Door # 18: MSc completed

Congratulations to Jenni, our (former!) master student, who presented her MSc project last Friday!

She has been working on the phylogenetic systematics and evolution of a genus of small marine gastropods called Phanerophthalmus, and she’s done an impressive amount of work.

Phanerophthalmus crawling on seagrass. Photo: M. Malaquias

The project was titled
Systematics, biogeography, and trophic ecology of the genus
Phanerophthalmus A. Adams, 1850 (Mollusca, Cephalaspidea, Haminoeidae) in
the Indo-West Pacific, and was supervised by Manuel Malaquias.

Celebrating our freshly minted MSC with coffee, cakes and bubbles

Celebrating our freshly minted MSC (second from the left in top photo) with coffee, cake and bubbles!

We wish you all the best, Jenni!

Door #17: New master student

Polina

Polina Borisova, a first year master student from the Zoological Department of the Moscow State University (Russia), is coming to the Invertebrate Collections of the University Museum of Bergen with a 1-month research visit in January 2017.

Polina is going to work on the bristle worms from the family Lumbrineridae studying the collection from West Africa and Norway. Her project is jointly supervised by Dr. Nataliya Budaeva from the University Museum of Bergen and Dr. Alexander Tzetlin from the Moscow University.

Various Lumbrineridae from West Africa, scale 1 mm (Photos from BOLD).

Lumbrineridae are the worms with relatively poor external morphology but complex jaw apparatus. The structure of jaws has been traditionally used in the systematics of the family in the generic diagnoses. Polina is utilizing the methods of microCT to study the jaws of lumbrinerids in 3D.

Jaws of Scoletoma fragilis from the White Sea scanned using microCT showing ventral solid mandibles, forceps-like maxillae I and denticulate maxillae II and II, carriers of maxillae are omitted (Photo: P. Borisova)

Polina is also going to sequence several genetic markers to reconstruct the first molecular phylogeny of the family. This will allow testing the current hypothesis on the intergeneric relationships within Lumbrineridae and will aid in tracing the evolution of jaws within the family.

-Nataliya & Polina

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

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

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

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 #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

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

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”

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.

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 #14: Where the sun doesn’t shine. Lucifer, luciferin and luciferase

Yesterday’s blog was about about Lucia, the mythical virgin who is celebrated with lights produced from combustion energy in candle lights. Lucia’s name is derived from the latin lux, meaning light. Similarly, Lucifer was one who was carrying light. We will not dwell with the ridiculous lore about Lucifer in old folk beliefs. Instead we will briefly look at real carriers of light from the organic world. Light can also be produced with other processes than fire and a range of organisms are particularly skilled in “letting there be light” in their environments. This is what we call bioluminescence. Bioluminescent substance can be used by potential prey animals to scare away predators. (Hover over picture with your mouse to see the gif.)

“Glow worm” beetles or “fire flies” of the families Lampyridae and Phengodidae are familiar to most people who have been out-door on a dark summer night. Studies of fire fly behavior have revealed how different species of these beetles communicate with their kinds using flash signals with variable frequency, intensity and duration. The biochemical mechanisms at work during bioluminescence are also relatively well studied in these beetle groups.

In the marine environments bioluminescence is known from many unrelated organisms and because different molecular reactions are involved in light production it is likely that bioluminescence must have evolved independently many times. A glowing sea may be experienced when massive densities of dinoflagellates are flashing their lights on the coast at night. Particularly Noctiluca scintillans, whose body is big enough to be visible with the naked eye, is frequently referred to in field guides to marine shore life. But many dinoflagellate species are involved in the bioluminescence that Norwegians call “morild”, – the “fire in the sea”. This phenomenon has also been called phosphorescence, however this is the process where light energy is absorbed by a substance and emitted on a different wave length. Special fluorescent proteins are responsible for glow-stick effects in organisms. (Incidentally the Greek light-carrier Phosphorus has been equated with the Latin Lucifer, and those of us who have seen white phosphorous in action understand what gave the name to this very reactive version of the element.) Studies of dinoflagellates have associated the light production with molecular bodies named scintillons and demonstrated that the biochemical activity in these objects in diatoms is governed by diurnal rhythms. This appears to make sense, because what is the point of flashing lights at day time? It may not be quite clear what use the diatoms have of producing light at night time either. However, it seems more obvious that there are functional advantages of bioluminescence in the depth of the ocean, where light does not penetrate. And it is below the so-called euphotic zone, from approximately 200 m on that bioluminescence is effective in different sorts of interactions among various animal groups. Deep water angler fish even use lit lures to attract prey.

Light emission in some animals is based on symbiosis with bacteria such as Aliivibrio fischeri. In other cases, the animal itself may produce the active proteins. Different biochemical systems are at work in bioluminescence and the light-producing molecules are not the same in all systems. Still, as a group of oxidizing and light emitting molecules they all go by the name of luciferin. To produce a light flash a catalyzing agent is also needed. This is provided by a group of different enzymes called luciferase. Other active components and free ions may be involved in the reaction which may be triggered in different ways, either mechanically as with a set of oars and a rowboat when dinoflagellates are near the surface water, or by some biochemical trigger. Sometimes it must happen by some neural response in the animal.

Light organs in the lantern fish Benthosema glaciale. (from Paulsen et al. 2013)

The lantern fishes are known for their photophores, – series of small organs that can produce yellow, green or blue light. Because the arrangement of photophores is different in different species, the organs are thought to play a role in communication between con-specific individuals. This may be the case for other animals as well, such as squids. It is also believed that the light organs can have a camouflaging effect by visually breaking up the silhouette of the fish, when the fish is viewed against a lighter back-ground higher up in the water column. The fish thus obtains protection from predators below by means of counter-illumination.

Several deep water animals are confusing potential predators by ejecting a luminescent substance towards the predator. Shrimps of the family Oplophoridae are particularly known to exercise this defensive technique. The luciferine in shrimps is called coelenterazine and is presumably produced in the digestive gland called haepatopancreas. When the shrimp spews the glow through the mouth, the effect is somewhat similar to the one that cephalopods use when they disappear in a cloud of ink. May we call it a “lucifer smoke-screen”?

Our museum collections have a rich material of these shrimps. Several species were collected during the MAR-ECO cruises over the Mid-Atlantic Ridge. One of them was Oplophorus spinosus shown in the picture below. While all of the oplophorids appear to be able to use a “lucifer smoke”, some of the species, including O. spinosus, also have light producing organs along their sides, somewhat similar to what we see in the lantern fishes. These photophores are complicated light generating organs with lenses and reflectors. They may be able to filter the wave length, and also the intensity and direction of the emitted light. In oplophorids, such organs are only found in three of the most closely related genera of the family, according to a recent study by Wong et al. (2015). Interestingly, these animals also have two types of eye pigments. One type is shared with other oplophorids and is sensitive to the blue-green part of the light specter. The other pigment is also sensitive to the shorter wave length in UV light. Because of the special abilities of the eyes it is tempting to think that these shrimps somehow are using the photophores in communication with individuals of their species. If so, Oplophorus spinosus and similar light talk would be a perfect case for biosemiotics. “Please shrimp, tell us about the world view from your perspective!” However, it is possible that the use of the photophores is only for counter-illumination when the shrimps are performing vertical migrations in the water column.

Oplophorus spinosus - a bioluminescent mid water shrimp (Photo: David Shale, MAR-ECO)

Oplophorus spinosus – a bioluminescent mid-water shrimp carrying large eggs (Photo: David Shale, MAR-ECO).

The “signalling abilities” of bioluminescent compounds are exploited in biotechnology and cell research. Luciferase from Oplophorus has been exploited as a so-called reporter gene in visualization of cell activities and gene transcription. May be it is not too far-fetched to see the shrimps as some kind of “light-carriers”.

Papers

Inoue S, Kakoi H, Goto T. (1976) Oplophorus luciferin, Bioluminescent substance of the Decapod shrimps, Oplophorus spinosus and Heterocarpus laevigatus. J.C.S. Chem. Comm. 966:1056-1057.

Poulsen JY, Byrkjedal I, Willassen E, Rees DJ, Takeshima H, Satoh TP, Shinohara G, Nishida M, Miya M. (2013).Mitogenomic sequences and evidence from unique gene rearrangements corroborate evolutionary relationships of Myctophiformes (Neoteleostei). BMC Evolutionary Biology 13:111.

Shimomura O, Masugi T, Johnson FH, Hanedal Y. (1978) Properties and reaction mechanism of the bioluminescence system of the deep-sea shrimp Oplophorus gracilorostris. Biochemistry 17:994-998.

Wong JM, Pérez-Moreno JL, Chan T.-Y, Frank TM, Bracken-Grissom HD. (2015) Phylogenetic and transcriptomic analyses reveal the evolution of bioluminescence and light detection in marine deep-sea shrimps of the family Oplophoridae (Crustacea: Decapoda). Molecular Phylogenetics and Evolution 83:278–292

Door #13: Lucia – with a ray of enlightenment?

Many kids will appear as “lucifers” today – light bearers. Celebration of Santa Lucia’s day seems to have won increasing popularity in Norway over the recent decades. Much of this cultural practice has clearly spread from Sweden, where the tradition is so deeply rooted since early 1900 that Swedish racists seem to believe that Lucia was an Arian blonde from remote mythical times of Astrid Lindgren’s Småland? But according to legend, Lucia was a christian martyr from Sicily in the fourth century. The story goes that she was tortured because of her conviction. She obtained her post mortem status as a heroine because she sacrificed her eyes for the “true faith” and was thus expelled to the darkness.

“Lussekatt” is a pastry made for Santa Lucia day. Is it supposed to express the track of the sun through the year?

Norwegian Wikipedia (of “Luciadagen”) claims that Lucia day has no actual association with Advent. “It is simply a celebration in commemoration of Sta. Lucia’s death on the 13th of December”, it is stated. But wait a minute! Take some time to look at the two calendars from the year 1700 that I reconstructed with the Timeanddate facility. This was the year when the Gregorian calendar revision was finally introduced in Denmark-Norway. Until that time Scandinavians had used the calendar that Julian Caesar’s government introduced 45 BC.

Reconstructed calendars for Denmark-Norway and Sweden from the year 1700. Notice that Norwegian Christmas Eve and Swedish Santa Lucia day are on the same day,

The Julian calendar is assuming a mean year length of 365.25 days, so the Julian clock was ticking about 20 minutes too fast compared to the mean tropical year. The Earth moves around the sun with a speed of about 30 km per second. As observed from the Earth, the mean time it takes for the Sun to return to the same point in the annual revolution is the tropical year. Revolution time is slightly variable, but since it is closer to 365.24 than to 365.25 the mismatch between the calendar and the season was increasing one day about every 128 years. In order to correct for the 10 days accumulated difference, the new Gregorian calendar was introduced in the catholic world in 1582.

Protestant Scandinavian countries may not have been able to discriminate between science and catholic religious practices. They delayed any action with the calendar until 1700 when the seasonal anomaly had increased to 11 days. In Denmark-Norway it was decided to delete those 11 days from the last part of February so that March 1st would follow immediately after February 18. The Swedes decided to go for a more gradual procedure. They reckoned that the calendar would be in order with time if they just neglected some successive leap years and skipped February 29 for some time. So they took this first small step by deleting February 29 in 1700. You can see how that worked out for February in the two calendars.

Travelling across the Norwegian-Swedish border in 1700 would imply the crossing of “multiple date lines”. Although it is questionable whether Lucia was celebrated to any extent in Sweden at the time, we could imagine that we wanted to travel there to take part in the feast for this catholic saint on the 13th of December. The Swedish calendar would show that Lucia is the fourth day in week number 50, which was a Thursday. However, the fourth day of week 50 in Norway was the 23rd. If we remember that the adjustment to the Gregorian calendar in 1700 should imply deletion of 11 days and that Sweden only got rid of one of those, we should rather consider the fifth day of week 50, namely Friday the 24th as the one that compares to Lucia day in Sweden. So with a couple of not particularly magic calculations we have matched Lucia’s deathday with Christmas Eve!
Could it be that these two mythical celebrations are actually rooted in fancy human imagination spun around the same astronomical event? Certainly so because in the course of time the Julian date for the winter solstice changed from 23rd to 22nd in the first centuries and in the 13th century the happening was down to 13th of December. This is the simple explanation to why some are confused by the fact that Lucia’s day is also called the darkest day of the year. Well, dear Swedes and sweet-hearts. Not any more.
We know that winter solstice, the day when the track of the sun has reached its southernmost point at the moving Tropic of Capricorn, was measured already 5000 years ago by stone age people at Newgrange in Ireland. During the regime of Julius Caesar the winter solstice was dated by Roman astronomers to December 25th and this became the celebration of the sun god Sol Invictus in the Roman Empire. However, the list of solar deities in pre-Cristian cultures is a long one and celebrations of winter solstice were significant in many pagan traditions before the customs were absorbed by Christian ways. Various brands of mystics still seem to recognize winter solstice as a moment of great spiritual significance. But maybe it would be sobering to think of the phenomenon in terms of solar energy influx and the amazing cascading biological effects of the seasons. In biology is where the mysteries are. Indeed the solstice marks an ecological and existential turning point for life on the northern hemisphere. At times it was dated to the 13th of December. This year it is happening on December 21st at 11:44.

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.

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

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 #11 Invertebrately inspired art?

Scientific illustrations today are usually formed within quite strict limits. We use photographs or drawings of small details, and these are all connected to one specific specimen that preferably is to be found in a scientific collection.

But can other approaches also help us? The artist Pippip Ferner has long found her inspiration in nature, and especially the (marine) invertebrates. Maybe her pictures can inspire us to examine other details in our study-animals? Maybe a picture can inspire you to think more about nature, the sea, or invertebrates – their lives and lores? These are not pictures that are meant to be scientifically accurate, but rather fabulations inspired by the wild things that happen when evolution gets to do as it pleases…

Some of Pippis drawings are inspired from scientific drawings, both old and new, some are from animals we have looked at together.

Here are some of Pippips pictures from this year, and the animals that inspired them. These three pictures were chosen to be part of the Evolution and Art section of the international science conference Evolution this summer in Austin, TX.

“Tunicate anatomy” (c) Pippip Ferner

Pippip says about this first picture:

“A scientific illustration of a TUNICATE is the inspiration for this work. Tunicates are sort of last stage before vertebrates. Clues for this is found in the larva that has a notochord, comparable to the spine of vertebrates. It has cerebral vesicle equivalent to a vertebrate’s brain, sensory organs that includes an eyespot to detect light and an otolith, which helps the animal orient to the gravity.
Fascinated by the thought of this “slimy blob” having many features similar to humans resulted in this quite complex outcome. The overload of insistent lines has given the tunicate quite a sophisticated system.”

Komodo National Park sea squirt (Polycarpa aurata). Photo: Nick Hobgood (wikipedia)

On the left is a photo of a live tunicate. This photo is from Indonesia, but tunicates are common to find also in our colder waters. They can be solitary as this one, or colonial – where several tunicates form a colony together by budding, so that one large colony basically has the exact same DNA. Most tunicates are sessile (they sit attached to one place), but some live floating around in the water. The best known of these pelagic tunicates are the salps of the southern oceans.

Internal anatomy of a tunicate (Urochordata). Adapted, with permission, from an outline drawing available on BIODIDAC. (Wikipedia)

A scientific illustration of a tunicate in a Biology textbook will look something like this:

Moving to other invertebrates, Pippip has worked with clams:

“Bivalve anatomy” (c) Pippip Ferner

“In this image I question how the clam lives in symbiosis with other species as its shell gets weaker due to climate changes. The drawing might resemble the results of some kind of scientific inquiry with references to the anatomy of a clam (bivalve).
In my work I let my own artistic evolutionary process make the clam into something more abstract.”

(If you wait until door # 22, there might be a story that relates to bivalves that live with others…)

This is a Ctenophore, a comb jelly:

“Comb jelly anatomy” (c) Pippip Ferner

“The starting point of this work was a detailed illustration from biologist Ernst Haeckel’s (Artforms in Nature) of a comb jelly/ctenophorae. The comb jelly differs from other jellyfish with more sophisticated nervous system with both synapses and individual muscle cells.
The outcome of this drawing is a tribute to the beauty of the structure of this organism.”

: The comb jelly Pleurobrachia pileus. Photo: Aino Hosia

: The comb jelly Mnemiopsis leidyi. Photo: Aino Hosia

: The comb jelly Beroe abyssicola. Photo: Aino Hosia

Jelly fishes anf Comb jelly fishes. Illustration: Ernst Haeckel, Kunstformen der Natur 1904, plate 27

Ctenophores are predatory planktonic jellies. The special thing about them, according to our Jelly-specialist Aino, is that they have a rotational symmetry. The diagnostic feature of comb jellies are their comb-rows that they use for swimming. The photos above represent the three groups of comb jellies – all of them are present in Norway.

To the right is the Haeckel-picture she started from, and here is a film of Comb jellies from the Chicago Shedd Aquarium.

Pippip, Anne Helene and Aino

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)

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)

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)

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 #9: Research stay of Juan Moles

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).

: Philine specimens

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:

: Gizzard plate

: Radula

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.

: Onchidoris muricata

: Limacia clavigera

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

The Invertebrate Collections

The University Museum of Bergen