Unraveling copepod secrets and techniques one leg at a time

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A weblog by HYPCOP

Hyperbenthic copepods (HYPCOP) are a really troublesome and various group to work with, and identification goes painstakingly gradual, as a result of some species can solely be distinguished from each other based mostly on small particulars in a few of their tiny legs. As of now, we now have no specialists in marine benthic copepods in Norway and our best useful resource is our collaborator Anders Hobæk and the detailed drawings of G.O. Sars from the early 1900s .

Working collectively below steering of G.O. Sars and Anders Hobæk

Anders is a senior researcher scientist on the Norwegian Institute for Water Analysis (NIVA) right here in Bergen. He’s specialised in copepod taxonomy, however his focus was totally on freshwater copepods, or marine pelagic copepods. Which makes the marine benthic copepods just a bit bit more difficult to work with, nevertheless, his expertise are transferable and so we get collectively a number of occasions a 12 months to work on our assortment of benthic copepods to dissect them and determine them.

Starting of June, we had once more a type of get togethers in Flødevigen on the Institute of Marine Analysis (IMR), the place Tone Falkenhaug, the undertaking chief of HYPCOP, is located. For every week we went by means of the primary clades and teams of species that we had DNA barcodes of however not but a confirmed species title. A number of the identification was executed with assist of the wealthy and detailed illustrations of G.O. Sars1 revealed work in 1901 – 03 and 1919 – 21, “An account of Crustacea of Norway”

Detailed copepod drawings from G.O. Sars

Sars devoted a lifetime of figuring out and describing a wide range of species and he didn’t neglect the wealthy and fantastic group of backside dwelling copepods. Each species he encountered in these early days he described and drew intimately; he didn’t omit the smallest particulars, that as of now, turn into of uttermost significance in figuring out the species. With small copepods you want a great microscope and wonderful instruments. The very first thing to take a look at is the overall form, is it very dorsally flat, like Peltidium purpureum, or extra dimensional like Harpacticus flexus?

Intercourse can be an essential function; females are sometimes characterised by carrying eggs; one egg sack or two egg sacks can already lead you in the correct group. Males have typically bigger antennule made for holding on to females when mating, and different specialised instruments that may be species particular. The little claws, known as maxilliped, are they massive, small, virtually invisible? What concerning the first pair of legs? The second, third and fourth? The fifth pair of legs is usually very attribute for the species and in sure females, like Thalestris longimana, generally is a enormous compared of the remainder of its physique.

Thalestris longimana, females of this species has comparatively massive fifth pair of legs

Our work has a continues workflow consisting of, gathering the copepods, extracting their tissue for DNA barcoding, and retaining the exoskeleton. As soon as the DNA is efficiently sequenced, we are able to take the exoskeleton and dissect the animal leg by leg to finalize the identification. That manner the copepod is recognized based mostly on its DNA and morphological options, as this isn’t at all times mutually unique. DNA will be difficult as you want a great reference library to seek out the right species, which is as of now, not full, and even missing for a lot of species. In addition to, there’s things like DNA contamination, cross contamination between species, due to this fact you at all times should have a look at the morphology to exclude that the DNA offers you the improper species. Along with photos of the animals we’re increase a useful reference library of DNA sequences and a museum assortment of dissected animals on mounted slides. This fashion copepod variety will proceed to be useful for future generations high research.

Working below the eyes of G.O. Sars

-Cessa


1Sars, G. O. 1901-03. An Account of the Crustacea of Norway. Vol. IV. Copepoda Calanoida.- Bergen Museum, Bergen & Christiana. 171 pp. + 109 plates Sars, G. O. 1919-21. An Account of the Crustacea of Norway. Vol. VII. Copepoda. Complement. – Bergen Museum, Bergen & Christiana. 121 pp. + 74 plates

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