Unraveling copepod secrets and techniques one leg at a time

A weblog by HYPCOP

Hyperbenthic copepods (HYPCOP) are a really troublesome and numerous group to work with, and identification goes painstakingly sluggish, 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’ve no specialists in marine benthic copepods in Norway and our biggest useful resource is our collaborator Anders Hobæk and the detailed drawings of G.O. Sars from the early 1900s .

Working collectively underneath steerage 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, nonetheless, 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 via the principle clades and teams of species that we had DNA barcodes of however not but a confirmed species identify. Plenty of the identification was achieved 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 quite a lot 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, develop into of uttermost significance in figuring out the species. With small copepods you want a very good microscope and nice instruments. The very first thing to take a look at is the final 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 appropriate 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 giant, small, nearly 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, is usually a big as compared of the remainder of its physique.

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

Our work has a continues workflow consisting of, gathering the copepods, extracting their tissue for DNA barcoding, and holding 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 method the copepod is recognized based mostly on its DNA and morphological options, as this isn’t all the time mutually unique. DNA might be tough as you want a very good reference library to search out the right 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 have a look at the morphology to exclude that the DNA provides you the incorrect species. Along with pictures of the animals we’re build up a invaluable reference library of DNA sequences and a museum assortment of dissected animals on fastened slides. This manner copepod variety will proceed to be invaluable for future generations high research.

Working underneath 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