animal kingdom. In fact, some researchers believe that there may be more species of parasites than of free-living animals, given that each free-living species hosts many species of parasites (most of them unique) and those parasites also host their own parasitic tenants. Marine zooplankton is no exception to this trend, and many parasites and symbionts are expected to occur in copepods, krill, and gelatinous zooplankton. Jellyfish and arrow worms, for example, may be important hosts for flatworms and other helminths, yet our knowledge of these animals in Norway is very scarce.

ParaZoo’s logo includes two of the target taxa of the project: roundworms (Nematoda) and hyperiids (Amphipoda). The third main parasitic group covered is flatworms (Platyhelminthes), illustrated by the larvae of Derogenes varicus parasitizing Halopsis ocellata shown in the right side of this figure. IC: Joan J. Soto-Àngel, Luis Martell.

Understanding zooplankton parasites is important because many of them are going to be transmitted to fish, where they may cause serious diseases. To get a better overview of which critters live in non-crustacean zooplankton, ParaZoo will sample, record, and DNA-barcode specimens from all over the country. The collected animals will be included in our museum collections after being identified, documented photographically, and fixed in ethanol. We will then generate an open-access database of information including pictures and DNA sequences that will help with the identification of the parasites. Aquaculture facilities, fishermen, and managers of marine areas will benefit from this database to better plan and counter potential negative impacts caused by the parasites.

Flukes, such as Opechona spp, parasitize gelatinous zooplankton (in this case a sea-gooseberry Pleurobrachia pileus) as larvae called metacercariae. IC: Joan J. Soto-Àngel, Luis Martell.

The larvae of tapeworms (Cestoda) sometimes use jellyfish to reach their definitive hosts: fish. IC: Joan J. Soto-Àngel, Luis Martell.

ParaZoo is committed to present the diversity of jellyfish parasites to all those not familiar with them. In order to do that, we will regularly write entries here on the blog, as well as participate in several academic and not-academic meetings. The official info webpage for the project is available here, so don’t forget to check it out!


Hydrozoan team at ForBio 2022 annual Meeting

Do you remember that feeling of dread before you must present in class about a topic you didn’t really study for? Your mind racing, trying to scramble a coherent story to tell the sea of eyes fixed expressionless on you and your powerpoint? We believe we all have at least one memory of this from our days in college.

That was a similar feeling to what we felt on November 28th, 2022, when we had just landed in Trondheim and were on our way to the Norwegian University of Science and Technology (NTNU) for this year’s ForBio Meeting, a 3-day gauntlet where we will present the Master’s projects we’re currently working on. Except this time, we weren’t presenting in a small classroom full of uninterested teenagers thinking about tik tok dances, but in an auditorium full of fellow researchers who work on your same field, and who will probably have extremely difficult questions at the end of your talk. Being the first time we present in an environment like this, one can’t help but imagine all the worst outcomes

And so we’re sitting there, watching the hours and the talks go by, thinking to ourselves “I should/shouldn’t try that for my talk!”. At lunch, all we think about is our talks. When we’re doing some light sightseeing in Trondheim, all we think about is our talks. We’re laying in our beds the night before, and all we think about is our talks. “How will I make my topic sound as professional and knowledgeable as I want to?”, we think to ourselves.

The day arrives, and again the dread starts setting in, right until the moment they call each of our names. At our every turn, we walk down the steps, grab the microphone, and start talking. Except for some reason, this time it feels like we’re in control. The words flow effortlessly; we even crack a joke or two, and the audience laughs. There’s no stumbling around the words like those college days.

Because this time, we’re not the average seat-warming student. This time, we’re the ones that have spent cold and raining hours on a research vessel or diving to get our samples; we’re the ones who have spent hours working together with our supervisors, reading and learning about our topics; we’re the ones who have spent hours looking down a microscope trying to identify our organisms. This time, we’re the ones who know what we’re talking about, and the audience is there to learn from us.

After each of our talks, we give our acknowledgements, and everyone claps. The questions thrown at you are answered effortlessly, and the moment is finished with a thumbs up to our supervisors, returning to our seats smiling.

The most exciting part for us was showing to experts what we do with our favorite invertebrates: Hydrozoans. These organisms are an inconspicuous class in the phylum Cnidaria that most people ignore. Our job was not only to present what we do with them, but to show what they are, what they do, how fascinating they can be and why they are important. And we think that we did a good job.

Now we’re finally free to enjoy the world famous Trondheim bike lift (and the Nidaros Cathedral too), closing the night with burgers, beer and friends.

Everything has been great on this trip and we will always remember the advice from other professionals; how different or similar the work of each one is; and the feeling that you are part of a group of specialists who are excited to share their knowledge with others. But, above all, we have learned why these conferences are important: Knowing what other researchers are doing gives us the chance to collaborate together and help each other, because working as a team is how science moves forward.

The hydrozoa group (and friends) from UiB participating at the ForBio meeting

Pedro, Ana & Håvard

Student visit – Ana González

MSc student Ana González visited the collections last month as part of project NorHydro, where she spent some weeks in the lab working with her samples. Here is an account of her experience:

The challenge of identifying benthic hydrozoans
Hydrozoa is a fascinating but poorly understood group of invertebrates, in part because their identification is not always an easy task. I have been studying benthic hydrozoan communities for over a year now, in particular those living in the shallow waters of Mallorca (Spain), and I have realized that the diversity of forms and structures in the group is higher than I had imagined at the beginning of my studies, and their identification is more difficult than I expected. The assemblages of hydrozoans in the Mediterranean are of course very different from the ones that occur in Norway, but something that both communities have in common is that morphological identification of the animals (i.e. telling which species is present based only on the characteristics we can observe) is challenging, which is why one of the aims of my visit to the University Museum of Bergen last December was to learn a different technique (DNA barcoding) that can help me improve the identification of my samples in cases when the morphology of the specimens is not good enough.

Some of the morphological characters that are used to identify benthic hydrozoans. On the left side a member of Campanulariidae, with a stolonal colony, and on the right side Monotheca obliqua with an erect colony.

DNA barcoding consists in finding a short DNA sequence (the barcode) that is similar for all members of one species but different from all other species. It is a relatively recent tool that –among other things– has helped the scientific community identify specimens that for one reason or the other cannot be identified based on how they look. In some groups, such as many colonial invertebrates, this technique has become a key asset because the colonies are often too young or not reproductive, or the important characters for identifications may be found only in one stage of the life cycle and not in others. For this visit I had the chance to bring all my samples from Mallorca to Bergen and I set to extracting the DNA of selected specimens, amplifying two different barcode genes (COI and 16S), and obtaining clean sequences for them. I discovered that, when it comes to DNA barcoding, every step of the process is important, and being patient and careful is essential.

Me at the DNA lab, running the electrophoresis for my samples.

Getting good results in the DNA lab depends on several factors like not forgetting any step and avoiding contamination as far as possible, but the work does not end there: once you have your sequences they have to be cleaned, quality-checked, and finally compared with others. This means that having a complete and trustworthy database of DNA barcodes is necessary, especially if you want to use the sequence to help you corroborate the identification of a specimen. When done right and with a good database, the DNA barcodes can be useful to detect differences between hydrozoan assemblages growing in different parts of the world or between different substrates and levels of anthropogenic impact, which is what I am doing in my MSc project.

Left: Clytia sp growing on the marine plant Posidonia oceanica. Center: A polyp of Halecium sp, one of the most difficult genera of Hydrozoa to identify based only in morphology, especially when the colony is not reproductive. Right: Eudendrium sp., found in harbours in Mallorca in high abundances.

The analysis of DNA sequences is a powerful tool to compare specimens of distinct populations and in some cases animals that apparently belong to the same species turn out to be completely different (e.g. cryptic species). This is not uncommon for benthic hydrozoans, which have high morphological diversity but also high levels of plasticity, resulting in colonies from different species sometimes being very similar to each other when they grow in similar substrates. As useful as DNA analyses are, however, it is also important to consider their limitations. For example, while the abundance of each species in a given community is important to describe the ecological status of a habitat, estimating abundance is still not always possible from sequence reads in DNA analyses.

Many cryptic species have been discovered in Aglaopheniidae thanks to the combination of DNA barcoding and morphological analysis

The use of DNA barcodes in my work is not limited to my current project, as I hope my identifications and sequences will help a little bit to improve the databases for future studies of hydrozoan communities in the Mediterranean Sea, and maybe even allow other researchers to compare their samples with the species found on other parts of the world. I think that looking closely at each specimen is the best way to truly know variation, so both morphology observations and DNA analyses should be combined to obtain good estimates of the diversity of a taxon in any locality. For example, whenever the DNA analyses reveal differences in two clades that were thought to be the same species, it is time to search for new taxonomic characters that we might have missed before, and for that reason it is also important to have a good knowledge of the morphology of each species. Both morphological and DNA-based identifications have limitations and advantages so, if you have the opportunity to use both, why choose only one?


Hydrozoa course 2022 edition – as told by our MSc student Ana González

Last month, our project NorHydro (together with ForBio Research School of Biosystematics and project MEDUSA) organized a course on diversity, systematics and biology of Hydrozoa at the Marine Biological Station in Espegrend. Fifteen participants from 9 different countries came all the way to Bergen to learn more about these intriguing animals, share their ideas and projects, and start new collaborations. We asked one of the youngest members of the group –our highly motivated student Ana González– to share with us her thoughts about the course and her experiences with her MSc project. This is what she had to say:

When I started my Master’s Degree of Marine Ecology at the University of the Balearic IslandsI already knew about the existence of hydrozoans, but I had no idea how interesting these animals actually were. After some discussions, a lot of reading, and a fair amount of looking at pictures of hydroids and hydromedusae, I decided to work with these inconspicuous invertebrates for my MSc project under the supervision of Dr Luis Martell (University Museum of Bergen) and Dr. Maria Capa (University of the Balearic Islands). My project aims to evaluate whether we can use the benthic communities of hydrozoans as bioindicators of anthropogenic impact on the easternmost coasts of Mallorca Island, in the Mediterranean Sea.

Me on a sampling day looking for benthic hydrozoans at the marine reserve of Cala Gat (top). A closer view of the hard substrates I sample in the marine reserve (bottom left). The common hydroid Monotheca obliqua growing on Posidonia oceanica (bottom right). Picture credits: Maria Capa and Ana González.

Coastal areas are an attractive place to live, and these habitats provide ecosystem services that contribute greatly to the economy of the world, but a bad management of them can generate important damages and drastic changes in the ecosystem. One way to monitor environmental impacts in these habitats is by observing the response of their biological communities, so for this project I decided to study the assemblages of benthic hydrozoans in two opposite sites with different levels of anthropogenic impact: a harbor and a marine reserve. Moreover, I am comparing the communities in different seasons of the year, and I will analyze the assemblages growing on hard substrates (like rocks) and also those growing on a very important Mediterranean soft substrate: the endemic seagrass Posidonia oceanica.

Some hydroids common in my study area are those belonging to genera Clytia (family Campanulariidae, left), Sertularella (family Sertularellidae, middle), and Aglaophenia (family Aglaopheniidae, right). Picture credits: Ana González.

At the beginning, working with benthic hydrozoans was very challenging for me since the specimens I find are easily overlooked if one is not searching carefully for them. But the more time I dedicate to observe these organisms, the more curious I became about their identity and dynamics, and the easier it was to recognize them in the samples. However, identifying hydrozoans is a difficult task and I realized early that I needed some help, so I was very happy when the opportunity arose to apply for the course “Diversity, Systematics and Biology of Hydrozoa” in Bergen. There, I had the chance to meet some of the leading scientific experts in the field that helped me understand better the taxonomy and ecology of these animals. I couldn’t have imagined how much I was going to learn during the different activities of the course, but at the end these organisms were able to catch my attention and time flew between lectures, sampling trips, and laboratory work. One aspect of the course that I particularly enjoyed is the fact that it brought together participants with different trajectories in science, and everybody was happy to share their experiences in the world of hydrozoan science.

We had all kinds of weather during the course: rain, sun, wind, and even snow! Picture credits: Lara Beckmann and Joan J Soto Àngel.

We had the chance to sample on board the UiB research vessel Hans Brattström and we collected several planktonic and benthic hydrozoans in the fjords around the Marine Station. After each sampling event, we went back to the lab to sort the samples, find the hydrozoans and identify them to species. The plankton samples were usually the first ones to be processed, since hydromedusae are quite fragile and they tend to suffer morphological damages after being sampled with a net. We tried to identify all specimens to species level, with the aid of the stereomicroscopes and scientific literature with identification keys that the curse provided. The benthic samples were placed in aquariums to keep the organisms alive and then each of us had the opportunity to observe the specimens in our own stereomicroscope.

A sampling day on board of RV Hans Brattström. Top left: deploying the plankton net. Top right: a full cod-end with plankton sample. Middle right: students and teachers ready to leave the pier. Bottom: benthos sampling with the triangular dredge. Picture credits: Lara Beckmann, Sabine Holst, Luis Martell

Top right and left: students and teachers at the laboratory, identifying hydrozoans. Bottom left: searching for hydromedusae and siphonophores in the plankton sample. Picture credits: Sabine Holst and Lara Beckmann.

All together, we were able to find and identify more than 40 species from all the main groups of hydrozoans, including siphonophores, trachylines, leptothecathes, and anthoathecates. Working with hydromedusae was new for me and I discovered that observing them was more challenging than identifying the polyps, but it was also interesting in its own way. The hydrozoans that caught my attention the most were the polyps from the suborder Capitata, because their morphology is very different from the hydroids that I have observed in my MSc project so far. Capitate hydroids don’t have a protective theca, they possess tentacles that end up in a ball of nematocysts (so-called capitate tentacles), and they are absent from almost all my samples from Mallorca, which are instead dominated by hydroids belonging to the Order Lepthothecata.

Top: Colony of Sarsia lovenii (Anthoathecata: Corynidae) with gonophores (i.e. reproductive buds on the polyp body). You can also see the capitate tentacles, which end in a ball of nematocysts and are typical for suborder Capitata. Bottom: Colony of Clava multicornis showing also gonophores on the polyp body, but with filiform (non-capitate) tentacles. Picture credits: Lara Beckmann (top), Joan J. Soto Àngel (bottom).

My interest for hydrozoans, the great set of experts we had as teachers, and the charismatic animals that we collected were the perfect combination for me to have an incredible experience in this course. I think that courses like these are an excellent opportunity for beginners to learn with experts from different parts of the world. Interacting with all of these amazing people was very rewarding at both cultural and scientific levels, and this whole experience motivated me to keep on studying these interesting animals that are a part of the complex functioning of our oceans.


On the Hunt for Tiny Polyps

Two weeks ago I had the chance to go field-sampling on the research vessel Hans Brattström. The sampling this time was focused on a broad range of marine invertebrates ranging from Hydrozoans, Bryozoans, Polychaetes, Phoronids and Brachiopods. I was especially on the hunt for polyps of the family Hydractiniidae (Cnidaria: Hydrozoa) that grow preferably on shells of molluscs or hermit-crabs. I was happy to look for new specimens for NorHydro and my master’s project, especially since opportunities to go field-sampling have been rare due to the covid-19 restrictions. The area of Bergen has been sampled quite well for the NorHydro project, but I was especially looking for rare species or species that haven’t been sampled before.

The first sampling for NorHydro this season – and with great conditions! Picture Credit: Lara Beckmann

To collect hydractiniids, we took bottom samples using a triangular dredge and a grab sampler. When the dredge gets back on board, the sample gets sorted on a large table on deck. Then the detailed search begins, and every stone and cranny gets inspected. The polyps I was looking for can be tiny, ranging from less than 1 mm up to 8 mm. The substrates that they grow on vary in size and shape, it can be crabs, molluscs but also algae or stones, often not larger than a few centimeters. So it isn’t an easy task to find the polyps in a freshly collected sample. Luckily I found several conspicuous hermit crabs and also one snail that I took back to the museum. At first, I didn’t see the polyps – only under the microscope in the museum laboratory I was able to see that hydractiniid colonies were growing on the shells.

Video: A polyp colony of the species Podocoryna areolata (Family Hydractiniidae). The polyps were growing on the shell of a living mollusc, probably of the species Steromphala cineraria. Video Credit: Lara Beckmann

One colony of the species Podocoryna areolata was growing on the shell of a living mollusk. The mollusk provides a nice substrate because the movements of the snail provide the polyps with more opportunities to encounter food. Also, the colony is protected by the small wrinkles of the shells surface where the polyps can hide. The polyps of this species are super difficult to measure, but most are smaller than 0.5 mm. When disturbed, the polyps shrink to small blobs even smaller than this. When relaxed, they can extend a bit longer in size. Especially the tentacles reach out to get hold of any potential food that swims by, such as small crustaceans. This species releases medusae, which can frequently be found in the plankton in this area.

A single polyp of the same colony of Podocoryna areolata. Picture Credit: Lara Beckmann

On shells inhabited by hermit crabs of the species Pagurus bernhardus, I found several colonies of a yet unidentified species of the genus Podocoryna. This species is very commonly found as polyp almost along the entire Norwegian coast. I’m still studying the specimen to figure out the correct identification. Since there is a lot of confusion in the hydractiniid taxonomy, I need to combine genetic information and morphology to overcome the existing problems in their identification and naming. The colony was reproductive and medusa buds were growing on it. Interestingly the medusa of this species is rarely found in the plankton.

Polyps of the genus Podocoryna. On the right are parts of the grasping claws visible belonging to the hermit crab Pagurus bernhardus. Picture Credit: Lara Beckmann

All over the colony were medusa buds. These are growing medusae, which will be released in the water when they are mature. The medusae can do what the colony itself can’t: releasing eggs and sperm and thus reproduce sexually. Picture Credit: Lara Beckmann

Besides the polyps, I found several other organisms living with the colonies on the shells including Crustaceans, Nudibranchia, Foraminiferans and other hydroids. The shells provide a home for a diverse range of marine life and it resembles a tiny forest. But it is not all peace and harmony in there, the smallest amphipods were quickly munched by the Podocoryna polyps. Those, in turn, get eaten by nudibranchs, that crawl on the colonies and some species feed specifically on hydroid polyps.

Video: An amphipod that lives on top of the hermit crab shell, walking through the colony of Podocoryna polyps. Video Credit: Lara Beckmann


I didn’t find any more hydrozoan species that were interesting for NorHydro during the sampling trip (at least not while scanning with the bare eye). But, I want to show one more very common species around Bergen –Ectopleura larynx– just because it is such a nice-looking hydrozoan. It even was reproductive and released its larvae right into my petri-dish. The small bulbs that grow between the polyp tentacles contain the larvae, which are called actinula. They break free and swim around, swinging their tiny tentacles until they will settle on a piece of algae for example, and grow to a large colony again.

The species Ectopleura larynx is a common species at the Norwegian coast. On the left the released larvae, called actinula. On the right a polyp that usually grows in a large colonies with up to a hundred polyps. Picture Credit: Lara Beckmann


You want to learn more about hydrozoans and why it is important to study them? Read more about it in my blog article for Ecology for the Masses: link.

Also, keep up with the activities of NorHydro here in the blog, on the project’s facebook page  and in Twitter with the hashtag #NorHydro.

Research Internship – Francesco

In the last part of 2019 Francesco Golin collaborated with us as an intern in project NorHydro. Francesco is a student at the University of Algarve, where he is enrolled in the International Master of Science in Marine Biological Resources (IMBRSea). We asked him about his internship and this is what he told us:

During the 2019 autumn semester I joined Luis Martell and Aino Hosia in project NorHydro as a research intern. My research contribution was aimed at finding how many species of the hydrozoan genus Euphysa are present in Norwegian waters, and how to define them morphologically and genetically. Euphysa is a common genus with 22 accepted species, but many of them are not easy to tell apart from each other, which is why we decided to implement an integrative approach for species delimitation including morphological and molecular analyses.

Some of the species of Euphysa occurring in Norway. From left to right: Euphysa aurata, Euphysa flammea, and Euphysa sp

Working on board during the cruise

My first mission as an intern was collecting some samples of Euphysa and other gelatinous organisms. Luckily, the opportunity to do so presented itself during the student cruise associated to BIO325, a course in which I participated as part of my studies at UiB.

During this cruise I used a light table to spot the tiny jellyfishes brought on board by the Multinet, then I placed them on a Petri dish and took pictures of them with a camera attached to a stereomicroscope, before transferring them to an Eppendorf tube filled with ethanol.

All these elements (the pictures of each organism, the associated sampling data, and the samples themselves) are needed for species delimitation of hydromedusae. The pictures are used to compare the morphology of different individuals and to identify important diagnostic characters (unfortunately, ethanol-fixed jellyfish are not useful for morphological analysis), while the ethanol-preserved samples are used to obtain DNA sequences.

The light table used to spot the gelatinous zooplankton

Some siphonophore parts are very transparent, and thus they are some of the most difficult animals to spot in plankton samples.

The hydrozoan Aglantha digitale (left) was very abundant in all my samples. Other cnidarians, such as this anthozoan larva (right) were also present.

My second mission consisted on gathering the original descriptions of the different species of Euphysa. This information is necessary if we want to understand what makes each species different, and will come handy when analyzing the individuals and their pictures collected on the field. Talking about species boundaries, I had the opportunity to attend a course on “Molecular Species Delimitation” offered by the University Museum. In this course I learned how to perform the analysis of DNA sequences for species delimitation, using some common software (MEGA and R) for this purpose. These are important tools that will allow us to assess the diversity of Euphysa in Norway, and together with the morphological analyses these data will help us determine if new species have to be described.

Now the semester has ended and my internship is over. Nevertheless, I hope my help was meaningful, as I want to continue being a part of this research project in the future. I will keep myself updated with the changes in the taxonomy of Euphysa, so I’m sure I will be able to join NorHydro again when I’ll come back to Bergen!


Door #7: New shipment of tissue samples for barcoding

In the upper right corner is a “plate”: the microplates with 96 wells where we deposit small tissue samples that are to be processed at the CCDB lab in Canada for NorBOL

On the third day of Christmas,
we sent eleven microplates away:
one plate cnidarians (A)
two with worms a-wriggle (B)
two plates of insects (C)
three plates crustaceans (D)
two (and a half) plates of mites (E)
and a half-plate assorted a-arthropods (F)!

Ahem. Yes.

As Endre explained in the fifth post of the calendar, collecting, identifying, documenting and keeping specimens used for DNA barcoding is an important part of what we do here at the invertebrate collections. Our mission in the NORBOL consortium is to produce DNA-barcodes, particularly for marine fauna in Norwegian waters and to make these barcodes available with open access to records and metadata in the BOLD database. These samples contribute to the building of a validated reference library of the genetic barcodes of the species found in Norway. You can search for different taxonomic groups here to see if they have been barcoded from Norwegian territory: Search NorBOL

The process is fairly straight forward (at least on paper!): Animals are collected and identified. Those species relevant for barcoding are selected, and a specimen (=1 animal) is chosen to be barcoded. We take a small tissue sample from the specimen, and keep the rest of the animal as the barcode voucher; if the need should arise to check if it really is what we initially thought, it is crucial to be able to go back and check the animal again. The tissue samples are collected in wells on a plate like the one pictured above, and the information about the animals – where they were collected, who collected them, what species they are, who identified them and so on is uploaded to BOLD together with images of the animals.

Representatives for the tissue sample plates that we just shipped off. Thank you Steffen, Anna and Per for contributing the terrestrial animals and images! Photos: L. Martell, A. Seniczak, S. Roth, K. Kongshavn. Illustration: K. Kongshavn

On Monday we shipped a new batch of plates – as (attempted) illustrated in song above.

Included is material from several of the Norwegian Taxonomy Initiative projects (artsprosjekt) that are happening at the University Museum of Bergen. We are coordinating the efforts on marine life, but are of course also facilitating the NorBOL barcoding of other organisms that take place at the UMB.  There are animals from NorAmph (Norwegian Amphipoda), Hydrozoan pelagic diversity in Norway (HYPNO), Orbatid mites, and the insects found associated with nutrient rich marshes in Hedmark in this shipment.

We have also prepared several plates of Crustaceans collected and identified by the Norwegian marine mapping programme Mareano – one of the great contributors of material to the collections.

Now we wait for the lab to process them, and for the genetic sequences to be uploaded to BOLD – fingers crossed for many interesting results!


Door #2: A glimpse of Hydrozoan anatomy

Hydroids and hydromedusae are abundant and widespread, but they can be difficult to identify, in part due to the overwhelming amount of terminology used to describe their polyps, colonies and medusae. The diversity of shapes and life cycle strategies in Hydrozoa is in fact so high that it is almost impossible to find a single set of descriptive terms for all species, and different glossaries have been developed for closely related families, sometimes genera, and also for the different stages in the life cycle of the same organism. To further complicate things, the terminology we use for the characterization of hydrozoan morphology has been adapted in many cases from other fields of science (like botany and geometry), and some of the words ended up with very different meanings depending of the organism we are looking at.

But if you are interested in these fascinating creatures, fear not! We at the invertebrate collections have thought about giving you a little visual aid in the form of four plates including some of the basic structures of hydroids and hydromedusa (courtesy of artsprosjekt HYPNO and upcoming artsprosjekt NORHYDRO).

Figure 1: Thecate polyps, like the ones of Aglaophenia harpago, are protected by rigid structures called “thecae” into which the polyp can retract. In many species they live all together forming colonies. Credit: Joan J. Soto Àngel and L. Martell.

Figure 2: Unlike their “protected” relatives, athecate polyps (e.g. those of Pennaria disticha) lack the skeletal protection of the theca, but can also form large colonies with many polyps. Credit: Joan J. Soto Àngel and L. Martell.

Figure 3: The hydromedusae produced by thecate polyps are called leptomedusae, and can be recognized by the development of gonads in the radial canals (among other characteristics). From left to right and top to bottom in the picture are three species present in Norwegian waters: Tiaropsis multicirrata, Modeeria rotunda, and Tima bairdii. Credit: L. Martell and A. Hosia, HYPNO project.

Figure 4: Anthomedusae (hydromedusae produced by athecate polyps) usually have the gonads developed in the manubrium. From left to right and top to bottom in the picture are Leuckartiara octona, Rathkea octopunctata, and Sarsia tubulosa. Credit: L. Martell and A. Hosia, HYPNO project.

Hopefully these images can be used as a starting point for the uninitiated, and why not? perhaps also as a source of inspiration for cool marine-related presents for the season!

-Luis Martell and Joan J. Soto Àngel