Editing Zooplankton (section)

====Gelatinous zooplankton====
[[Gelatinous zooplankton]] include [[ctenophore]]s, [[Jellyfish|medusae]], [[salps]], and [[Chaetognatha]] in coastal waters. Jellyfish are slow swimmers, and most species form part of the plankton. Traditionally jellyfish have been viewed as [[Trophic level|trophic]] dead ends, minor players in the [[marine food web]], gelatinous organisms with a [[body plan]] largely based on water that offers little nutritional value or interest for other organisms apart from a few specialised predators such as the [[ocean sunfish]] and the [[leatherback sea turtle]].<ref name=Hamilton2016>Hamilton, G. (2016) [https://www.nature.com/news/polopoly_fs/1.19613!/menu/main/topColumns/topLeftColumn/pdf/531432a.pdf "The secret lives of jellyfish: long regarded as minor players in ocean ecology, jellyfish are actually important parts of the marine food web"]. ''Nature'', '''531'''(7595): 432–435. {{doi|10.1038/531432a}}</ref><ref name=Hays2018>[[Graeme Hays|Hays, G.C.]], Doyle, T.K. and Houghton, J.D. (2018) "A paradigm shift in the trophic importance of jellyfish?" ''Trends in ecology & evolution'', '''33'''(11): 874–884. {{doi|10.1016/j.tree.2018.09.001}}</ref> 

That view has recently been challenged. Jellyfish, and more gelatinous zooplankton in general, which include [[salp]]s and [[ctenophore]]s, are very diverse, fragile with no hard parts, difficult to see and monitor, subject to rapid population swings and often live inconveniently far from shore or deep in the ocean. It is difficult for scientists to detect and analyse jellyfish in the guts of predators, since they turn to mush when eaten and are rapidly digested.<ref name=Hamilton2016/> But jellyfish bloom in vast numbers, and it has been shown they form major components in the diets of [[tuna]], [[Tetrapturus|spearfish]] and [[swordfish]] as well as various birds and invertebrates such as [[octopus]], [[sea cucumber]]s, [[crab]]s and [[amphipod]]s.<ref>Cardona, L., De Quevedo, I.Á., Borrell, A. and Aguilar, A. (2012) "Massive consumption of gelatinous plankton by Mediterranean apex predators". ''PLOS ONE'', '''7'''(3): e31329. {{doi|10.1371/journal.pone.0031329}}</ref><ref name=Hays2018 /> "Despite their low energy density, the contribution of jellyfish to the energy budgets of predators may be much greater than assumed because of rapid digestion, low capture costs, availability, and selective feeding on the more energy-rich components. Feeding on jellyfish may make marine predators susceptible to ingestion of plastics."<ref name=Hays2018 /> According to a 2017 study, [[narcomedusae]] consume the greatest diversity of mesopelagic prey, followed by [[physonect]] [[siphonophore]]s, [[ctenophore]]s and [[cephalopod]]s.<ref name=Choy2017 /> 

<gallery mode="packed" heights="120px" style="float:left">
File:Parumbrosa polylobata 01.jpg| [[Jellyfish]]
File:Tunicate off Atauro island.jpg| This free-floating [[pyrosome]] is made up of hundreds of individual [[bioluminescent]] tunicates
File:23 salpchain frierson odfw (8253212250).jpg|[[Salp]] chain
</gallery>
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The importance of the so-called "jelly web" is only beginning to be understood, but it seems medusae, ctenophores and siphonophores can be key predators in deep pelagic food webs with ecological impacts similar to predator fish and squid. Traditionally gelatinous predators were thought ineffectual providers of marine trophic pathways, but they appear to have substantial and integral roles in deep [[pelagic food webs]].<ref name=Choy2017>Choy, C.A., Haddock, S.H. and Robison, B.H. (2017) "Deep pelagic food web structure as revealed by ''in situ'' feeding observations". ''Proceedings of the Royal Society B: Biological Sciences'', '''284'''(1868): 20172116. {{doi|10.1098/rspb.2017.2116}}. [[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>