Category Archives: Artsprosjekt/NTI projects

Fieldwork with the SponGES project on R/V Kristine Bonnevie

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Greetings from the big, old blue!

We don’t have much internet out here, so updates will be sporadic – but here’s the tale of the first half of the two cruises that the Invertebrate Collections people have stowed away on this spring. The current cruise is part of the SponGES-project that is being coordinated by the University of Bergen, Norway (prof. Hans Tore Rapp).

We are currently midway in the six-day cruise (26th of April to 2nd of May), and are presently to be found at 59°63,000 N, 04°42,000 E – there are mountains on one horizon, and open ocean on the other. After a night of muddy (clay-y) sampling, the majority of us are relaxing and eagerly awaiting lunch, whilst some of the sponge-folks are huddled inside the big, blue container on the deck, surveying the sea floor with the ROV Aglantha (occasionally cherry-picking sponges with fancy scoops).

The ROV Aglantha, inside the Blue Box, and sponge-capturing device

The ROV Aglantha, inside the Blue Box, and sponge-capturing device

At present we are at station #33; it has been three busy days so far! This is the first trip for all of us on the “new” R/V Kristine Bonnevie (formerly known as “Dr. Fritjof Nansen”, but that name has passed on to the new Nansen vessel), and we’re thoroughly enjoying it. The crew is amazing, the food is delicious, and the samples keep coming – what’s not to like? Even the weather has been good to us most of the time – though we have sprouted quite a crop of anti-seasickness patches onboard by now!

#bestoffice

#bestoffice

We had to take a break to admire this

We had to take a break to admire this

Shenanigans on deck

Shenanigans on deck

In addition to the ROV, we are using van Veen grabs, Agassiz trawl, plankton net, and RP-sledge to collect fauna. We also stumbled across hundreds of meters of lost fishing line when diving with Aglantha – the operators were able to catch an end of it, and it was dragged onboard to be discarded properly. The rope was heavily colonized by sponges, hydrozoa and mussels, so we got a “bonus sample” from that – and we got to clear away some marine pollution. Win/win!

Old Fishing line being removed - and samples taken from it!

Old Fishing line being removed – and samples taken from it!

My main incentive for being onboard is to secure ethanol-fixed (=suitable for DNA work) material from locations that we have either none or only formaldehyde fixed. This will then become part of the museum collections – and we will have fresh material for DNA barcoding through NorBOL.

Ready to dive in!

Ready to dive in!

The art of washing grab samples - get rid of the mud, keep the animals intact!

The art of washing grab samples – get rid of the mud, keep the animals intact!

Scooping up top sediment from grabs for analyses

Scooping up top sediment from grabs for analyses

Incoming trawl

Incoming trawl

Sampling in the sunset

Sampling in the sunset

The samples we are collecting are gently and carefully treated on deck before being bulk (i.e. unsorted) fixated in ethanol. There is lab space onboard, but we don’t have the time to do much sorting here. It will be exciting to see what we find once we get back to the lab and begin sorting it!

Lab facilities onboard

Lab facilities onboard

But before we get to that, we have three more days with SponGES, and then we go on to the next cruise, which will also be with Bonnevie – this time we’re heading up and into the Sognefjord.

Stay tuned for updates!

-Katrine

ps: SponGES’ facebook page is here

AmphipodThursday: IceAGE-amphipods in the Polish woods

img_2610This adventure started 26 years ago, when two Norwegian benthos researchers (Torleiv Brattegard from University of Bergen and Jon-Arne Sneli from the University in Trondheim) teamed up with three Icelandic benthos specialists (Jörundur Svavarsson and Guðmundur V. Helgasson from University of Iceland and Guðmundur Guðmundsson from the Natural History Museum of Iceland) to study the seas surrounding the volcanic home of the Nordic sages. 19 cruises and 13 years later – and not least lots of exciting scientific findings and results the BioICE program was finished.

But science never stops. New methods are developed and old methods are improved – and the samples that were stored in formalin during the BioICE project can not be used easily for any genetic studies. They are, however, very good for examinations of the morphology of the many invertebrate species that were collected, and they are still a source of much interesting science.

Participants of the IceAGE workshop. Photo: Christian Bomholt (www.instagram.com/mcb_pictures)

Participants of the IceAGE workshop. Photo: Christian Bomholt (www.instagram.com/mcb_pictures)

The dream about samples that could be DNA-barcoded (and possibly examined further with molecular methods) lead to a new project being formed – IceAGE. A large inernational collaboration of scientists organised by researchers from the University of Hamburg (and still including researchers from both the University of Iceland and the University of Bergen) have been on two cruises (2011 and 2013) so far – and there is already lots of material to look at!


This week many of the researchers connected with the IceAGE project have gathered in Spała in Poland – at a researchstation in woods that are rumoured to be inhabited by bison and beavers (we didn´t see any, but we have seen the results of the beavers work). Some of us have discussed theories and technical stuff for the papers and reports that are to come from the project, and then there are “the coolest gang” – the amphipodologists. 10 scientists of this special “species” have gathered in two small labs in the field-station, and we have sorted and identified amphipods into the wee hours.

It is both fun and educational to work together. Everybody have their special families they like best, and little tricks to identify the difficult taxa, and so there is always somebody to ask when you don´t find out what you are looking at. Between the stories about amphipod-friends and old times we have friendly fights about who can eat the most chocolate, and we build dreams about the perfect amphipodologist holiday. Every now and then somebody will say “come look at this amazing amphipod I have under my scope now!” – we have all been treated to species we have never seen before, but maybe read about. We also have a box of those special amphipods – the “possibly a new species”- tubes. When there is a nice sample to examine, you might hear one of the amphipodologist hum a happy song, and when the sample is all amphipods but no legs or antennae (this can happen to samples stored in ethanol – they become brittle) you might hear frustrated “hrmpfing” before the chocolate is raided.

 

Isopodologists (Martina and Jörundur) visiting the amphipodologists... Photo: AH Tandberg

Isopodologists (Martina and Jörundur) visiting the amphipodologists… Photo: AH Tandberg

The samples from IceAGE are all stored in ethanol. This is done to preserve the DNA for molecular studies – studies that can give us new and exciting results to questions we have thought about for a long time, and to questions we maybe didn´t even know we needed asking. We can test if what looks like the same species really is the same species, and we can find out more about the biogeography of the different species and communities.

The geographical area covered by IceAGE borders to the geographical area covered by NorAmph and NorBOL, and it makes great sense to collaborate. This summer we will start with comparing DNA-barcodes of amphipods from the family Eusiridae from IceAGE and NorAmph. They are as good a starting-point as any, and they are beautiful (Eusirus holmii was described in the norwegian blog last summer).


Happy easter from all the amphiods and amphipodologists!

Anne Helene

Literature:

Brix S (2014) The IceAGE project – a follow up of BIOICE. Polish Polar Research 35, 1-10

Dauvin J−C, Alizier S, Weppe A, Guðmundsson G (2012) Diversity and zoogeography of Ice−
landic deep−sea Ampeliscidae (Crustacea: Amphipoda). Deep Sea Research Part I: 68: 12–23.

Svavarsson J (1994) Rannsóknir á hryggleysingjum botns umhverfis Ísland. Íslendingar og hafiđ.
Vísindafélag Íslendinga, Ráđstefnurit 4: 59–74.
Svavarsson J, Strömberg J−O,  Brattegard T (1993) The deep−sea asellote (Isopoda,
Crustacea) fauna of the Northern Seas: species composition, distributional patterns and origin. Journal of Biogeography 20: 537–555.

Door #23: How far away can a quill worm get?

Hyalinoecia tubicola from the North Sea (by K. Kongshavn).

Hyalinoecia tubicola from the North Sea (by K. Kongshavn).

Quill worms belong to the annelid family Onuphidae and are called like that because of their unique tubes. The tubes are secreted by their inhabitants and are very light and rigid, resembling a quill, the basal part of a bird’s feather used for writing. Quill worms are epibenthic creatures capable of crawling on the surface of the sea floor carrying their tubes along. Their anterior feet are modified, strengthened and enlarged, bearing thick and stout bristles. These anterior feet are used for locomotion.

Quill worms are widely distributed in the ocean inhabiting mostly slope depths down to 2000 m. Being large in body size (up to 10-20 cm long), they can be quite abundant in some areas. Meyer et al. (2016) reported Hyalinoecia artifex reaching up to 70 ind./m2 in the Baltimore Canyon at 400 m water depth. Another quill worm, H. tubicola, which is very common in Norwegian waters, reached up to 272 ind./m2 at 365 m offshore of Chesapeake Bay (Wigley & Emery 1967).

Quill worms are believed to be motile scavengers. Baited monster camera experiments performed at 2000 m deep site in Baja California demonstrated that Hyalinoecia worms can accumulate in hundreds of specimens five hours after the bait (rotten fish) has been deployed (Dayton & Hessler 1972). Myer et al. (2016) analyzed the stable isotope content in Hyalinoecia artifex tissues confirming its secondary consumer status. Their results supported earlier observations on the gut content of the same species by Gaston (1987) showing the presence of the remains of various benthic invertebrates.

Video 1. Quill worm Hyalinoecia tubicola moving inside its tube (by K. Kongshavn).

 

Video 2. Quill worm Hyalinoecia tubicola protruding from the tube opening. Three antennae and a pair of palps are seen on the head. The first two pairs of feet are enlarged and strengthened (by K. Kongshavn).

 

Dayton, P.K., Hessler, R.R., 1972. Role of biological disturbance in maintaining diversity in the deep sea. Deep-Sea Research 19: 199–208.

Meyer, K.S., Wagner, J.K.S., Ball, B., Turner, P.J., Young, C.M., Van Dover, C.L. 2016. Hyalinoecia artifex: Field notes on a charismatic and abundant epifaunal polychaete on the US Atlantic continental margin. Invertebrate Biology 135: 211–224. doi:10.1111/ivb.12132

Gaston, G.R. 1987. Benthic polychaeta of the Middle Atlantic Bight: feeding and distribution. Marine Ecology Progress Series 36: 251–262.

Wigley, R.L., Emery, K.O. 1967. Benthic animals, particularly Hyalinoecia (Annelida) and Ophiomusium (Echinodermata), in sea-bottom photographs from the continental slope. In: Deep-Sea Photography. Hersey JB, ed., pp. 235–250. John Hopkins Press, Baltimore.

-Nataliya

Door #22 A jolly, happy family?

Musculus discors hidden in Securiflustra securifrons. Photo: AHS Tandberg

Musculus discors hidden in Securiflustra securifrons. Photo: AHS Tandberg

At first glance, it can look like a seaweed. The depth, however, should start your alarm-bells for flora and point you towards fauna: the plantlike animal Securiflustra securifrons (Pallas, 1766) is a bryozoa – a collection of colonial filterfeeders less than 1 mm in size each. We are at 80-120 m depth in the cold Heleysundet – the sound between the two islands Spitsbergen and Barents Island in the eastern part of the Svalbard Archipelago. This is a sound famous among captains for its fast tidal streams, and the fast-flowing waters give the bryozoans a nice place to live. The colonies branch out to catch the most water-flow and the most food from the water.

Musculus discors. Photo: AHS Tandberg

Musculus discors. Photo: AHS Tandberg

Where the “branches”  form we see what might look like small hairy balls – these are the bivalve Musculus discors (L., 1767). The hairy look comes from their byssus threads – they produce and then use these threads to attach to the Securiflustra (and being packed in the threads they might get some camouflage from them).

 

Moving inside the molluscs we might find not only one, but two species of amphipods. In our samples from Heleysundet 14% of the Musculus had the carnivorous amphipod Anonyx nugax Ohlin, 1895 inside, and an astonishing 3 out of 4 Musculus had amphipods of the species Metopa glacialis (Krøyer, 1842) inside.  The system resembles a Russian doll – one species living inside another living inside yet another…

Anonyx affinis (large amphipod, upper left) and Metopa glacialis (small amphipod lower half og mussel) innside a Musculus discors. Photo: AHS Tandberg

Anonyx affinis (large amphipod, upper left) and Metopa glacialis (small amphipod lower half og mussel) innside a Musculus discors. Photo: AHS Tandberg

What reason can a small crustacean have to live inside the quite closed off world of a bivalve? The bivalve filters water actively – it pumps water over its gills, and then transports food-particles such as phytoplankton down the gills towards its mouth. Non-desirable particles are normally packed into mucus and transported out of the bivalve. Now imagine liking to eat some of those particles the bivalve finds non-desirable, and being placed on the gills of said bivalve. No need to hunt for the food – it will be coming on the conveyor-belt the gills are – and all you need to do is to eat. The bivalve does not seem to be troubled by this co-habitant – it does not eat the same food as the bivalve.

Not only does Musculus discors provide Metopa glacialis with food, the mantle cavity provides a luxury-shelter where the amphipod can raise a family! Amphipods, together with isopods, cumaceans, tanaidaeans and quite a few mysicadeans keep their offspring in a brood-pouch from the fertilisation of the eggs to the medium sized juveniles crawl out into the real world. Living inside a bivalve allows Metopa glacials to extend its child-care to young life outside the brood-pouch. Our examinations of the bivalves from Heleysundet showed us adult Metopa in the middle of the bivalve, with several juveniles “strategically placed” inbetween the two layers of gills in each shell-half. Surrounded by food, safe from most predators! (Predation of Metopa glacialis might be the main objective for Anonyx affinis, the food-source of the lysianassid needs to be established. It might also be the nice and fatty mollusk.)

 

Metopa glacialis innside a Musculus discors. Small arrows point to juveniles, large arrow to adult female. Photo: AHS Tandberg

Metopa glacialis innside a Musculus discors. Small arrows point to juveniles, large arrow to adult female. Photo: AHS Tandberg

Comparing with amphipods of the same size-range from the same areas, Metopa glacialis seems to have a safe life. Safe enough that they can manage to have several sets of offspring. We see that they don´t wait until´the first batch of kids are out of the “house” – we found one adult female with two size-groups of offspring and a fresh egg-filled brood-pouch!  Each batch can be 20 offspring, so that would mean one pregnant mom and 40 kids in one small house!

 

Many people travel to visit family during the holidays. Even when we cherish the time with our loved ones, filling the house with grandparents, aunts, uncles and cousins might cramp everybodys style slightly. Not so with Metopa glacialis. Measuring the size of all inhabitants show us that the kids stay home until they are adult and can move out to their own home. So when you can´t sleep because your younger cousin plays on her gamer all night, or because your old aunt snores when you come into your shared room, think how much more difficult life could have been if you were an amphipod. Happy holidays!

Anne Helene

PS: A slightly extended version in Norwegian (part of the TangloppeTorsdag blog) can be read here)

Literature:

Just J (1983) Anonyx affinis (Crust., Amphipoda: Lysianassidae), commensal in the bivalve Musculus laevigatus, with notes on Metopa glacialis (Amphipoda: Stenothoidae). Astarte 12, 69-74

Tandberg AHS, Schander C, Pleijel F (2010) First record of the association between the amphipod Metopa alderii and the bivalve Musculus. Marine Biodiversity Records 3:e5 doi:10.1017/S1755267209991102

Tandberg AHS, Vader W, Berge J (2010) Studies on the association of Metopa glacialis (Amphipoda, Crustacea) and Musculus discors (Mollusca, Mytilidae). Polar Biology 33, 1407-1418

Vader W, Beehler CL (1983) Metopa glacialis (Amphipoda, Stenothoidae) in the Barents and Beaufort Seas, and its association with the lamellibranchs Musculus niger and M. discors s. l. Astarte 12:57–61

Door #19: Going back to the roots

Last year we had a calendar post about the Heart of the Museum – our type collections.

To recap, a species’ type is “…the objective standard of reference for the application of zoological names. When a new species or subspecies is described, the specimen(s) on which the author based his/her description become the type(s) (Article 72.1). In this way names are linked to type specimens, which can be referred to later if there is doubt over the interpretation of that name.

Consequently types are sometimes referred to as “onomatophores” which means name bearers.”

– International Commission on Zoological Nomenclature (IZN)

The location – sampling site – from which the type specimen is described is known as the type locality.

Michael Sars (image from Wikimedia)

Michael Sars (image from Wikimedia)

As you have probably noticed, polychaetes (bristle worms) are a focus group in our lab, and several species have type localities close by.

The biologist and theologian Michael Sars (1805-1869) lived in the Bergen region for many years.  He was a prolific taxonomist, naming 277 species of marine taxa according to the World Register of Marine Species (WoRMS).

 

Consequently there are quite a few species that have their type locality within easy daytrip-distance by ship for us.

On the hunt with R/V "Hans Brattstrøm"

On the hunt with R/V “Hans Brattstrøm”

cover

One such locality is Glesvær, where Michael Sars described several new species in his work of 1835:  Beskrivelser og Iagttagelser over nogle mærkelige eller nye i Havet ved den Bergenske Kyst levende Dyr af Polypernes, Acalephernes, Radiaternes, Annelidernes og Molluskernes Classer* (“Descriptions and Observations of some strange or new animals found off the coast of Bergen, belonging to the Classes …”).

The polychaete Amphicteis gunneri (Ampharetidae) is one of these species. It was first described by Michael Sars as Amphitrite gunneri (the species name is an homage to Johan Ernst Gunnerus (1718-1773) who was an active scientist within botany and zoology,  as well as the bishop in Trondheim, and one of the founders of Det Kongelige Norske Videnskapers Selskap) in the publication above. Here are his original illustrations of the species:

gunneri

Amphicteis gunneri by M. Sars (1835)

We have previously submitted several specimens of Amphicteis gunneri for DNA-barcoding through the NorBOL-project – and found that specimens that according to the keys in the literature should all come out nicely as A. gunneri in fact end up in several barcode-based groupings (BINs), meaning that they genetically different from each other. Then we need to unravel which one is the true A. gunneri, and decide what to do with the others. In such cases, material from type localities is invaluable. By sending in specimens identified by resident taxonomists as A. gunneri from the type locality, we hope to figure out which BIN represent A. gunneri, and which represent potentially new species.

We were also able to photograph live specimens showing the nice coloration of this worm. Fixed specimens lose this colour and become uniformly yellow/white (no dots).

Amphicteis gunneri collected at type locality. Photo: K.Kongshavn

Amphicteis gunneri collected at type locality. Photo: K.Kongshavn

*Thanks to the excellent Biodiversity Heritage Library, this publication can be found in full text online, accessible for everyone – go here to see it. The Flickr stream of BHL is also an excellent source of amazing illustrations, you can find that here.

-Tom & Katrine

Door #15 Twinkle, twinkle, little animal?

Yesterdays door of this calendar introduced the bioluminescent animals of the deep sea.
In the parts of the ocean where sunlight reaches (the photic zone), production of ones own light is not common. This is because it is costly (energetically), and when the surroundings already are light, the effect is almost inexistent. An exception to this is the use of counter-illumination that some animals have: lights that when seen from underneath the animal camouflages them against the downwelling light from above.

But what then with the ocean during the polar night? Last Thursdays blog told the story of the dark upper waters during the constant dark of the arctic winter, and how the quite scanty light of the moon is enough to initiate vertical mass movements. Another thing we see in the dark ocean is that processes that at other latitudes are limited to the deep sea come up nearly to the surface during the polar night.

So – in the Arctic winter we don´t have to use robots and remote cameras to observe biioluminescent animals: we can often observe them using normal sport diving equipment or even from above the surface. A very recent study (Cronin et al, 2016) has measured the light from different communities in the Kongsfjord of Svalbard during the polar night. They found that going from the surface and down, dinoflagellates produced most light down to 20-40 m depth, the lighting “job” was then in general taken over by small copepods (Metridia longa). Most light was produced around 80 m depth.

Bioluminescent dinoflagellates shining through the winter sea ice in Kongsfjorden. Photo: Geir Johnsen, NTNU

Bioluminescent dinoflagellates shining through the winter sea ice in Kongsfjorden. Photo: Geir Johnsen, NTNU

It is possible to recognise different species from the light they make; a combination of the wavelength, the intensity and the length of the light-production gives a quite precise “thumbprint”. If we know the possible players of the system in addition, an instrument registering light will also be able to give us information about who blinks most often, at what depths, etc. Cronin and her coauthors have made a map of the lightmakers in the Kongsfjord.

Bioluminescence profiles from Kongsfjord. Figure 3 from Cronin et al, 2016

Bioluminescence profiles from Kongsfjord. Figure 3 from Cronin et al, 2016

This is all well and good, but the next question is of course WHY. There can be several uses for light, and we can bulk the different reasons into 3 main groups: Defense, offense and recognition.

Different strategies for Bioluminescence. Fig 7 from Haddock (2010), redrawn for representation of the Polar night bioluminescence by Ola Reibo for the exhibition "Polar Night"

Different strategies for Bioluminescence. Fig 7 from Haddock (2010), redrawn for representation of the Polar night bioluminescence by Ola Reibo for the exhibition “Polar Night”

 

The bioluminescent cloud from an escaping krill. Kongfjorden, during the Arctic polar night. Photo: Geir Johnsen, NTNU

The bioluminescent cloud from an escaping krill. Kongfjorden, during the Arctic polar night. Photo: Geir Johnsen, NTNU

Defence has already been mentioned above: the counterillumination against downwelling light is helping an animal defend itself against predation. Some will leave a smokescreen, or even detach a glowing bodypart while swimming away in the dark, and others blink to startle the enemy or to inform their group-mates that an enemy is getting close.

 

 

Offense is mainly to use the light to get food (this is typical angler-fish-behaviour), and recognition is very often about flirting. Instead of flashing your eyelashes at your your chosen potential partner, you flash some light at him or her…

Thursdays are about amphipods in this blog, so here they come. Bioluminescent amphipods are present mainly in the hyperiid genera Scina (a Norwegian representative of this genus is Scina borealis (Sars, 1883).) Hyperiids are amphipods that swim in the free watermasses, like most other bioluminescent animals.

The bioluminescent amphipod Scina borealis (Sars, 1893). The added stars indicate where the bioluminescence occurs. Original figure: G.O.Sars, 1895.

The bioluminescent amphipod Scina borealis (Sars, 1893). The added stars indicate where the bioluminescence occurs. Original figure: G.O.Sars, 1895.

Crustacea use more different ways to produce bioluminescence than most other groups – this points to a possibility that the use of bioluminescence has evolved several independent times in this group. So the copepod Metridia longa will use a different chemical reaction than the krill, and the amphipods use again (several) different reactions. Some research on the bioluminescence of amphipods was undertaken already in the late 1960s, where P Herring collected several Scina species and kept them alive in tanks. There he exposed them to several luminescence-inducing chemicals and to small electrical shocks, to see where on the body light was produced and in what sort of pattern. He reported that Scina has photocytes (lightproducing cells) on the antennae, on the long 5th “walkinglegs”, and on the urosome and uropods. They would produce a nonrythmical rapid blinking for up to 10 seconds if attacked, and at the same time the animal would go rigid in a “defence-stance” with the back straight, the antennae spread out in front of the head, and the urosome stretched to the back. This definitely seems to be a defence-ligthing, maybe we should even be so bold as to say it would startle a predator?

Anne Helene

Literature:

Cronin HA, Cohen JH, Berge J, Johnsen G, Moline MA (2016) Bioluminescence as an ecological factor during high Arctic polar night. Scientific Reports/Nature 6, article 36374 (DOI: 10.1038/srep36374)

Haddock SHD, Moline MA, Case JF (2010) Bioluminescence in the Sea. Annual Review of Marine Science 2, 443-493

Herring PJ (1981) Studies on bioluminescent marine amphipods. Journal of the Marine biological Association of the United Kingdoms 61, 161-176.

Johnsen G, Candeloro M, Berge J, Moline MA (2014) Glowing in the dark: Discriminating patterns of bioluminescence from different taxa during the Arctic polar night. Polar Biology 37, 707-713.

Door #12: All aboard the jelly cruise!

Travelling alone through the water column may be a dangerous business: reaching the final destination is not always guaranteed, the risk of being eaten is high, and even finding food may prove a difficult task… which is why several animals choose to travel comfortably on or inside jellyfish and siphonophores!

Jellyfish are commonly involved in relationships of parasitism and phoresis (i. e., when one organism is mechanically transported by another without any further physiological dependence), and many examples have been observed of these interactions around the world. For instance, it’s not unusual to find hyperiid amphipods and sea-spiders –as well as lobster and crab larvae – piggybacking on the surface of large and tiny jellyfish, and while it’s still not clear whether or not all these passengers feed on their means of transportation, real parasitism and jelly-feeding has been confirmed for at least some of them. Jellyfish may also transport parasitic worms to their final hosts (like the nematode you see in the pictures), acting as carriers of parasites towards fish and mammals, and sometimes, eventually reaching humans as well!

Euphysa aurata medusa with parasitic nematode larva. Korsfjord, February 2016. Credit: Aino Hosia.

Euphysa aurata medusa with parasitic nematode larva. Korsfjord, February 2016. Credit: Aino Hosia.

A close-up of 2 showing the parasite embedded in the mesoglea (jelly) of the host. Credit: Aino Hosia.

A close-up of 2 showing the parasite embedded in the mesoglea (jelly) of the host. Credit: Aino Hosia.

Euphysa aurata medusa with crustacean ectosymbiont. Raunefjord, December 2016. Credit: Luis Martell

Euphysa aurata medusa with crustacean ectosymbiont. Raunefjord, December 2016. Credit: Luis Martell

These two hydromedusae of Euphysa aurata were collected this year in the fjords south of Bergen, and are only an example of jellyfish harboring other animals in this area. The species is a common and widespread jellyfish around here, but its role in the transmission of parasites and transportation of small crustaceans has never been explored. It might well be that, together with its gelatinous relatives, E. aurata will prove to be involved in many more biological interactions than we previously thought!

Luis Martell

Door #10: Siphonophores

Today, I thought I’d introduce to you to a cool group of animals that is ubiquitous in the oceans (including the Norwegian seas), but unfamiliar to most people. Siphonophores (“kolonimaneter” in Norwegian) belong to cnidarians, a group that includes corals, anemones, hydroids and jellyfish, and is characterized by the presence of stinging cells used in prey capture. All siphonophores are predatory, and use their stinging tentacles to catch small crustaceans or, in the case of some species, even small fish.

The most (or only) familiar siphonophore for the majority of people is probably the highly venomous Portuguese Man O’War (Physalia physalis), which can be spotted floating on the surface of the ocean or stranded on beaches. However, it is not really representative of the group as a whole, as most siphonophores live in the water column of the open ocean rather than its surface. There are around 200 described species of siphonophores.

The most fascinating feature of siphonophores is their peculiar body plan. While siphonophores may appear to be a single animal, they are in fact a colony of physiologically connected and genetically identical but morphologically diverse individuals called zooids that have specialized to carry out different tasks for the colony. Siphonophores belong to the class Hydrozoa (“polyppdyr” in Norwegian), which covers two basic body plans: the polyp/hydroid and the medusa.

Schematic of a physonect siphonophore. From http://www.siphonophores.org (CC-by-nc-sa)

Schematic of a physonect siphonophore. From http://www.siphonophores.org (CC-by-nc-sa)

The various zooids comprising a siphonophore colony can also be divided into these main groups. For example, the zooids used for swimming, called nectophores, are medusoid, while the feeding zooids, or gastrozooids, are polyp-like. The siphonophore colony can also include specialized defensive, protective and reproductive zooids. All the zooids forming a colony arise by budding from a single fertilized egg. The different zooids are specialized to the degree that they cannot function as individual animals any more, and are only able to perform their specific tasks as parts of the siphonophore colony.

Anterior nectophore, posterior nectophore and eudoxid of the calycophoran siphonophore Dimophyes arctica – a common species in Norwegian waters. Photos by Aino Hosia (cc-by-sa)

Anterior nectophore, posterior nectophore and eudoxid of the calycophoran siphonophore Dimophyes arctica – a common species in Norwegian waters. Photos by Aino Hosia (cc-by-sa)

The zooids, for example the swimming nectophores, vary in appearance between species, and can be used for species identification. In addition, the various types of zooids in the colony are arranged in a strict species specific pattern, providing the intact colonies of each species with their particular appearance. While the individual zooids are generally small, millimeters to centimeters in size, some siphonophore species, like Praya dubia, may have colonies that reach 40 m in length! Siphonophore colonies generally have a zone of one or more (up to several dozen) swimming nectophores at the front, used to pull the colony through water. Behind this nectosome is the siphosome, which contains the feeding, reproductive and other zooids in a repeating pattern, each iteration of which is called a cormidium. In some species (suborder Calycophorae), these cormidia are released as small free-living reproductive colonies called eudoxids. Unfortunately, siphonophore colonies are extremely fragile and tend to fall apart during standard plankton sampling with nets, leaving behind a bewildering array of small bits and pieces – part of the reason they are relatively poorly known to most people.

Colony of physonect siphonophore Physophora hydrostatica, aka hula skirt siphonophore. Photo by Aino Hosia (cc-by-sa)

Colony of physonect siphonophore Physophora hydrostatica, aka hula skirt siphonophore. Photo by Aino Hosia (cc-by-sa)

Intact siphonophore colonies are beautiful, but often utterly alien in appearance. It is interesting to consider where to draw the line between an individual and a colony. While we as individuals have specialized organs to carry out our various bodily functions, siphonophore colonies are made up of specialized interdependent individuals or zooids similarly carrying out their specific tasks.

As part of project HYPNO we are charting the diversity of pelagic hydrozoans, including siphonophores, in Norway. There are ~15 species observed in Norwegian waters, and some, particularly Dimophyes arctica, Lensia conoidea and Nanomia sp. are extremely common components of marine plankton. However, siphonophores are primarily noticed when they become a nuisance: For example, mass occurrences of Muggiaea atlantica and Apolemia uvaria have in the past killed large numbers of farmed fish in Norway, with resulting losses to aquaculture companies.

– Aino (HYPNO)

Intrigued by siphonophores? For more information, visit e.g. http://www.siphonophores.org/  by Casey Dunn.

Door #8: the ups and downs of a marine werewolf?

When we think about what drives the ecosystems, much of the initial responsibility is put on the sunlight. This is mainly because of the photosynthesis, and thus the basic pieces of almost all food-webs, but light is also important for the animals. Many animals use visual cues to find food, and whether you search for food or do not want to become food, the presence (or absence) of light will help you.

Themisto sp swims up into the dark night. Photo: Geir Johnsen, NTNU

Themisto sp swims up into the dark night. Photo: Geir Johnsen, NTNU

Seawater is a pretty good stopper of light. We don’t need to dive far down before we are in what we consider a dark place, and less and less light finds its way the deeper we come. We tend to call the depths between 200 and 1000 m “the twilight zone”: most light stops way before 200m and the last straggling lumens give up at 1000m.

Most places on earth has a daily division between a dark and a light period: night and day. This is the ultimate reason for what is often called “the largest motion on earth”: Millions of zooplankton hide out in the darker parts of the water column during the day, and then move up to feed on the plants living in the light-affected parts of the water during the night (when predators will have a hard time seeing them). This daily commute up and down is called Diel Vertical Migration (DVM).

Themisto sp among the many smaller particles. (The light in this picture is from a flash). Photo: Geir Johnsen, NTNU

Themisto sp among the many smaller particles. (The light in this picture is from a flash). Photo: Geir Johnsen, NTNU

But what about the waters north of the polar circle? These areas will for some time during the winter have days when the sun stays under the horizon the entire day – this is “the Dark time” (Mørketid). At higher latitudes, there will be several days, or even weeks or months when the sun is so far below the horizon that not even the slightest sunset-glow is visible at any time. In this region, we have long thought that the Dark time must be a dead or dormant time.

 

The acoustic signals that gave the first indications of LVM. Figure 2 from Last et al 2016.

The acoustic signals that gave the first indications of LVM. Figure 2 from Last et al 2016.

We could not have been more wrong! It turns out that during the polar night, the DVM moves from being on a 24 hr cycle (sunlight-induced), to a 24.8 hour cycle! What is now the driver? The moon !(The lunar day is 24.8 hrs). Another thing that shows us that the moon must give strong enough light that predators can hunt by it, is that every 29.5 days most of the zooplankton sinks down to a depth of 50m: this falls together with the moon being full. Researchers have started to call this LVM (Lunar-day Vertical Migration) to show the difference to the “normal” DVM. There are of course lots of complicated details such as the moons altitude above the horizon and its phase that influences the LVM, but in general we can say that during the polar night (the Very Dark time), the “day” as decided by light has become slightly longer than normal.

The full moon, photographed by the Apollo 11 crew after their visit. Photo: NASA, 1969

The full moon, photographed by the Apollo 11 crew after their visit. Photo: NASA, 1969

Themisto - the werewolf. Note that the whole head is dominated by eyes - this is a visual hunter! Photo: Geir Johnsen, NTNU

Themisto – the werewolf. Note that the whole head is dominated by eyes – this is a visual hunter! Photo: Geir Johnsen, NTNU

Some of the larger animals taking part in the LVM are the amphipods Themisto abyssorum and Themisto libellula. They are hunters – so their reason to migrate up in the water column is not the plants, but the animals eating the plants; their favourite food are copepods of the genus Calanus. These are nice and quite energy-rich small crustaceans that eat the microscopic plants in the upper water column. We have sampled both Themisto-species in the middle of the winter (january), and their guts were filled to the brim with Calanus, so we know that they continue hunting by moon-light. They are such voracious hunters that some researchers have started to call them marine werewolves: the moonlight transforms them from sedate crustaceans to scary killers…

 

But, if they are the hunters, why do they spend so much time in the deep and dark during the lighter parts of the day? The hunters are of course also hunted. Fish such as polar cod (Boreogadus saida),  birds such as little auk (Alle alle) and various seals like to have their fill of the Themisto species. So – life has its ups and downs, and the dance of hunter and hunted continues into the dark polar night…

Anne Helene

Literature:

Berge J, Cottier F, Last KS et al (2009) Diel vertical migration of Arctic zooplankton during the polar night. Biology Letters 5, 69-72.

Berge J, Renaud PE, Darnis G et al (2015) In the dark: A review of ecosystem processes during the Arctic polar night. Progress in Oceanography 139, 258-271.

Kintisch E (2016)  Voyage into darkness. Science 351, 1254-1257

Kraft A, Berge J, Varpe Ø, Falk-Petersen S (2013) Feeding in Arctic darkness: mid-winter diet of the pelagic amphipods Themisto abyssorum and T. libellula. Marine Biology 160, 241-248.

Last KS, Hobbs L, Berge J, Brierley AS, Cottier F (2016) Moonlight Drives Ocean-Scale Mass Vertical Migration of Zooplankton during the Arctic Winter. Current Biology 26, 244-251.

Door # 6: Stuffed Syllid

Todays calendar critter is a Trypanosyllis sp. – a undescribed species from the genera Trypanosyllis in the family Syllidae. It most closely resembles a species described from the Mediterranean Sea. The Norwegian species is common in coral rubble, and has been assumed to be the same species as the one described from the Mediterranean. Genetic work reveals that these two are in fact separate species, and thus the Norwegian one is a new species awaiting formal description and naming. (If you read Norwegian, you can learn more about how species are described and named here: Slik gir vi navn til nye arter).

A new species of Trypanosyllis, collected in Sletvik, Norway. Photo by Arne Nygren. CC-by-sa

A new species of Trypanosyllis, collected in Sletvik, Norway. Photo by Arne Nygren. CC-by-sa

This specimen was collected, identified and photographed by Arne Nygren during our field work in Sletvik as part of his work on cryptic polychate species in Norway.

Syllids have opted for a rather fascinating way of ensuring high fertilization rates; something called epitoky: they asexually produce a special individual – the epitokous individual – from their bodies, and release this to go swimming in search of a mate. In the photo you can see that the female reproductive body (epitoke) is filled with orange eggs and has its own set of eyes, close to the middle of the animal. This section will break away from the mother animal and swim away in search of a male reproductive body to reproduce with. The mother animal will then grow a new female reproductive body.

-Arne & Katrine