Monthly Archives: December 2015

Door #4: A cushioned star

This gorgeous sea star was first described by O.F. Müller in 1776. He gave it a species name fitting the characteristic appearance of the animal (Lat. Pulvillus= pillow, cushion). The common names in both English – Red Cushion Star- and Norwegian – Sypute – also reflect on this. Though most commonly red like the specimen pictured below, they can also be yellow-white. The white protrusions on the upper side the are gills. It lives at 10-300 meters depth, where it is often seen feeding on the coral Alcyonium digitatum. This particular specimen was collected during the course in marine faunistics this fall, in a locality just outside our field station close to Bergen.

Strangely enough, considering how common, conspicuous and wide-spread the species is, it has not been barcoded very frequently in BOLD – our specimen here will be the fifth in total to be submitted..!

Screen shot from a search in BOLD for the species

Screen shot from a search in BOLD for Porania pulvillus

-Katrine

Door #3: Prepare to be HYPNOtized

One of this year’s new projects at the Invertebrate collections is HYPNO – Hydrozoan pelagic diversity in Norway, funded by the Norwegian Taxonomy Initiative.

A selection of photos depicting some of the species encountered so far in the project

Hydrozoa are a class of cnidarians, the pelagic representatives of which include hydromedusae as well as colonial siphonophores and porpitids. They are thus “cousins” to the more familiar larger scyphozoan jellyfish such as the moon jelly or the lion’s mane jelly. The size of pelagic hydrozoans ranges from small medusae of less than 1 mm to siphonophore colonies reaching several meters in length. They are mostly predators that use their tentacles and stinging cells to catch other zooplankton or even fish larvae. Most of the time they go largely unnoticed by the public, but at times they can form blooms and deplete zooplankton as well as cause problems for aquaculture and fisheries or sting bathers.

The aim of HYPNO is to chart, document and DNA-barcode the diversity of hydromedusae and siphonophores occurring in Norway. Gelatinous zooplankton, including hydrozoans, has been generally less studied than their crustacean counterparts, and we know less about their diversity. This is due to several challenges in studying them. First of all, many pelagic hydrozoans, particularly the colonial siphonophores, are very fragile and often damaged during sampling with standard plankton nets. This can make it difficult to identify them. Secondly, preserving hydromedusae and siphonophores for later work is problematic. For morphological studies, they are best preserved in formalin, since most other fixatives used for zooplankton -including ethanol- cause distortion and shrinkage of their gelatinous bodies, rendering the animals impossible to identify. Formalin fixation, however, hinders further genetic work.

To overcome these practical problems, HYPNO uses gentle collection methods to obtain specimens in good condition. Collected samples are immediately examined for hydrozoans, and the live animals are identified and documented with photos before they are fixed in ethanol for DNA barcoding of CO1 and 16S sequences.

So far, HYPNO has participated on two cruises by the Institute of Marine Research: to the North Sea and Skagerrak on RV Johan Hjort 24 Apr – 4 May 2015 and to the Arctic Ocean and Fram Strait on RV Helmer Hanssen 17 Aug – 7 Sep 2015. So far, 34 species have been photographed and sampled for DNA. Here is a selection of pictures depicting some of the species encountered during these surveys.

You can read more about HYPNO at http://data.artsdatabanken.no/Pages/168312.

-Aino

Door #2: The Leaf Sheep Sea Slug

Costasiella (Pruvot-Fol, 1951) or Leaf Sheep Sea Slugs recently gained a lot of attention online, due to many of the species resembling cute green cartoon sheep, but there is much more to them than just their cute appearances.

Regular sheep vs Leaf Sheep Sea Slugs (ill: T.R. Oskars)

Within Heterobranchia (sea slugs and land snails) they fall within the Saccoglossa, or sap sucking sea slugs, which feed by sucking out the cell contents of algae. Some of the species within this group simply digest the entire cell straight away, whereas some have the unique ability to retain some of the cellular components from the algae in a functional state within their body, a process called kleptoplasty (plastid stealing).

Costasiella is one of these plastid thieves, who retain the chloroplasts of the algae and can use them to fix carbon trough photosynthesis, an ability that is unique for saccoglossans amongst animals, leading to the often being referred to as “crawling leafs”. The plastids can aid the slug to survive for extended periods without food, and even if the slugs are thought to benefit from the products of the plastids, in dark conditions they also seems to work just as well as emergency rations, making even the main role of the plastids questionable. In addition precisely how these slugs can retain the functional chloroplasts in their body is still unknown; however the leading theory was for a long time that Costasiella also stole genes for managing the plastids from the cell nucleus of the algae (horizontal gene transfer). Such genes have however not yet been found in the genome of Costasiella, but has been found in its saccoglossan cousin Elysia chlorotica who can in addition pass these genes on to their offspring. The chloroplasts are however not inherited by the next generation of Costasiella or E. chlorotica, so the young have to go out and find their own before they can be true “crawling leafs”. In addition to being cute ambassadors of slimy slugs, Costasiella is also a little mystery.

Suggested reading:

Christa, G., Gould, S. B., Franken, J., Vleugels, M., Karmeinski, D., Händeler, K., … & Wägele, H. (2014). Functional kleptoplasty in a limapontioidean genus: phylogeny, food preferences and photosynthesis in Costasiella, with a focus on C. ocellifera (Gastropoda: Sacoglossa). Journal of Molluscan Studies, 80(5), 499-507.

Christa, G., de Vries, J., Jahns, P., & Gould, S. B. (2014). Switching off photosynthesis: the dark side of sacoglossan slugs. Communicative & integrative biology, 7(1), 20132493-3.

Schwartz, J. A., Curtis, N. E., & Pierce, S. K. (2014). FISH labeling reveals a horizontally transferred algal (Vaucheria litorea) nuclear gene on a sea slug (Elysia chlorotica) chromosome. The Biological Bulletin, 227(3), 300-312.

de Vries, J., Christa, G., & Gould, S. B. (2014). Plastid survival in the cytosol of animal cells. Trends in plant science, 19(6), 347-350.

de Vries, J., Rauch, C., Christa, G., & Gould, S. B. (2014). A sea slug’s guide to plastid symbiosis. Acta Societatis Botanicorum Poloniae, 83(4)

-Trond

Door #1: A day at sea

Welcome to our marine invertebrates December calendar! In Norway it is very common for children to have a Advent calendar of some sort to help shorten the wait towards Christmas.

We’ve decided to run with the idea here on the blog, giving you a tidbit about our work every day from December 1st to 24th.

We hope you’ll join us on our little venture – we can guarantee a varied selection of topics!

All the posts will be gathered under the Category 2015 December calendar

First out is a tale of sampling in the sleet…!

The scientific collections are the backbone of all the research performed at the University Museum – as it is at any museum. They hold treasures collected through the entire lifetime of a museum, and most times a collection was the reason for the establishment of a proper museum. The University Museum of Bergen is one of the oldest natural history collections in Norway, and we have grand collections.

But a collection needs to live – to be added to and to be used of – and this was the reason that bright and early Monday morning Katrine and Anne Helene were ready to go to sea. Our goal was to make a jumpstart at Anne Helenes new project about Amphipods (more about that in a later blog), and to take a grab (or two) of sandy seafloor to look for bristle worms (Polychaeta).

It is always a risk planning on a cruise in the very end of November, but this time the weather was on our side. Our plan – “go out and grab animals, sandy bottom is nice” – was cooked up in the spur of the moment when we got an offer for boat time late Friday afternoon (someone else had to change their plans in the last minute), and maybe that was why everything went so smoothly? Going out collecting benthic animals (those that live on the seafloor) is one of our favourite things, and so we didn’t need much prodding.

The grab and sledge performed beautifully, and now is the time for sorting and photographing live animals before adding them to the collection. Be sure to follow their story through later blogs – they will show up in the categories NorAmph and NorBOL, and maybe somewhere else as well?