Northern krill: Difference between revisions

Revision as of 23:28, 14 July 2005

Latest revision as of 20:31, 23 July 2025

(76 intermediate revisions by 52 users not shown)

Line 1:

{{Short description|Species of krill}}

{{Taxobox_begin | color = pink | name = Northern krill}}

{{Speciesbox

{{Taxobox_image | image = [[Image:Meganyctiphanes norvegica.jpg|250px]] | caption =}}

{{Taxobox_begin | color = pink | name = Northern krill}}

{{Taxobox_begin_placement | color = pink}}

{{Taxobox_image | image = [[Image:Meganyctiphanes norvegica.jpg|250px]] | caption =}}

{{Taxobox_regnum_entry | taxon = [[Animal]]ia}}

| genus = Meganyctiphanes

{{Taxobox_phylum_entry | taxon = [[Arthropod]]a}}

| parent_authority = [[Ernest William Lyons Holt|Holt]] & [[Walter Medley Tattersall|Tattersall]], 1905

{{Taxobox_subphylum_entry | taxon = [[Crustacea]]}}

| species = norvegica

{{Taxobox_classis_entry | taxon = [[Malacostraca]]}}

| authority = ([[Michael Sars|M. Sars]], 1857)

{{Taxobox_ordo_entry | taxon = [[Euphausiacea]]}}

| synonyms = *''Euphausia intermedia''

{{Taxobox_familia_entry | taxon = [[Euphausiidae]]}}

*''Euphausia lanei'' <small>Holt & Tattersall, 1905</small>

{{Taxobox_genus_entry | taxon = '''''Meganyctiphanes'''''}}

[[de:*''Meganyctiphanes norvegica]]calmani''

{{Taxobox_authority | author = [[Holt (taxonomy)|Holt]] and [[Tattersall (taxonomy)|W. M. Tattersall]] | date = [[1905]]}}

*''Nyctiphanes norvegicus'' <small>G. O. Sars, 1883</small>

{{Taxobox_species_entry | taxon = '''''norvegica'''''}}

*''Thysanopoda norvegica''

{{Taxobox_end_placement}}

}}

{{Taxobox_section_binomial | color = pink | binomial_name = Meganyctiphanes norvegica | author = ([[Michael Sars|M. Sars]] | date = [[1856]])}}

{{Taxobox_end}}

'''Northern krill''' (''Meganyctiphanes norvegica'') is a [[crustaceanspecies]] of [[krill]] that lives in the [[North Atlantic Ocean]]. Itincluding isthe part[[Norwegian of theSea]], [[zooplanktonNorth Sea]]., Itand isparts anof the [[euphausiidMediterranean Sea|Mediterranean]]. andIt ais veryan important component of the [[planktonzooplankton]], of the ocean,providing food for [[whale]]s, [[fishPinniped|seals]] and, [[birdfish]]s. The gut is shining through in red, an indication that this species feeds predominantly onand [[copepodbird]]s. In the [[Southern Ocean]], the [[Antarctic krill]] ''[[Euphausia superba]]'' fills a similar role. ''M. norvegica'' is the only species recognized in the genus ''Meganyctiphanes''.<ref>{{Cite web |title=WoRMS - World Register of Marine Species - Meganyctiphanes Holt & Tattersall, 1905 |url=https://www.marinespecies.org/aphia.php?p=taxdetails&id=110674 |access-date=2025-02-17 |website=www.marinespecies.org}}</ref>

Northern krill supply a crucial link in the [[North Atlantic Ocean]] [[food web]], transmitting energy from [[primary producers]] to high-level predators. Krill in the North Atlantic Oceans feed on [[phytoplankton]], [[copepod]]s, and other [[zooplankton]].<ref>{{Cite web |title=Creature Feature: Krill |url=https://twilightzone.whoi.edu/explore-the-otz/creature-features/krill/#:~:text=Most%20krill%20are%20filter%20feeders,like%20zooplankton%20and%20fish%20larvae. |access-date=2025-02-18 |website=twilightzone.whoi.edu/ |language=en-US}}</ref>

The Northern krill is the only species of the genus ''Meganyctiphanes''.

== ExternalAnatomy linksand morphology ==

=== External morphology ===

* [http://www.itis.usda.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=95533 Taxonomy of ''Meganyctiphanes norvegica''] from [[ITIS]].

[[File:Meganyctiphanes_norvegica_162191972.png|thumb|Cephalothorax of a Northern Krill showing its [[compound eye]]s and two [[Antenna (zoology)|antenna]]]]

* [http://www.ecoscope.com/meganyct.htm Northern krill - Meganyctiphanes norvegica].

[[File:Meganyctiphanes_norvegica_162191940.png|thumb|Small but powerful tail fin and transparent [[chitin]]ous [[exoskeleton]].]]

Similar to all krill species, northern krill are [[crustacean]]s that possess a transparent [[chitin]]ous [[exoskeleton]]. Northern krill can grow up to 4-6 centimeters long in adult hood, although on average they are 1.5–2 centimeters.<ref>{{Cite journal |last1=Silva |first1=Teresa |last2=Gislason |first2=Astthor |last3=Astthorsson |first3=Olafur S. |last4=Marteinsdóttir |first4=Gudrún |date=2017 |title=Distribution, maturity and population structure of Meganyctiphanes norvegica and Thysanoessa inermis around Iceland in spring |journal=PLOS ONE |volume=12 |issue=11 |pages=e0187360 |doi=10.1371/journal.pone.0187360 |doi-access=free |issn=1932-6203 |pmc=5675434 |pmid=29112989|bibcode=2017PLoSO..1287360S }}</ref> Their anatomy is a [[decapod]] consisting of three main sections: the cephalothorax, the abdomen, and the tail fan. The cephalothorax is the krill's [[head]] which houses two [[Antenna (zoology)|antenna]] and [[compound eye]]s. Northern krill utilize their antenna to sense their surroundings and aiding in eating feed. In addition to the northern krill's antenna they also have [[maxillipeds]] which aid them in handling food to their [[mandible]].<ref name=":0">{{Citation |last=Schmidt |first=Katrin |title=Food and Feeding in Northern Krill (Meganyctiphanes norvegica Sars) |date=2010-01-01 |series=Advances in Marine Biology |volume=57 |pages=127–171 |editor-last=Tarling |editor-first=Geraint A. |url=https://www.sciencedirect.com/science/article/abs/pii/B9780123813084000054 |access-date=2025-03-02 |publisher=Academic Press|doi=10.1016/B978-0-12-381308-4.00005-4 |pmid=20955891 |isbn=978-0-12-381308-4 |url-access=subscription }}</ref> Found in insects, krill also operate through compound eyes which allows them to see a large array of area, detect rapid movement, and see in deep sea light conditions.<ref>{{Cite book |last1=Tarling |first1=Geraint A. |last2=Ensor |first2=Natalie S. |last3=Fregin |first3=Torsten |last4=Goodall-Copestake |first4=William P. |last5=Fretwell |first5=Peter |title=An Introduction to the Biology of Northern Krill (Meganyctiphanes norvegica Sars) |series=Advances in Marine Biology |date=2010 |volume=57 |pages=1–40 |doi=10.1016/B978-0-12-381308-4.00001-7 |issn=0065-2881 |pmid=20955887|isbn=978-0-12-381308-4 }}</ref> Northern krill also possess [[mandible]]s and [[maxillipeds]] which aid them in eating

Attached to the cephalothorax is the [[abdomen]] which contains ten [[appendage]]s to aid with swimming. These appendages are five pairs of forked non walking legs referred to as [[pleopods]] or "[[swimmerets]]". Unique to a standard decapod krill use their pleopods for more than just swimming incorporating them into how they groom and eat. Their tail fan assists the northern krill to propel forward when swimming.<ref>{{Cite book |last=Fregin |first=Torsten |title=An Introduction to the Biology of Northern Krill (Meganyctiphanes norvegica Sars) |date=2010-01-01 |url=https://www.academia.edu/10765201 |series=Advances in Marine Biology |volume=57 |pages=1–40 |doi=10.1016/B978-0-12-381308-4.00001-7 |pmid=20955887 |isbn=978-0-12-381308-4 }}</ref>

=== Internal Anatomy ===

{{invertebrate-stub}}

Northern krill are adapted for survival in the [[pelagic zone]] of the ocean, enabling them to feed, escape predators, and reproduce.<ref>{{Cite web |last=University |first=Uppsala |title=Krill provide insights into how marine species can adapt to warmer waters |url=https://phys.org/news/2024-08-krill-insights-marine-species-warmer.html |access-date=2025-03-02 |website=phys.org |language=en}}</ref>

==== Digestive System ====

[[Category:Krill]]

The northern krill's digestive system starts at their [[maxillipeds]] which files food into their mouths which leads to the [[esophagus]]. The [[esophagus]] is connected to their stomach which consists of a cardiac stomach and a [[pyloric stomach]]. Their cardiac stomach is the initial part of the stomach which helps grind the krill's food. The pyloric stomach is located in the lower stomach region which directs movement of their food into the [[small intestine]]. The northern krill's pyloric stomach allows any bacteria to be passed right through the stomach due to the fast turnover rate.<ref name=":0" /> The food moves through the [[intestines]] located through the abdomen, leading to the [[anus]] to discrete the food particles.

==== Circulatory System ====

[[da:Meganyctiphanes_norvegica]]

The northern krill's [[circulatory system]] is open. An [[open circulatory system]] is where the krill's form of blood [[hemolymph]] soaks the organs directly. The [[tissue fluid]] is mixed with the [[hemolymph]]. Northern krill have a small [[heart]] located on the back or [[dorsal side]]. This dorsal heart pumps the blood through the krill's [[arteries]].<ref>{{Cite journal |last1=Benkort |first1=Déborah |last2=Lavoie |first2=Diane |last3=Plourde |first3=Stéphane |last4=Dufresne |first4=Christiane |last5=Maps |first5=Frédéric |date=2020-03-01 |title=Arctic and Nordic krill circuits of production revealed by the interactions between their physiology, swimming behaviour and circulation |url=https://www.sciencedirect.com/science/article/abs/pii/S0079661120300082 |journal=Progress in Oceanography |volume=182 |article-number=102270 |doi=10.1016/j.pocean.2020.102270 |bibcode=2020PrOce.18202270B |issn=0079-6611|url-access=subscription }}</ref>

[[de:Meganyctiphanes norvegica]]

==== Respiratory System ====

Northern krill do not breathe [[oxygen]] from the atmosphere they breathe oxygen present in water. Krill use their [[gill]]s located on their [[pleopod]] appendages attached to their abdomen to exhale and respire. Once krill breathe in the oxygen can be seen circulating throughout their body via [[respiratory pigment]]. Respiratory pigment is the term used when referring to a protein that transports oxygen into the blood and tissues.<ref>{{Cite web |title=Respiratory pigment {{!}} biochemistry {{!}} Britannica |url=https://www.britannica.com/science/respiratory-pigment |access-date=2025-03-03 |website=www.britannica.com |language=en}}</ref> In northern krill, the respiratory pigment is called [[hemocyanin]].<ref>{{Cite web |title=Hemocyanin {{!}} biochemistry {{!}} Britannica |url=https://www.britannica.com/science/hemocyanin |access-date=2025-03-03 |website=www.britannica.com |language=en}}</ref> Unlike [[hemoglobin]], hemocyanin is susceptible to change due to temperature and has a weak affinity for oxygen. Due to their low affinity for oxygen, krill's [[respiration rate]] changes in response to temperature changes. This makes northern krill more susceptible to death with fluctuations in temperature and [[Oxygenation Crisis|oxygenation]] levels.<ref>{{Cite journal |last1=Michael |first1=Katharina |last2=Suberg |first2=Lavinia A. |last3=Wessels |first3=Wiebke |last4=Kawaguchi |first4=So |last5=Meyer |first5=Bettina |date=2021-06-01 |title=Facing Southern Ocean warming: Temperature effects on whole animal performance of Antarctic krill (Euphausia superba) |url=https://www.sciencedirect.com/science/article/abs/pii/S0944200621000180 |journal=Zoology |volume=146 |article-number=125910 |doi=10.1016/j.zool.2021.125910 |pmid=33735797 |bibcode=2021Zool..14625910M |issn=0944-2006}}</ref>

==== Photophores ====

Not only do northern krill possess a transparent chitinous exoskeleton, but they also have bioluminescent organs. Found in many fish these bioluminescent organs otherwise known as [[photophore]]s are hypothesized to help the krill camouflage and communicate. Photophores are organs that emit light. On krill, they are located on the [[eyestalk]]s, ventral thorax, and abdomen. They are often attributed to aiding in luring prey and [[male intrasexual competition]]. Their transparent body and bioluminescent organs help northern krill evade predators.<ref name="Krieger 101393">{{Cite journal |last1=Krieger |first1=Jakob |last2=Fregin |first2=Torsten |last3=Harzsch |first3=Steffen |date=November 2024 |title=The eyestalk photophore of Northern krill Meganyctiphanes norvegica (M. Sars) (Euphausiacea) re-investigated: Innervation by specialized ommatidia of the compound eye |journal=Arthropod Structure & Development |volume=83 |article-number=101393 |doi=10.1016/j.asd.2024.101393 |issn=1873-5495 |pmid=39426244|bibcode=2024ArtSD..8301393K |doi-access=free }}</ref> These light-emitting organs work by being [[Catalysis|catalyzed]] by an [[enzyme]] [[luciferase]]. Krill can adjust and control the [[photophore]] to a certain extent.<ref>{{Cite web |title=Bioluminescence |url=https://education.nationalgeographic.org/resource/bioluminescence/ |access-date=2025-03-06 |website=education.nationalgeographic.org |language=en}}</ref>

==== Nervous System ====

The northern krill's [[nervous system]] controls its photophore organs and their compound eyes. The photophore organs are controlled by [[Hormone|hormonal]] and [[Neural pathway|neuron pathways]]. [[Hormone]]s such as [[serotonin]] and [[nitric oxide]] manage the bioluminescence in their organs. Photophore operation is controlled by the northern krill's compound eyes by the eyes [[Ommatidium|ommatidia]]. [[Ommatidium|Ommatidia]] are the cells that make up their compound eyes.<ref>{{Cite journal |last=Wulff |first=Verner J. |date=2021 |title=Photoreception |url=https://www.accessscience.com/content/article/a511400 |language=en |doi=10.1036/1097-8542.511400|url-access=subscription }}</ref> Part of the ommatidia's job is to send [[nerve signal]]s to the photophore located on the [[Eyestalk|eyestalks.]]<ref name="Krieger 101393"/> These [[axon]] sending [[nerve signal]]s allow the krill to control the light from the photophore.<ref>{{Cite journal |last1=Krönström |first1=Jenny |last2=Dupont |first2=Samuel |last3=Mallefet |first3=Jerome |last4=Thorndyke |first4=Michael |last5=Holmgren |first5=Susanne |date=2007-09-15 |title=Serotonin and nitric oxide interaction in the control of bioluminescence in northern krill, Meganyctiphanes norvegica (M. Sars) |url=https://journals.biologists.com/jeb/article/210/18/3179/17031/Serotonin-and-nitric-oxide-interaction-in-the |journal=Journal of Experimental Biology |volume=210 |issue=18 |pages=3179–3187 |doi=10.1242/jeb.002394 |pmid=17766295 |bibcode=2007JExpB.210.3179K |issn=0022-0949|url-access=subscription }}</ref>

Another essential part of the northern krill's [[nervous system]] is the [[brain]]. While small it is still majorly important in processing [[sensory information]] and coordinating behavior. To control the northern krill's swimming and food behaviors their appendages such as their [[swimmerets]] are controlled by a chain of [[Ganglion|ganglia]] which make up a [[ventral nerve cord]]. This nerve cord controls the [[motor functions]] of the krill and their appendages.

== Reproduction ==

Northern krill [[Reproduction|reproduce]] seasonally, their eggs hatching during the spring and summer months. Reproduction tends to mirror the krill's access to food. During spring and summer months their food source [[phytoplankton]] bloom and provide nutrition for their hatched larvae. Northern krill have [[sexual dimorphism]], meaning that males and females have different reproductive structures.<ref>{{Citation |last=Cuzin-Roudy |first=Janine |title=Reproduction in Northern Krill (Meganyctiphanes norvegica Sars) |date=2010-01-01 |series=Advances in Marine Biology |volume=57 |pages=199–230 |editor-last=Tarling |editor-first=Geraint A. |url=https://www.sciencedirect.com/science/article/abs/pii/B9780123813084000078 |access-date=2025-03-10 |publisher=Academic Press|doi=10.1016/B978-0-12-381308-4.00007-8 |pmid=20955893 |isbn=978-0-12-381308-4 |url-access=subscription }}</ref> Females are usually smaller and have a chamber where fertilized eggs are stored and released, while males have modified pleopods specialized to transfer sperm to the female. With these appendages, males transfer packets of sperm (spermatophores). Up to 10,000 eggs can be oviparous at once. Females latch onto their eggs externally before releasing them near the surface. The eggs sink before hatching into swimming nauplius larvae.<ref>{{Cite web |title=Krill - Behavior, Diet, and Life Cycle |url=https://marinesanctuary.org/blog/krill-behavior-diet-lifecycle/#:~:text=Female%20krill%20can%20lay%20as,10-day%20period%20before%20hatching. |access-date=2025-03-10 |website=National Marine Sanctuary Foundation |language=en-US}}</ref>

==References==

{{Reflist}}

== External links ==

*{{cite web |url=http://nlbif.eti.uva.nl/bis/crustacea.php?menuentry=soorten&id=8 |title=''Meganyctiphanes norvegica'' (M. Sars, 1857) |work=Macrobenthos of the North Sea: Crustacea |publisher=[[University of Amsterdam|Universiteit van Amsterdam]]}}

*{{cite web |url=http://species-identification.org/species.php?species_group=euphausiids&id=47 |title=''Meganyctiphanes norvegica'' (M. Sars, 1857) |work=Euphausiids of the World |publisher=Marine Species Identification Portal}}

*{{cite web |url=http://www.arcodiv.org/watercolumn/euphausiid/Meganyctiphanes_norvegica.html |title=''Meganyctiphanes norvegica'' (M. Sars, 1857) |work=Arctic Ocean Diversity |author=Alexei Pinchuk & Russ Hopcroft |date=September 3, 2010}}

*{{Commons category-inline|Meganyctiphanes norvegica|''Meganyctiphanes norvegica''}}

{{Taxonbar|from=Q134974}}

{{DEFAULTSORT:Northern Krill}}

[[Category:Krill]]

[[Category:Crustaceans of the Atlantic Ocean]]

[[Category:Crustaceans described in 1856]]