Editing Blue whale (section)

===Diet and feeding===
[[File:Blue-whale.jpg|thumb|alt=Photograph blue whale near surface with throat bulging | Blue near the surface after feeding]]
The blue whale's diet consists almost exclusively of [[krill]].<ref name=Sears_Perr_2009/> Blue whales capture krill through lunge feeding; they swim towards them at high speeds as they open their mouths up to 80°.<ref name=Sears_Perr_2009/><ref name=Goldbogen_etal_2011/> They may engulf {{convert|220|t|sp=us}} of water at one time.<ref name=Fossette_etal_2017>{{cite journal | author1=Fossette, S. | author2=Abrahms, B. | author3=Hazen, E. L. | author4=Bograd, S. J. | author5=Zilliacus, K. M. | author6=Calambokidis, J. | author7=Burrows, J. A. | author8=Goldbogen, J. A. | author9=Harvey, J. T. | author10=Marinovic, B. | author11=Tershy, B. | author12=Croll, D. A. | title=Resource partitioning facilitates coexistence in sympatric cetaceans in the California Current | journal=[[Ecology and Evolution]] | volume=7 | issue=1 | pages=9085–9097 | date=2017| doi=10.1002/ece3.3409 | pmid=29152200 | pmc=5677487 | bibcode=2017EcoEv...7.9085F }}</ref> They squeeze the water out through their baleen plates with pressure from the throat pouch and tongue, and swallow the remaining krill.<ref name=Sears_Perr_2009/><ref name=Goldbogen_etal_2011>{{cite journal | author1=Goldbogen, J. A. | author2=Calambokidis, J. | author3=Oleson, E. | author4=Potvin, J.|author5-link=Nicholas Pyenson | author5=Pyenson, N. D. | author6=Schorr, G. | author7=Shadwick, R. E. | title=Mechanics, hydrodynamics and energetics of blue whale lunge feeding: Efficiency dependence on krill density | journal=Journal of Experimental Biology | volume=214 | issue=1 | pages=131–46 | date=2011| doi=10.1242/jeb.048157 | pmid=21147977 | doi-access=free | bibcode=2011JExpB.214..131G }}</ref> Blue whales have been recorded making 180° rolls during lunge-feeding, possibly allowing them to search the prey field and find the densest patches.<ref name=Goldbogen_etal_2012>{{cite journal | author1=Goldbogen, J. A. | author2=Calambokidis, J. | author3=Friedlaender, A. S. | author4=Francis, J. | author5=DeRuiter, A. L. | author6=Stimpert, A. K. | author7=Falcone, E. | author8=Southall, B. L. | title=Underwater acrobatics by the world's largest predator: 360° rolling manoeuvres by lunge-feeding blue whales | journal=[[Biology Letters]] | volume=9 | issue=1 | doi=10.1098/rsbl.2012.0986 | pmid=23193050 | pmc=3565519 | page=20120986 | date=2012}}</ref>

While pursuing krill patches, blue whales maximize their calorie intake by increasing the number of lunges while selecting the thickest patches. This provides them enough energy for everyday activities while storing additional energy necessary for migration and reproduction. Due to their size, blue whales have larger energetic demands than most animals resulting in their need for this specific feeding habit.<ref>{{Cite web |last=Barlow |first=Dawn R. |date=2023 |title=Shaped by their Environment: Variation in Blue Whale Morphology Across Three Productive Coastal Ecosystems |url=https://academic.oup.com/iob/article/5/1/obad039/7438866 |access-date=23 November 2024 |website=Integrative Organismal Biology}}</ref> Blue whales have to engulf densities greater than 100 krill/m<sup>3</sup> to maintain the cost of lunge feeding.<ref name=Goldbogen_etal_2011/><ref name=Hazen_etal_2015>{{cite journal | author1=Hazen, E. L. | author2=Friedlaender, A. S. | author3=Goldbogen, J. A. | title=Blue whales ("Balaenoptera musculus") optimize foraging efficiency by balancing oxygen use and energy gain as a function of prey density | journal=Science Advances | volume=1 | issue=9 | page=e1500469 | date=2015| bibcode=2015SciA....1E0469H | doi=10.1126/sciadv.1500469 | pmid=26601290 | pmc=4646804 | doi-access=free }}</ref> They can consume {{convert|34,776|–|1,912,680|kJ|kcal|sp=us}} from one mouthful of krill, which can provide up to 240 times more energy than used in a single lunge.<ref name=Goldbogen_etal_2011/> It is estimated that an average-sized blue whale must consume {{convert|1,120|±|359|kg|sp=us}} of krill a day.<ref name=Brodie_1975>{{cite journal | author1=Brodie, P. F. | title=Cetacean energetics, an overview of intraspecific size variation | journal=Ecology | volume=56 | issue=1 | pages=152–161 | date=1975| doi=10.2307/1935307 | jstor=1935307 | bibcode=1975Ecol...56..152B }}</ref><ref name=Croll_etal_2006>{{cite book | author1=Croll, D. A. | author2=Kudela, R. | author3=Tershy, B. R. | title=Whales, Whaling and Ocean Ecosystems | chapter=Ecosystem impact of the decline of large whales in the North Pacific | publisher=University of California Press | location=Berkeley, CA | editor1-last=Estes | editor1-first=J. A. | pages=202–214 | date=2006}}</ref>  On average, a blue whale eats {{cvt|4|t|sp=}} each day.<ref name=natgeo/>

In the southern ocean, blue whales feed on [[Antarctic krill]] (''Euphausia superba''). In the South Australia, pygmy blue whales (''B. m. brevicauda'') feeds on ''[[Nyctiphanes australis]]''.<ref name=":1">{{Cite journal |last1=de Vos |first1=Asha |last2=Faux |first2=Cassandra E. |last3=Marthick |first3=James |last4=Dickinson |first4=Joanne |last5=Jarman |first5=Simon N. |date=6 April 2018 |title=New Determination of Prey and Parasite Species for Northern Indian Ocean Blue Whales |journal=Frontiers in Marine Science |language=English |volume=5 |doi=10.3389/fmars.2018.00104 |doi-access=free |issn=2296-7745}}</ref> In California, they feed mostly on ''[[Thysanoessa spinifera]],'' but also less commonly on North pacific krill (''[[Euphausia pacifica]]'').<ref>{{Cite journal |last1=Fiedler |first1=Paul C. |last2=Reilly |first2=Stephen B. |last3=Hewitt |first3=Roger P. |last4=Demer |first4=David |last5=Philbrick |first5=Valerie A. |last6=Smith |first6=Susan |last7=Armstrong |first7=Wesley |last8=Croll |first8=Donald A. |last9=Tershy |first9=Bernie R. |last10=Mate |first10=Bruce R. |date=1 August 1998 |title=Blue whale habitat and prey in the California Channel Islands |url=https://www.sciencedirect.com/science/article/abs/pii/S0967064598800179 |journal=Deep Sea Research Part II: Topical Studies in Oceanography |volume=45 |issue=8 |pages=1781–1801 |doi=10.1016/S0967-0645(98)80017-9 |bibcode=1998DSRII..45.1781F |issn=0967-0645}}</ref> Research of the Eastern North Pacific population shows that when diving to feed on krill, the whales reach an average depth of 201 meters, with dives lasting 9.8 minutes on average.<ref name=":1" />

While most blue whales feed almost exclusively on krill, the Northern Indian Ocean subspecies (''B. m. indica'') instead feeds predominantly on [[Sergestidae|sergestid]] shrimp. To do so, they dive deeper and for longer periods of time than blue whales in other regions of the world, with dives of 10.7 minutes on average, and a hypothesized dive depth of about 300 meters. Fecal analysis also found the presence of fish, krill, [[Amphipoda|amphipods]], [[cephalopod]]s, and [[Scyphozoa|scyphozoan jellyfish]] in their diet.<ref name=":1" />

Blue whales appear to avoid directly competing with other baleen whales.<ref name=Hardin_1960>{{cite journal | author1=Hardin, G. | s2cid=18542809 | title=The competitive exclusion principle | journal=Science | volume=131 | issue=3409 | pages=1292–1297 | date=1960| doi=10.1126/science.131.3409.1292 | pmid=14399717 | bibcode=1960Sci...131.1292H }}</ref><ref name=Hutchinson_1961>{{cite journal | author1=Hutchinson, G. E. | s2cid=86353285 | title=The Paradox of the Plankton | journal=[[The American Naturalist]] | volume=95 | issue=882 | pages=137–145 | date=1961| doi=10.1086/282171 | bibcode=1961ANat...95..137H }}</ref><ref name=Pianka_1974>{{cite journal | author1=Pianka, E. R. | title=Niche overlap and diffuse competition | journal=Proceedings of the National Academy of Sciences | volume=71 | issue=5 | pages=2141–2145 | date=1974| doi=10.1073/pnas.71.5.2141 | pmid=4525324 | pmc=388403 | bibcode=1974PNAS...71.2141P | doi-access=free }}</ref> Different whale species select different feeding spaces and times as well as different prey species.<ref name=Fossette_etal_2017/><ref name=Doniol-Valcroze_2008>{{cite thesis | author1=Doniol-Valcroze, T. | title=Habitat selection and niche characteristics of rorqual whales in the northern Gulf of St. Lawrence (Canada) | type=PhD | publisher=[[McGill University]] | location=Montreal, Canada | date=2008}}</ref><ref name=Friedlaender_etal_2015>{{cite journal | author1=Friedlaender, A. S. | author2=Goldbogen, J. A. | author3=Hazen, E. L. | author4=Calambokidis, J. | author5=Southall, B. L. | title=Feeding performance by sympatric blue and fin whales exploiting a common prey resource | journal=Marine Mammal Science | volume=31 | issue=1 | pages=345–354 | date=2015| doi=10.1111/mms.12134 | bibcode=2015MMamS..31..345F }}</ref> In the [[Southern Ocean]], baleen whales appear to feed on [[Antarctic krill]] of different sizes, which may lessen competition between them.<ref name=Santora_etal_2010>{{cite journal | author1=Santora, J. A. | author2=Reiss, C. S. | author3=Loeb, V. J. | author4=Veit, R. R. | title=Spatial association between hotspots of baleen whales and demographic patterns of Antarctic krill ''Euphausia superba'' suggests size-dependent predation | journal=Marine Ecology Progress Series | volume=405 | pages=255–269 | date=2010| doi=10.3354/meps08513 | bibcode=2010MEPS..405..255S | doi-access=free }}</ref>

Blue whale feeding habits may differ due to situational disturbances, like environmental shifts or human interference. This can cause a change in diet due to stress response. Due to these changing situations, there was a study performed on blue whales measuring cortisol levels and comparing them with the levels of stressed individuals, it gave a closer look to the reasoning behind their diet and behavioral changes.<ref>{{Cite web |last=Melica |first=Valentina |date=2020 |title=Reproduction and Stress Response Endocrinology in Blue (Balaenoptera musculus) and Gray (Eschrichtius robust) Whales |url=https://scholarworks.alaska.edu/bitstream/handle/11122/12414/Melica_V_2020.pdf |access-date=23 November 2024 |website=Scholarworks Alaska}}</ref>