Editing Hagfish (section)

==Feeding==
[[Image:Pacific hagfish feeding 01.jpg|thumb|left|Two Pacific hagfish feeding on a dead sharpchin rockfish, ''[[Sebastes zacentrus]]'', while one remains in a curled position at the left of the photo]]
While [[polychaete]] [[marine worm]]s on or near the sea floor are a major food source, hagfish can feed upon and often even enter and eviscerate the bodies of dead and dying/injured sea creatures much larger than themselves. They are known to devour their prey from the inside.<ref>Wilson, Hugh (November 2009) [https://web.archive.org/web/20091116002431/http://green.ca.msn.com/green-living/gallery.aspx?cp-documentid=22580760&page=6 Hagfish – World's weirdest animals]. green.ca.msn.com</ref> Hagfish have the ability to absorb dissolved organic matter across the skin and gill, which may be an adaptation to a scavenging lifestyle, allowing them to maximize sporadic opportunities for feeding. From an evolutionary perspective, hagfish represent a transitory state between the generalized nutrient absorption pathways of aquatic invertebrates and the more specialized digestive systems of aquatic vertebrates.<ref>{{cite journal|last1=Glover|first1=CN|last2=Bucking |first2=C |last3=Wood |first3=CM |title=Adaptations to in situ feeding: novel nutrient acquisition pathways in an ancient vertebrate|journal=Proceedings of the Royal Society B: Biological Sciences |date=2011-03-02|pmid=21367787|doi=10.1098/rspb.2010.2784|volume=278|issue=1721|pages=3096–101|pmc=3158932}}</ref>

Like [[leech]]es, they have a sluggish metabolism and can survive months between feedings;<ref>{{cite web|title=Introduction to the Myxini|url=http://www.ucmp.berkeley.edu/vertebrates/basalfish/myxini.html|access-date=2009-01-25|work=Berkeley.edu website|archive-url=https://web.archive.org/web/20171215173214/http://www.ucmp.berkeley.edu/vertebrates/basalfish/myxini.html|archive-date=2017-12-15|url-status=dead}}</ref><ref>{{cite journal|doi=10.1016/S0022-0981(96)02665-2|last1=Lesser|first1=M|title=Ecology of the hagfish, Myxine glutinosa L. in the Gulf of Maine I. Metabolic rates and energetics |journal=Journal of Experimental Marine Biology and Ecology | volume=208 | date=3 January 1997|issue=1–2 | pages=215–225|last2=Martini|first2=Frederic H.|last3=Heiser|first3=John B. |doi-access=|bibcode=1997JEMBE.208..215L }}</ref> their feeding behavior, however, appears quite vigorous. Analysis of the stomach content of several species has revealed a large variety of prey, including [[polychaete]]s, shrimp, [[hermit crab]]s, [[cephalopod]]s, [[brittle star]]s, [[bony fish]]es, sharks, birds, and whale flesh.<ref>{{Cite journal | doi = 10.3354/meps10341|url=https://www.int-res.com/articles/meps_oa/m485p223.pdf | title = Hagfish feeding habits along a depth gradient inferred from stable isotopes| journal = Marine Ecology Progress Series| volume = 485| pages = 223–234| year = 2013| last1 = Zintzen | first1 = V. | last2 = Rogers | first2 = K. M. | last3 = Roberts | first3 = C. D. | last4 = Stewart | first4 = A. L. | last5 = Anderson | first5 = M. J. | bibcode = 2013MEPS..485..223Z| doi-access = free }}</ref>

In captivity, hagfish are observed to use the overhand-knot behavior in reverse (tail-to-head) to assist them in gaining mechanical advantage to pull out chunks of flesh from carrion fish or cetaceans, eventually making an opening to permit entry to the interior of the body cavity of larger carcasses. A healthy larger sea creature likely would be able to outfight or outswim this sort of assault.

This energetic opportunism on the part of the hagfish can be a great nuisance to fishermen, as they can devour or spoil entire deep drag-netted catches before they can be pulled to the surface. Since hagfish are typically found in large clusters on and near the bottom, a single trawler's catch could contain several dozen or even hundreds of hagfish as bycatch, and all the other struggling, captive sea life make easy prey for them.

The digestive tract of the hagfish is unique among chordates because the food in the gut is enclosed in a permeable membrane, analogous to the [[peritrophic matrix]] of insects.<ref>[[Ross Piper|Piper, Ross]] (2007), ''Extraordinary Animals: An Encyclopedia of Curious and Unusual Animals'', [[Greenwood Press (publisher)|Greenwood Press]].</ref> They are also able to absorb nutrients directly through their skin.<ref>{{Cite web |last=Reardon |first=Sara |date=2 March 2011 |title=Hagfish Just Got More Disgusting |url=https://www.science.org/content/article/hagfish-just-got-more-disgusting |access-date=30 August 2024 |website=[[Science (journal)|Science]] |archive-date=29 August 2024 |archive-url=https://web.archive.org/web/20240829211417/https://www.science.org/content/article/hagfish-just-got-more-disgusting |url-status=live }}</ref>

Hagfish have also been observed actively [[predation|hunting]] the red bandfish, ''[[Cepola haastii]]'', in its burrow, possibly using their slime to suffocate the fish before grasping it with their dental plates and dragging it from the burrow.<ref>{{Cite journal | last1 = Zintzen | first1 = V. | last2 = Roberts | first2 = C. D. | last3 = Anderson | first3 = M. J. | last4 = Stewart | first4 = A. L. | last5 = Struthers | first5 = C. D. | last6 = Harvey | first6 = E. S. | title = Hagfish predatory behaviour and slime defence mechanism | doi = 10.1038/srep00131 | journal = Scientific Reports | volume = 1 | pages = 131 | year = 2011 | pmid =  22355648| pmc = 3216612| bibcode = 2011NatSR...1E.131Z }}</ref>