Hagfish
Pacific hagfish resting on bottom 280 m depth off Oregon coast
Scientific classification
Kingdom: Animalia Phylum: Chordata Subphylum: Craniata Class: Myxini Order: Myxiniformes Family: Myxinidae
Genera
Eptatretus Myxine Nemamyxine Neomyxine Notomyxine Paramyxine Quadratus To meet Wikipedias quality standards, this article or section may require cleanup. ... Image File history File linksMetadata Pacific_hagfish_Myxine. ... This article is about the U.S. state. ... Scientific classification redirects here. ... For other uses, see Animal (disambiguation). ... Typical Classes See below Chordates (phylum Chordata) are a group of animals that includes the vertebrates, together with several closely related invertebrates. ... Classes Hyperotreti Vertebrata Craniata is a type of chordate animal group that contains vertebrates (vertebrata) and hagfish (Hyperotreti). ... For other uses, see Genus (disambiguation). ...

Hagfish are marine craniates of the class Myxini, also known as Hyperotreti. Myxini is the only class in the clade Craniata that does not also belong to the subphylum Vertebrata.^[1] That is, they are the only animals which have a skull but not a vertebral column. A clade is a term belonging to the discipline of cladistics. ... For other uses, see phyla. ... Typical classes Petromyzontidae (lampreys) Placodermi - extinct Chondrichthyes (cartilaginous fish) Acanthodii - extinct Actinopterygii (ray-finned fish) Actinistia (coelacanths) Dipnoi (lungfish) Amphibia (amphibians) Reptilia (reptiles) Aves (birds) Mammalia (mammals) Vertebrata is a subphylum of chordates, specifically, those with backbones or spinal columns. ... For other uses of Skull, see Skull (disambiguation). ... The vertebral column seen from the side Different regions (curvatures) of the vertebral column The vertebral column (backbone or spine) is a column of vertebrae situated in the dorsal aspect of the abdomen. ...

Despite their name, there is some debate about whether they are strictly fish (as there is for lampreys), since they belong to a much more primitive lineage than any other group that is commonly defined fish (Chondrichthyes and Osteichthyes). Their unusual feeding habits and slime-producing capabilities have led members of the scientific and popular media to dub the hagfish as the most "disgusting" of all sea creatures.^[2][3][4] Although hagfish are sometimes called "slime eels," they are not eels at all. ^[5] For other uses, see Fish (disambiguation). ... For other uses, see Lamprey (disambiguation). ... For other uses, see Fish (disambiguation). ... Subclasses and Orders See text. ... Classes Actinopterygii Sarcopterygii Osteichthyes are a taxonomic superclass of fish, also called bony fish that includes the ray-finned fish (Actinopterygii) and lobe finned fish (Sarcopterygii). ...

Physical characteristics

Body features

Hagfish average about half a metre (18 in) long; The largest known species is Eptatretus goliath with a specimen recorded at 127 cm, while Myxine kuoi and Myxine pequenoi seem to reach no more than 18 cm. This article is about the unit of length. ... An inch (plural: inches; symbol or abbreviation: in or, sometimes, ″ - a double prime) is the name of a unit of length in a number of different systems, including English units, Imperial units, and United States customary units. ... A centimetre (American spelling centimeter, symbol cm) is a unit of length that is equal to one hundredth of a metre, the current SI base unit of length. ...

Hagfish have elongated, eel-like bodies, and paddle-like tails. They have cartilaginous skulls and tooth-like structures composed of keratin. Colours depend on the species, ranging from pink to blue-grey, and may have black or white spots. Eyes may be vestigial or absent. Hagfish have no true fins and have six barbels around the mouth and a single nostril. Instead of vertically articulating jaws like Gnathostomata (vertebrates with jaws), they have a pair of horizontally moving structures with tooth-like projections for pulling off food. A paddle is a tool, originally a propulsion implement for mixing or pushing against liquids, typically in order to propel a boat. ... A scorpion tail The tail is the section at the rear end of an animals body; in general, the term refers to a distinct, flexible appendage to the torso. ... Cartilage is a type of dense connective tissue. ... For other uses of Skull, see Skull (disambiguation). ... Teeth redirects here. ... Not to be confused with kerogen or carotene. ... Color is an important part of the visual arts. ... For other uses, see Species (disambiguation). ... This article is about the color. ... This article is about the colour. ... Achromatic redirects here. ... This article is about the color. ... This article is about the color. ... For other uses, see Eye (disambiguation). ... A fin is a surface used to produce lift and thrust or to steer while traveling in water, air, or other fluid media. ... This koi carp has two pairs of barbels, the second pair being quite small. ... A nostril is one of the two channels of the nose, from the point where they bifurcate to the external opening. ... Human jaw front view Human jaw left view Human jaw top view The jaw is either of the two opposable structures forming, or near the entrance to, the mouth. ... Classes Placodermi Chondrichthyes Acanthodii Osteichthyes Gnathostomata is the group of vertebrates with jaws. ... This article does not cite any references or sources. ... Horizontal is an orientation relating to, or in parallel with the horizon, and thus perpendicular to the vertical. ...

Circulatory system

The circulatory systems of the hagfish have both closed and open blood vessels, with a heart system that is more primitive than that of vertebrates, bearing some resemblance to that of some worms. This system comprises a "brachial heart", which functions as the main pump, and three types of accessory hearts: the "portal" heart(s) which carry blood from intestines to liver, the "cardinal" heart(s) which move blood from the head to the body, and the "caudal" heart(s) which pump blood from the trunk and kidneys to the body. None of these hearts are innervated, so their function is probably modulated, if at all, by hormones. For transport in plants, see Vascular tissue. ... f you all The blood vessels are part of the circulatory system and function to transport blood throughout the body. ... The heart and lungs, from an older edition of Grays Anatomy. ... A diagram of a thoracic vertebra. ... For other uses, see Worm (disambiguation). ... The heart and lungs, from an older edition of Grays Anatomy. ... For other uses, see Blood (disambiguation). ... The intestine is the portion of the alimentary canal extending from the stomach to the anus and, in humans and other mammals, consists of two segments, the small intestine and the large intestine. ... The liver is the largest internal organ in the human body, and is an organ present in vertebrates and some other animals. ... The kidneys are the organs that filter wastes (such as urea) from the blood and excrete them, along with water, as urine. ... Nerves (yellow) Nerves redirects here. ... Hormone is also the NATO reporting name for the Soviet/Russian Kamov Ka-25 military helicopter. ...

A group of pacific hagfish.

Slime

Hagfish are long, vermiform and can exude copious quantities of a sticky slime or mucus (from which the typical species Myxine glutinosa was named). When captured and held by the tail, they escape by secreting the fibrous slime, which turns into a thick and sticky gel when combined with water, and then cleaning off by tying themselves in an overhand knot which works its way from the head to the tail of the animal, scraping off the slime as it goes. Some authorities conjecture that this singular behavior may assist them in extricating themselves from the jaws of predatory fish. The "sliming" also seems to act as a distraction to predators, and free-swimming hagfish are seen to "slime" when agitated and will later clear the mucus off by way of the same traveling-knot behavior.^{[citation needed]} Look up slime, slimy in Wiktionary, the free dictionary. ... Mucus cells. ... The overhand knot is a type of knot. ...

An adult hagfish can secrete enough slime to turn a large bucket of water into gel in a matter of minutes.^{[citation needed]}

Eye

In December 2003, an article was published by the University of Queensland claiming the hagfish's eye as being significant to the evolution of more complex eyes.^[6] The University of Queensland (UQ) is the longest-established university in the state of Queensland, Australia, a member of Australias Group of Eight, and the Sandstone Universities. ... Diagram of major stages in the eyes evolution. ...

Reproduction

Very little is known about hagfish reproduction. In some species, sex ratio can be as high as 100:1 in favour of females. In other species, individual hagfish which are hermaphroditic, with both ovaries and testes, but the female gonads remain non-functional until the individual has reached a particular stage in the hagfish lifecycle, are not uncommon. Females typically lay 20 to 30 yolky eggs that tend to aggregate due to having Velcro-like tufts at either end. In zoology, a hermaphrodite is a species that contains both male and female sexual organs at some point during their lives. ... Human male anatomy The testicles, known medically as testes (singular testis), are the male generative glands in animals. ... The gonad is the organ that makes gametes. ... Velcro: hooks (left) and loops (right). ...

Hagfish do not have a larval stage, in contrast to lampreys, which have a long larval phase. A larval insect A larva (Latin; plural larvae) is a juvenile form of animal with indirect development, undergoing metamorphosis (for example, insects or amphibians). ... For other uses, see Lamprey (disambiguation). ...

Feeding

Hagfish enter both living and dead fish, feeding on the insides (polychaete marine worms are also prey). While having no ability to enter through skin, they often enter through natural openings such as the mouth, gills or anus and consume their prey from the inside out. They can be a great nuisance to fishermen, as they are known to infiltrate and devour a catch before it can be pulled to the surface. Subclasses Palpata Scoleoida Tomopteris from plankton The Polychaeta or polychaetes are a class of annelid worms, generally marine. ... Any worm that lives in a marine environment is considered a marine worm. ... This article is about the organ. ... For other uses, see Mouth (disambiguation). ... For other uses, see Gill (disambiguation). ... This article is about the bodily orifice. ...

Like leeches, they have a sluggish metabolism and can survive months between feedings.^{[citation needed]} For other uses, see Leech (disambiguation). ...

Classification

Drawing of a New Zealand hagfish.

There has been long discussion in scientific literature about the hagfish being non-vertebrate. Given their classification as Agnatha, Hagfish are seen as an elementary vertebrate in between Prevertebrate and Gnathostome. Thus their classification is as an invertebrate within subphylum Craniata. Binomial name Eptatretus cirrhatus (Forster, 1801) The New Zealand Hagfish (Eptatretus cirrhatus) is a hagfish of the genus Eptatretus, found in south and east Australia, and around New Zealand, at depths of between 40 and 700 metres. ... Invertebrate is an English word that describes any animal without a spinal column. ... Idealized agnatha. ... Classes Placodermi Chondrichthyes Acanthodii Osteichthyes Gnathostomata is the group of vertebrates with jaws. ... Classes Hyperotreti Vertebrata Craniata is a type of chordate animal group that contains vertebrates (vertebrata) and hagfish (Hyperotreti). ...

Recent molecular biology analyses tend to classify hagfish as invertebrates (see references) within subphylum Craniata, because of their short molecular evolutive distance from Vertebrata (sensu stricto). A single fossil of hagfish shows that there has been little evolutionary change in the last 300 million years.^[7] Molecular biology is the study of biology at a molecular level. ...

Genetic analysis

In recent years hagfish have become of special interest for genetic analysis investigating the relationships among chordates. It has also recently been discovered that the mucus excreted by the hagfish is unique in that it includes strong, threadlike fibres similar to spider silk. What is interesting about hagfish slime is that it is fibre-reinforced. No other slime secretion known is reinforced with fibres in the way hagfish slime is. The fibres are about as fine as spider silk (averaging 2 micrometres), but can be 12 cm long. When the coiled fibres leave the hagfishes' 'slime' gland, they unravel quickly to their full length without tangling. Research continues into potential uses for this or a similar synthetic gel or of the included fibres. Some possibilities include new biodegradable polymers, space-filling gels, or a means of stopping blood flow in accident victims and surgery patients .^[8] Typical Classes See below Chordates (phylum Chordata) are a group of animals that includes the vertebrates, together with several closely related invertebrates. ... Mucus cells. ... Spider silk is a fibre secreted by spiders. ... A micrometre (American spelling: micrometer, symbol µm) is an SI unit of length equal to one millionth of a metre, or about a tenth of the diameter of a droplet of mist or fog. ... A coil is a series of loops. ... A polymer is a long, repeating chain of atoms, formed through the linkage of many molecules called monomers. ...

Species

Drawing of eptatretus minor

About 66 species are known, in 7 genera. A number of the species have only been recently discovered, living at depths of several hundred metres. Some of the species are listed here:

• Genus Eptatretus
  • Inshore hagfish, Eptatretus burgeri (Girard, 1855)
  • New Zealand hagfish, Eptatretus cirrhatus (Forster, 1801)
  • Black hagfish, Eptatretus deani (Evermann & Goldsborough, 1907)
  • Guadalupe hagfish, Eptatretus fritzi Wisner & McMillan, 1990
  • Eptatretus goliath Mincarone & Stewart, 2006
  • Sixgill hagfish, Eptatretus hexatrema (Müller, 1836)
  • Eptatretus lopheliae Fernholm & Quattrini, 2008
  • Shorthead hagfish, Eptatretus mcconnaugheyi Wisner & McMillan, 1990
  • Eptatretus mendozai Hensley, 1985
  • Eightgill hagfish, Eptatretus octatrema (Barnard, 1923)
  • Fourteen-gill hagfish, Eptatretus polytrema (Girard, 1855)
  • Fivegill hagfish, Eptatretus profundus (Barnard, 1923)
  • Cortez hagfish, Eptatretus sinus Wisner & McMillan, 1990
  • Gulf hagfish, Eptatretus springeri (Bigelow & Schroeder, 1952)
  • Pacific hagfish, Eptatretus stoutii (Lockington, 1878)
  • Eptatretus strickrotti Møller & Jones, 2007
• Genus Myxine
  • Patagonian hagfish Myxine affinis Günther, 1870
  • Myxine australis Jenyns, 1842
  • Cape hagfish, Myxine capensis
  • Whiteface hagfish, Myxine circifrons Garman, 1899
  • Myxine debueni Wisner & McMillan, 1995
  • Myxine dorsum Wisner & McMillan, 1995
  • Myxine fernholmi Wisner & McMillan, 1995
  • Myxine formosana Mok & Kuo, 2001
  • Myxine garmani Jordan & Snyder, 1901
  • Hagfish (or Atlantic hagfish), Myxine glutinosa
  • Myxine hubbsi Wisner & McMillan, 1995
  • Myxine hubbsoides Wisner & McMillan, 1995
  • White-headed hagfish, Myxine ios
  • Myxine jespersenae Møller, Feld, Poulsen, Thomsen & Thormar, 2005
  • Myxine knappi Wisner & McMillan, 1995
  • Myxine kuoi Mok, 2002
  • Myxine limosa Girard, 1859
  • Myxine mccoskeri Wisner & McMillan, 1995
  • Myxine mcmillanae Hensley, 1991
  • Myxine paucidens Regan, 1913
  • Myxine pequenoi Wisner & McMillan, 1995
  • Myxine robinsorum Wisner & McMillan, 1995
  • Myxine sotoi Mincarone, 2001
• Genus Nemamyxine
  • Nemamyxine elongata Richardson, 1958
  • Nemamyxine kreffti McMillan and Wisner, 1982
• Genus Neomyxine
  • Neomyxine biniplicata (Richardson and Jowett, 1951)
• Genus Notomyxine
  • Notomyxine tridentiger (Garman, 1899)
• Genus Paramyxine
  • Paramyxine atami Dean, 1904
  • Paramyxine cheni Shen and Tao, 1975
  • Paramyxine fernholmi Kuo, Huang and Mok, 1994
  • Paramyxine sheni Kuo, Huang and Mok, 1994
  • Paramyxine wisneri Kuo, Huang and Mok, 1994
• Genus Quadratus
  • Quadratus ancon Mok, Saavedra-Diaz and Acero P., 2001
  • Quadratus nelsoni (Kuo, Huang and Mok, 1994)
  • Quadratus taiwanae (Shen and Tao, 1975)
  • Quadratus yangi

Binomial name Eptatretus cirrhatus (Forster, 1801) The New Zealand Hagfish (Eptatretus cirrhatus) is a hagfish of the genus Eptatretus, found in south and east Australia, and around New Zealand, at depths of between 40 and 700 metres. ... Binomial name Eptatretus cirrhatus (Forster, 1801) The New Zealand Hagfish (Eptatretus cirrhatus) is a hagfish of the genus Eptatretus, found in south and east Australia, and around New Zealand, at depths of between 40 and 700 metres. ... The gulf hagfish is currently the only known species with the ability to enter brine pools, or pools of extremely high salt content, unharmed. ... The gulf hagfish is currently the only known species with the ability to enter brine pools, or pools of extremely high salt content, unharmed. ...

References

1. ^ N. A. Campbell and J. B. Reece (2005). Biology Seventh Edition. Benjamin Cummings, San Francisco CA.
2. ^ "Friends of Oceanography Public Lecture Series - Explores the Strange, Wondrous, and Disgusting Hagfish", University of Rhode Island, 2002-03-25. Retrieved on 2008-02-19. 
3. ^ Slimy, disgusting and useful. Norwegian University of Science and Technology. Retrieved on 2008-02-19.
4. ^ Frank (2004-08-09). Tammy. NOAA Ocean Explorer. Retrieved on 2008-02-19.
5. ^ Sea and Sky: Atlantic Hagfish
6. ^ Keeping an eye on evolution. PhysOrg.com (2007-12-03). Retrieved on 2007-12-04.
7. ^ Myxinidae Information. Mudminnow Information Services. Retrieved on 2008-02-19.
8. ^ Vowles, Andrew. From Slime to 'Bio-Steel'. University of Guelph. Retrieved on 2008-02-19.

• New species Eptatretus goliath. BIOONE Online Journals. Retrieved on 2008-02-19.
• J.M. Jørgensen, J.P. Lomholt, R.E. Weber and H. Malte (eds.) (1997). The biology of hagfishes. London: Chapman & Hall. 
• Delarbre et al (2002). "Complete Mitochondrial DNA of the Hagfish, Eptatretus burgeri: The Comparative Analysis of Mitochondrial DNA Sequences Strongly Supports the Cyclostome Monophyly". Molecular Phylogenetics and Evolution 22 (2): 184–192. 
• Bondareva and Schmidt (2003). "Early Vertebrate Evolution of the TATA-Binding Protein, TBP". Molecular Biology and Evolution 20 (11): 1932–1939. 
• Fudge, D. (2001). Hagfishes: Champions of Slime Nature Australia, Spring 2001 ed., Australian Museum Trust, Sydney. pp. 61–69.

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External links

Wikimedia Commons has media related to:

Myxini

• FishBase entry for Myxinidae
• OceanLink description of hagfish
• Tree of life illustration showing hagfish's relation to other organisms
• Quicktime movie of hagfish in repose and "sliming"

The subject of this article has been identified by the Missing Encyclopedic Articles project as being a high priority for expansion.

Image File history File links Commons-logo. ... Image File history File links Tietyö_142. ...