{{Short description|Species of crustacean}} {{Speciesbox | image = | genus = Neocalanus | species = plumchrus | authority = (Marukawa, 1921) | synonyms = * ''Calanus plumchrus'' <small>Marukawa, 1921</small> * ''Calanus tonsus plumchrus'' <small>Fulton, 1968</small> | synonyms_ref = <ref name=WoRMS/> }}
'''''Neocalanus plumchrus''''' is a large species of copepod found in the Pacific and Arctic Oceans. It was described in 1921 H. by Marukawa. ''N. flemingeri'' was formerly considered as conspecific, likely as a form, until it was split in 1988 by Charles B. Miller.
==Taxonomy and etymology== ''Neocalanus plumchrus'' was originally described by Marukawa in 1921.<ref name=WoRMS/> It was eventually moved by Janet Bradford and John Jillett in 1974 from the genus ''Calanus'' to its current placement in ''Neocalanus''. The species ''N. flemingeri'' was split out of this species in 1988, where it is considered by Charles B. Miller to have been placed as f. ''typica''.<ref name="Miller1988">{{cite journal|last1=Miller|first1=Charles B.|title=''Neocalanus flemingeri'', a new species of Calanidae (Copepoda: Calanoida) from the subarctic Pacific Ocean, with a comparative redescription of ''Neocalanus plumchrus'' (Marukawa) 1921 |journal=Progress in Oceanography|volume=20|issue=4|year=1988|pages=223–273 |doi=10.1016/0079-6611(88)90042-0}}</ref>
==Description== ''Neocalanus plumchrus'' is considered a large copepod,<ref name="BattenWelch2003"/> with females generally ranging from about {{convert|4|to|6.3|mm|in}} in length. The males are usually between about {{convert|4.2|and|5|mm|in}} in length.<ref name="copepoddiversity"/> Stage V copepodites usually are more than {{convert|4.3|mm|in}} in length.<ref name="MillerFrost1984"/> The females of ''N. plumchrus'', contrasting to those of ''N. flemingeri'', have convex first urosomal tagma. The cephalosome length to prosome length ratio is generally over 0.44. The spermatophore deposited in females lacks any coils. In males, the ratio of cephalosome length to prosome length is usually between 0.55 and 0.56. The first antenna extends beyond the caudal rami by multiple segments. In stage V copepodites, the colouration and the second from medial caudal seta (or II bristle) can be used to distinguish this species and ''N. flemingeri''. In ''N. plumchrus'', there is red-orange colouration along both of the first antennae, vertical stripes of colour along the sides of the thorax, and on the caudal rami. The II bristle is about {{convert|0.28|mm|in}} in diameter {{convert|0.5|mm|in}} from its base, and is over three times the length of the urosome when the former is in its entirety.<ref name="Miller1988"/>
==Distribution== In the Pacific, ''N. plumchrus'' is found in the Sea of Japan, the northern Pacific, and off California. It is also found in the Arctic Ocean.<ref name="copepoddiversity">{{cite web|author1=Razouls C.|author2=de Bovée F.|author3=Kouwenberg J.|author4=Desreumaux N.|url=https://copepodes.obs-banyuls.fr/en/fichesp.php?sp=522|title=Diversity and Geographic Distribution of Marine Planktonic Copepods|year=2018|access-date=15 July 2018|publisher=Sorbonne Université, CNRS}}</ref>
==Ecology== ===Life cycle and reproduction=== The timing of reproduction in ''N. plumchrus'' is variable; in the Strait of Georgia, it breeds between December and April,<ref name="Conover1988">{{cite journal|last1=Conover|first1=R. J.|title=Comparative life histories in the genera ''Calanus'' and ''Neocalanus'' in high latitudes of the Northern Hemisphere|journal=Hydrobiologia|volume=167|issue=1|year=1988|pages=127–142 |doi=10.1007/BF00026299}}</ref> whereas it breeds between July and February at Station P.<ref name="MillerFrost1984">{{cite journal|last1=Miller|first1=Charles B.|last2=Frost|first2=Bruce W.|last3=Batchelder|first3=Harold P.|last4=Clemons|first4=Martha J.|last5=Conway|first5=Richard E.|title=Life histories of large, grazing copepods in a subarctic ocean gyre: ''Neocalanus plumchrus'', ''Neocalanus cristatus'', and ''Eucalanus bungii'' in the Northeast Pacific|journal=Progress in Oceanography|volume=13|issue=2|year=1984|pages=201–243 |doi=10.1016/0079-6611(84)90009-0}}</ref> In both cases, it breeds at depth, usually below around {{convert|300|m|ft}} in the former, and below about {{convert|250|m|ft}} in the latter case.<ref name="Conover1988"/> It likely utilizes lipid stores to breed, instead of recently consumed food. After reproducing, the adults die; first the males, and then the females.<ref name="EvansonBornhold2000">{{cite journal|last1=Evanson|first1=M|last2=Bornhold|first2=EA|last3=Goldblatt|first3=RH|last4=Harrison|first4=PJ|last5=Lewis|first5=AG|title=Temporal variation in body composition and lipid storage of the overwintering, subarctic copepod ''Neocalanus plumchrus'' in the Strait of Georgia, British Columbia (Canada)|journal=Marine Ecology Progress Series|volume=192|year=2000|pages=239–247 |doi=10.3354/meps192239|doi-access=free}}</ref> Copepodite stages I through V develop in the surface waters (stages II through IV are found in the top {{convert|250|m|ft}} throughout the year in waters off Japan, for example) late during the phytoplankton bloom.<ref name="Kobari2001">{{cite journal|last1=Kobari|first1=T.|title=Ontogenetic vertical migration and life cycle of ''Neocalanus plumchrus'' (Crustacea: Copepoda) in the Oyashio region, with notes on regional variations in body sizes|journal=Journal of Plankton Research|volume=23|issue=3|year=2001|pages=287–302 |doi=10.1093/plankt/23.3.287|doi-access=}}</ref> Stage V copepodites enter diapause at depths of below {{convert|250|m|ft}}<ref name="MillerFrost1984"/> during late summer.<ref name="BattenWelch2003">{{cite journal|last1=Batten|first1=Sonia D.|last2=Welch|first2=David W.|last3=Jonas|first3=Tanya|title=Latitudinal differences in the duration of development of ''Neocalanus plumchrus'' copepodites|journal=Fisheries Oceanography|volume=12|issue=3|year=2003|pages=201–208 |doi=10.1046/j.1365-2419.2003.00233.x}}</ref> At Station P, the number of copepodites in diapause remains about the same until September, when numbers decrease due to mortality and development into adults.<ref name="Conover1988"/> This contrasts to the Strait of Georgia, where diapause is from July to January, and maturation occurs during January and February.<ref name="MillerFrost1984"/>
===Feeding=== ''Neocalanus plumchrus'' is, as a whole, omnivorous, although there are regional variations. In the Strait of Georgia, for example, this copepod is mainly herbivorous, whereas in the ocean, omnivory is more prevalent; this affects the composition of lipids, with oceanic samples having (likely as an adaptation to lower concentrations of food) more monounsaturated fats with 20 or 22 carbon atoms.<ref name="El-SabaawiDower2009">{{cite journal|last1=El-Sabaawi|first1=R|last2=Dower|first2=JF|last3=Kainz|first3=M|last4=Mazumder|first4=A|title=Interannual variability in fatty acid composition of the copepod ''Neocalanus plumchrus'' in the Strait of Georgia, British Columbia|journal=Marine Ecology Progress Series|volume=382|year=2009|pages=151–161 |doi=10.3354/meps07915|doi-access=free}}</ref> It is able to uptake glucose directly from seawater from its dermal glands and midgut, which arthropods were thought to be incapable of due to their rigid exoskeleton.<ref name="Chapman1981">{{cite journal|last1=Chapman|first1=Peter M.|title=Evidence for dissolved glucose uptake from seawater by ''Neocalanus plumchrus'' (Arthropoda, Copepoda)|journal=Canadian Journal of Zoology|volume=59|issue=8|year=1981|pages=1618–1621 |doi=10.1139/z81-223}}</ref>
==References== {{Reflist|30em|refs= <ref name=WoRMS>{{cite WoRMS |title=''Neocalanus plumchrus'' (Marukawa, 1921) |year=2023 |id=196772 |db=copepoda |access-date=30 June 2023}}</ref> }}
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Category:Calanoida Category:Crustaceans of the Arctic Ocean Category:Copepods of the Pacific Ocean Category:Crustaceans described in 1921