Category Archives: 2016 december calendar

Door #4: A spindly Sunday

One of the cool things with the NorBOL-project is that it allows us spotlight animal groups that we don’t normally get to do much with. One such group is the sea spiders, or Pycnogonida. These spider-like critters wander around on the seafloor looking for other invertebrates to snack on (some also live on detritus and algae), and (presumably) for love. I certainly find a lot of them carrying egg sacks and young ones, so they must succeed every now and then! In the Pycnogonida, it is the males who care for the laid eggs and the young, rolling the eggs into one or several balls that he carries around on his ovigers.

The ones I photographed ranged from tiny to over 30 cm:

Colossendeis angusta, collected by MAREANO - this is bigger than a handful

Colossendeis angusta, collected by MAREANO – this is bigger than a handful

Ammothea echinata from the day when we joined the local student dive club - the animal is only a few mm

Ammothea echinata from the day when we joined the local student dive club – the animal is only a few mm

Anatomy of a pycnogonid: A: head; B: thorax; C: abdomen 1: proboscis; 2: chelifores; 3: palps; 4: ovigers; 5: egg sacs; 6a–6d: four pairs of legs Sars, G. O. (1895). An account of the Crustacea of Norway, with short descriptions and figures of all the species. Christiania, Copenhagen, A. Cammermeyer. L. Fdez (LP) – digitization and colouration. - Own work External anatomy of Nymphon sea spider. After G. O. Sars (1895).

Anatomy of a pycnogonid: A: head; B: thorax; C: abdomen 1: proboscis; 2: chelifores; 3: palps; 4: ovigers; 5: egg sacs; 6a–6d: four pairs of legs  L. Fdez (LP) – digitization and colouration. – Own work based on External anatomy of Nymphon sea spider. After G. O. Sars (1895).

At first glance they look a lot like the spiders we find on land, but they are really a very different class of animals (literally!); The sea spiders are found within  Checked: verified by a taxonomic editorAnimalia (Kingdom) > Checked: verified by a taxonomic editorArthropoda (Phylum) > Checked: verified by a taxonomic editorChelicerata (Subphylum) > Checked: verified by a taxonomic editorPycnogonida (Class) (from WoRMS), whilst “land spiders” are found within the order Aranea in the class Arachnida.

Extant (now-living) members of the Pycnogonida are found within the order Pantopoda, which translates into “all legs”, which describes them quite well! They have even moved most of their internal organs (of which they have rather few; respiration is done across the body surface, so no gills) into the legs.

The more I look at them, the funnier they look – but that may be in the eye of the beholder, as a few arachnophobes passing by the camera have declared loudly that there is nothing charming to find here – I beg to disagree!

Goofy looking Nymphon stroemi (note the cheliphores/claws)

Goofy looking Nymphon stroemi (note the chelipores/claws) and the eyes on a tubercle on the head – they have eyes facing both forwards and backwards

Pycnogonum litorale

Pycnogonum litorale

Some species, like this Nymphon gracile, can also swim: "...the swimming motions are the same as those used in walking, but more vigorously executed" King 1974

Some species, like this Nymphon gracile, can also swim: “…the swimming motions are the same as those used in walking, but more vigorously executed” King 1974

Nymphon hirtipes with hitchikers

Nymphon hirtipes with hitchikers

ZMBN_104970

Pseudopallene circularis from Spitsbergen

They are usually slow movers: Hover over the image to see a pycnogonid walking on the sea floor

To fill a plate with tissue samples from 95 specimens (1 animal = 1 specimen) of pycnogonida doesn’t sound too complicated, does it? Well, it turned out to be a bit of an adventure to gather enough animals that had been preserved in such a way that we could get DNA out of them (older material is usually fixated in Formaldehyde, which makes it unsuited for genetic work), and that was identified (had a name to them). Since we are in the process of building up the national (and international) reference library (the BOLD database) that the short DNA-segments (the “barcodes”) are to be matched up to later when someone wants to know which species “Animal X” belongs to, we need to know which species we are submitting for sequencing.

Our collection of barcode-compatible identified pycnogonids received a welcome boost when the shipment of processed material (identified, and measured for biomass) from MAREANO‘s beamtrals collected in 2013 arrived, as these had been fixated in ethanol – and identified by researchers who have worked extensively with the group.

Even so, I couldn’t fill a whole plate with only those specimens. Thankfully, I have skilled collegues that were able to put species names to almost all of the critters I could hunt down in our collections, and so now we have 95 animals ready from 26 different species! We also have some bona fide mysteries that we hope the BOLD-database will help us solve as well; animals that does not comply with any of the identification keys…!

Fingers crossed for a very successful sequence run and a lot of new information about  the Pycnogonida of Norway!

Pseudopallene longicollis, collected by MAREANO

Pseudopallene longicollis, collected by MAREANO

Info:
King, P.E. 1974: British Sea Spiders, synopses of the British Fauna (New Series) No. 5

Door #3: a week in the field

We spent a lovely week in October collecting animals at the field station of NTNU in Agdenes in central Norway.

About 15 researchers and collection curators were gathered for a week of sampling with gear ranging from grabs and trawls deployed from the research vessel Gunnerus to buckets and shovels on the beach. As you may be able to tell, a good time was had by all!

Sletvik_collage

The field work was arranged by the our colleagues at NTNU University Museum, and served multiple purposes:

  • We collected ultra-fresh material for barcoding through the norwegian Barcode of Live project (NorBOL) – several plates were initiated during the week and then brought back to Bergen where we will continue filling them with material from our collections – each plate needs to be filled with 95 samples that can be run with the same primer, so we need to select our material carefully.
  • The marine collections of NTNU got a substantial boost
  • Fresh material was collected for teaching faunistics
  • Photodocumenting live specimens (we have some fantastic polychaete photos from this coming up later in our calendar)
  • Four Norwegian Species Initiative funded projects were participating, collecting material for their projects – as were people from the EU-project SponGES.
  • We at UM also relished the chance to sample in the littoral zone, which is a undersampled habitat in our collections

We are working on the material now, and some of it is scheduled to make an apperance on the blog over the next couple of weeks – so stay tuned!

Door #2: The head of the Medusa

Medusa_by_Carvaggio

Medusa by Carvaggio (Wikimedia)

Today we go mythological, and visit the Greek pantheon.

Medusa was one of three Gorgon sisters who all had snakes for hair according to the mythology – and one can certainly understand how the British zoologist Leach (1791-1836) came to think of the name when he formally described the genus Gorgonocephalus (Literally ” Gorgon’s head”) in 1815. They are found within the echinoderm class of Ophiuroidea (brittle stars).

In English they are known as basket stars, whilst Norwegians know them as “Medusahode” – head of the Medusa.

The English name refers to how they feed: basket stars are predators, and raise their bifurcated arms covered with tiny hooks, spines and grooves up into the current forming a basket to sift and entrap plankton and other small critters from the water as it streams past – then they use their arm branches (possibly aided by the tube feet) to guide the trapped food to their mouths, which is on the underside (like in starfish).

Gorgonocephalus lamarcki, photo by K.Kongshavn

Gorgonocephalus lamarcki, photo by K.Kongshavn

kart

This specimen was collected in Svalbard in 2009 (way up at 80ºN) during a student course at UNIS, and has been barcoded through the Norwegian Barcode of Life (NorBOL) project.

 

Hover your cursor over the image below to see a basket star move

-Katrine

Door #1 Gammarus wilkitzkii – closer than Santa to the North Pole?

We greet December with our 2016 edition of the invertebrate advent calendar, and will be posting a new blog post here every day from today until the 24th of December! Be sure to check in often! All posts of this year’s calendar will be collected here: 2016 calendar, and all of the post in last year’s event are gathered here in case you would like a recap: 2015 edition. First out is Anne Helene and a Northern amphipod:

December is over us, the Advent Calendar from the invertebrate section lets you open the first door today, and many children (both small and slightly older) are eagerly awaiting the answer to their letter to Santa Claus. Mr Claus is supposed to live on the North Pole, and many letters addressed there have been coming through different post-offices the last months.

Many of us are wondering if Santa Claus might be a Species dubius (a species it is slightly doubtful exists), but if he exists, his homestead is becoming endangered. We are seeing a rapid decline of the Arctic sea ice (here is a video from NOAA showing the extent and age of the icecap from 1987 to 2014), and this will undoubtedly have a large effect on the Earths climate.

A polar bear mother and cub walking on the top of the sea ice. Photo: AHS Tandberg

A polar bear mother and cub walking on the top of the sea ice. Photo: AHS Tandberg

In addition to the theoretical possibility of Santa, there are several true and precious species that depend on the sea ice for their life. Most probably think about polar bears and seals now, but there is an even more teeming abundance of life right under the ice, many of them live as the sea ice is an upside-down seafloor. The largest animal biomass of all the many invertebrate species connected to the sea ice (we call these sympagic species), comes form the amphipod Gammarus wilkitzkii Birula 1897.

Gammarus wilkitzkii is the largest of the invertebrates that hang out (literally) under the ice; they can reach almost 3 cm length. They are whitish-grey, with red-striped, long legs. The hind legs have hooks that allow them to easily attach to the sea ice, and hanging directly under the ice instead of swimming saves a lot of energy for them. This behaviour is so necessary to them that if we keep them in an aquarium, they need something to hang on to – be it the oxygen-pump, a piece of styrofoam, the hand of a researcher or the edge of the lid. There are a few observations of swimming G. wilkitzkii sampled from the middle of the water-column, but this seems to be specimens that have lost their hold in life – we do not think they can live long swimming around (that would take too much energy).

A male (white) Gammarus wilkitzkii holding a female (yellow) Gammarus wilkitzkii. The male is also holding on to the sea-ice with his hind legs. Photo: Bjørn Gulliksen, University of Tromsø and UNIS.

A male (white) Gammarus wilkitzkii holding a female (yellow) Gammarus wilkitzkii. The male is also holding on to the sea-ice with his hind legs. Photo: Bjørn Gulliksen, University of Tromsø and UNIS.

Being such large animals, and in such large abundance, G. wilkitzkii are preyed upon mostly by diving sea-birds, but they have also been found in the stomach-content of harp-seals and to a small degree the small and stealthy polar cod. Most of these animals are mainly found in what we call the marginal ice zone – where the sea ice meets the open water. This is also the place where G. wilkitzkii can find most of its own food: algae, other small invertebrates and ice-bound detritus.

A diver under the sea ice. Photo: Geir Johnsen, NTNU

A diver under the sea ice. Photo: Geir Johnsen, NTNU

G. wilkitzkii is also found in great quantities under the multi-year ice, where it probably leads a safer life. Being at the edge of the ice presents a problem: this is the ice that melts during the summer, and that will force the amphipods to move further into the ice as its habitats disappear. The underside of the ice is not a flat field – it is a labyrinth of upside-down mountains and valleys, with several small and large caves. Many nice hiding-places, but if you swim or crawl along the ice-surface, the distance is longer than we would measure it on the top of the ice.

Where the ice is thin, or where there is no snow covering the ice, some light will shine through. This means that the edge of the ice normally lets a lot more light through than the multi-year ice. We dont know what this does for G. wilkitzkii, but they have eyes that are of similar size and shape as the other species in the genus, so they possibly use their eyes for hunting for food or checking for enemies.


G. wilkitzkii is an animal that is accustomed to a tough life. The sea temperature right under the ice normally lies around -1.8ºC, (so below what we think of as “freezing”) this is because of the high salinity of the water. As sea-water freezes, the salt leaks out, and flows in tiny brine-rivers trough the ice and down into the water below.  They have specialised their life cycle to fit with the available food – so that their young are released when there is much food to be found, and they can live up to 6 years reproducing once every of the last 5 years, probably to make sure at least some of their offspring survive.

We have 24 more days before we find out if Santa “exists”, though this might not give us the answer to him having become a climate-refugee. Hopefully, we will have to wait much longer to find out what will happen with the many ice-dependent invertebrates, but becoming climate-refugees might not be easily accomplished for them.

Anne Helene


Literature:

Arndt C, Lønne OJ (2002) Transport of bioenergy by large scale arctic ice drift. Ice in the environment – Proceedings of the 16th IAHR International Symposium on Ice, Dunedin , NZ. p103-111.

Gulliksen B, Lønne OJ (1991) Sea ice macrofauna in the antarctic and the Arctic. Journal of Marine Systems 2, 53-61.

Lønne OJ, Gulliksen B (1991) Sympagic macro-fauna from multiyear sea-ice near Svalbard. Polar Biology 11, 471-477.

Werner I, Auel H, Garrity C, Hagen W (1999) Pelagic occurence of the sympagic amphipod Gammarus wilkitzkii in ice-free waters of the Greenland Sea – dead end or part of life-cycle? Polar Biology 22, 55-60.

Weslawski JM, Legezinska J (2002) Life cycles of some Arctic amphipods. Polish Polar Resarch 23, 2-53.

’tis (soon) the season..

..for our December marine invertebrates calendar countdown!

Last year we made a blog post every day for December 1-24th.

We covered all sorts of topics, below are some of the illustrations. Check out all the 2015 calendar posts here.

Snapshots from the 2015 edition

Snapshots from the 2015 edition

We’re planning the 2016 edition now, and hope to come up with 24 fun/interesting/educational/cool posts – check back in a week’s time to see how it goes!