Unraveling copepod secrets and techniques one leg at a time

A weblog by HYPCOP

Hyperbenthic copepods (HYPCOP) are a really tough and various group to work with, and identification goes painstakingly gradual, as a result of some species can solely be distinguished from each other primarily based on small particulars in a few of their tiny legs. As of now, we’ve 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 .

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 abilities 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 mission chief of HYPCOP, is located. For every week we went by the principle clades and teams of species that we had DNA barcodes of however not but a confirmed species title. Plenty of the identification was carried out 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”

Sars devoted a lifetime of figuring out and describing quite a lot of species and he didn’t neglect the wealthy and great group of backside dwelling copepods. Each species he encountered in these early days he described and drew intimately; he didn’t pass over the smallest particulars, that as of now, grow to be of uttermost significance in figuring out the species. With small copepods you want an excellent microscope and tremendous instruments. The very first thing to have a look at is the overall form, is it very dorsally flat, like Peltidium purpureum, or extra dimensional like Harpacticus flexus?

Intercourse can also be an essential function; females are sometimes characterised by carrying eggs; one egg sack or two egg sacks can already lead you in the best group. Males have usually bigger antennule made for holding on to females when mating, and different specialised instruments that may be species particular. The little claws, referred to 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 commonly very attribute for the species and in sure females, like Thalestris longimana, is usually a big compared of the remainder of its physique.

Our work has a continues workflow consisting of, gathering the copepods, extracting their tissue for DNA barcoding, and protecting 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 approach the copepod is recognized primarily based on its DNA and morphological options, as this isn’t all the time mutually unique. DNA could be difficult as you want an excellent reference library to search out the proper species, which is as of now, not full, and even missing for a lot of species. Apart from, there may be things like DNA contamination, cross contamination between species, subsequently you all the time should take a look at the morphology to exclude that the DNA offers you the mistaken species. Along with photographs of the animals we’re build up a priceless reference library of DNA sequences and a museum assortment of dissected animals on fastened slides. This manner copepod range will proceed to be priceless for future generations prime examine.

-Cessa

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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