Unraveling copepod secrets and techniques one leg at a time

A weblog by HYPCOP

Hyperbenthic copepods (HYPCOP) are a really troublesome and various 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 .

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 abilities are transferable and so we get collectively a number of occasions a yr to work on our assortment of benthic copepods to dissect them and establish them.

Starting of June, we had once more a kind of get togethers in Flødevigen on the Institute of Marine Analysis (IMR), the place Tone Falkenhaug, the undertaking chief of HYPCOP, is located. For per week we went by way of the primary clades and teams of species that we had DNA barcodes of however not but a confirmed species identify. A variety of the identification was performed 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 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 a superb microscope and tremendous instruments. The very first thing to have a look at is the final form, is it very dorsally flat, like Peltidium purpureum, or extra dimensional like Harpacticus flexus?

Intercourse can also be an vital characteristic; females are sometimes characterised by carrying eggs; one egg sack or two egg sacks can already lead you in the fitting 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, known as maxilliped, are they giant, small, virtually invisible? What in regards to 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 enormous 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, amassing the copepods, extracting their tissue for DNA barcoding, and maintaining the exoskeleton. As soon as the DNA is efficiently sequenced, we will take the exoskeleton and dissect the animal leg by leg to finalize the identification. That means 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 superb reference library to search out the proper species, which is as of now, not full, and even missing for a lot of species. In addition to, there may be things like DNA contamination, cross contamination between species, due to this fact you all the time should take a look at the morphology to exclude that the DNA provides you the improper species. Along with photos of the animals we’re build up a invaluable reference library of DNA sequences and a museum assortment of dissected animals on mounted slides. This fashion copepod range will proceed to be invaluable for future generations high research.

Working beneath 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