Editing Zooplankton (section)

==Overview==
{{plankton sidebar|trophic}}

'''Zooplankton''' ({{IPAc-en|ˈ|z|oʊ|.|ə|p|l|æ|ŋ|k|t|ən}};{{refn|{{Cite dictionary |url=http://www.lexico.com/definition/zooplankton |archive-url=https://web.archive.org/web/20200301210443/https://www.lexico.com/definition/zooplankton |url-status=dead |archive-date=March 1, 2020 |title=zooplankton |dictionary=[[Lexico]] UK English Dictionary |publisher=[[Oxford University Press]]}} }} {{IPAc-en|ˌ|z|oʊ|.|ə|ˈ|p|l|æ|ŋ|k|t|ən}}){{refn|{{cite Merriam-Webster|zooplankton}}}} are [[heterotroph]]ic (sometimes [[detritivore|detritivorous]]) [[plankton]]. The word ''zooplankton'' is derived from {{langx|grc|ζῷον|translit=zôion|lit=animal}}; and {{Langx|grc|πλᾰγκτός|translit=planktós|label=none|lit=wanderer; drifter}}.<ref>{{cite book |last=Thurman |first=H. V. |year=1997 |title=Introductory Oceanography |publisher=Prentice Hall College |location=New Jersey, USA |isbn=978-0-13-262072-7}}</ref>

Zooplankton is a categorization spanning a range of [[organism]] sizes including small [[protozoa]]ns and large [[metazoa]]ns. It includes [[holoplankton]]ic organisms whose complete [[biological life cycle|life cycle]] lies within the plankton, as well as [[meroplankton]]ic organisms that spend part of their lives in the plankton before graduating to either the [[nekton]] or a [[Sessility (zoology)|sessile]], [[benthos|benthic]] existence. Although zooplankton are primarily transported by ambient water currents, many have [[Animal locomotion|locomotion]], used to avoid predators (as in [[diel vertical migration]]) or to increase prey encounter rate.

Just as any species can be limited within a geographical region, so are zooplankton. However, species of zooplankton are not dispersed uniformly or randomly within a region of the ocean. As with phytoplankton, 'patches' of zooplankton species exist throughout the ocean. Though few physical barriers exist above the [[mesopelagic]], specific species of zooplankton are strictly restricted by salinity and temperature gradients, while other species can withstand wide temperature and salinity gradients.<ref name="Lalli and Parsons">{{cite book |author1=Lalli, C.M. |author2=Parsons, T.R. |name-list-style=amp |title=Biological Oceanography An Introduction |year=1993 |publisher=Elsevier |location=Burlington, MA |isbn=978-0-7506-3384-0 |pages=314}}</ref> Zooplankton patchiness can also be influenced by biological factors, as well as other physical factors. Biological factors include breeding, predation, concentration of phytoplankton, and vertical migration.<ref name="Lalli and Parsons"/> The physical factor that influences zooplankton distribution the most is mixing of the water column ([[upwelling]] and [[downwelling]] along the coast and in the open ocean) that affects nutrient availability and, in turn, phytoplankton production.<ref name="Lalli and Parsons"/>

Through their consumption and processing of phytoplankton and other food sources, zooplankton play a role in aquatic [[food web]]s, as a resource for consumers on higher [[trophic level]]s (including fish), and as a conduit for packaging the organic material in the [[biological pump]]. Since they are typically small, zooplankton can respond rapidly to increases in phytoplankton abundance,{{Clarify|date=March 2011}} for instance, during the [[spring bloom]]. Zooplankton are also a key link in the [[biomagnification]] of [[pollutant]]s such as [[Mercury (element)|mercury]].<ref>{{Cite web |date=2017-04-05 |title=How We Do Things at IISD-ELA: Researching Mercury |url=https://www.iisd.org/library/how-we-do-things-iisd-ela-researching-mercury |access-date=2020-07-06 |website=IISD |language=en}}</ref>

<gallery mode="packed" heights="360px" style="float:right;" caption="Typical models featuring zooplankton">
File:Typical ocean models featuring zooplankton 2.jpg|{{align|left|{{space|5}} Upper left: [[Marine biogeochemical cycles#Box models|Biogeochemical models]] {{space|22}} Right: [[Ecosystem model]]s}}<br />{{align|left|{{space|5}} Lower left: Size-spectra models}}<br />{{center|<small>These models also have temporal and spatial components.</small><ref>Everett, J.D., Baird, M.E., Buchanan, P., Bulman, C., Davies, C., Downie, R., Griffiths, C., Heneghan, R., Kloser, R.J., Laiolo, L. and Lara-Lopez, A. (2017) "Modeling what we sample and sampling what we model: challenges for zooplankton model assessment". ''Frontiers in Marine Science'', '''4''': 77. {{doi|10.3389/fmars.2017.00077}}. [[File:CC-BY icon.svg|50px]] Material was copied from this source, which is available under a [https://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International License].</ref>}}|alt=Upper left: Biogeochemical models                        Right: Ecosystem models      Lower left: Size-spectra modelsThese models also have temporal and spatial components.
</gallery>

[[Ecology|Ecologically]] important protozoan zooplankton groups include the [[foraminifera]]ns, [[radiolaria]]ns and [[dinoflagellate]]s (the last of these are often [[mixotroph]]ic). Important metazoan zooplankton include [[cnidaria]]ns such as [[jellyfish]] and the [[Portuguese Man o' War]]; [[crustacean]]s such as [[cladocera]]ns, [[copepod]]s, [[ostracod]]s, [[isopod]]s, [[amphipod]]s, [[mysids]] and [[krill]]; [[Chaetognatha|chaetognath]]s (arrow worms); [[Mollusca|molluscs]] such as [[pteropod]]s; and [[chordate]]s such as [[salp]]s and juvenile fish. This wide [[phylogeny|phylogenetic]] range includes a similarly wide range in feeding behavior: [[filter feeder|filter feeding]], [[predation]] and [[symbiosis]] with [[autotrophic]] [[phytoplankton]] as seen in corals. Zooplankton feed on [[bacterioplankton]], phytoplankton, other zooplankton (sometimes [[Cannibalism|cannibalistically]]), [[detritus]] (or [[marine snow]]) and even [[Nekton|nektonic organisms]]. As a result, zooplankton are primarily found in surface waters where food resources (phytoplankton or other zooplankton) are abundant.

Zooplankton can also act as a [[infectious disease|disease]] [[natural reservoir|reservoir]]. Crustacean zooplankton have been found to house the bacterium ''[[Vibrio cholerae]]'', which causes [[cholera]], by allowing the cholera vibrios to attach to their chitinous [[exoskeleton]]s. This [[symbiotic]] relationship enhances the bacterium's ability to survive in an aquatic environment, as the exoskeleton provides the bacterium with carbon and nitrogen.<ref>
{{cite journal |author1=Jude, B.A. |author2=Kirn, T.J. |author3=Taylor R.K. |title=A colonization factor links Vibrio cholerae environmental survival and human infection |journal=[[Nature (journal)|Nature]] |volume=438 |issue=7069 |pages=863–6 |year=2005 |pmid=16341015 |doi=10.1038/nature04249 |bibcode=2005Natur.438..863K |s2cid=1964530}}</ref>