Family MYXINIDAE


Common name: Hagfishes

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Summary:

Primitive eel-like fishes found worldwide, mostly in temperate regions. They have naked eel-like bodies with 1-16 pairs of external gill openings on each side, no paired fins and no dorsal fin, and the caudal fin extending onto the upper and lower surface. Hagfish have degenerate eyes, a jawless mouth surrounding by barbels and horny rasping teeth on the tongue. They produce enormous amounts of slime to avoid predation.


Cite this page as:
Dianne J. Bray, Hagfishes, MYXINIDAE in Fishes of Australia, accessed 20 Sep 2019, http://fishesofaustralia.net.au/home/family/301

More Info


Family Taxonomy

The family comprises 7 genera and about 76 species separated into two subfamilies: Myxininae with one common gill opening on each side and Eptatretinae with 5-16 openings on each side. A single genus, Eptatretus, and four descibed species are known to occur Australian waters (Mincarone & Fernholm 2010). Relatively little material has been collected in Australia and additional species may occur here. Fossil hagfishes date back 300 million years ago.

Family Distribution

Hagfishes are marine bottom-dwelling fishes found in all oceans. Most species have an antitropical distribution and prefer to live on soft bottoms in cool temperate waters from six to 1300 metres.

Family Size

To 1.1 metres.

Family Colour

Generally greyish or brownish in colour.

Family Feeding

Hagfishes scavenge on dead or dying marine life, primarily on fishes and invertebrates, but also on marine mammals that have sunk to the ocean floor. They also prey on living fishes and invertebrates.

They produce enormous amounts of an incredibly sticky slime to protect themselves by clogging up the mouths and gills of their predators. They feed by rasping flesh, often going completely inside sunken carcasses and feeding from the inside out. Recent studies have shown that hagfishes also 'feed' by absorbing nutrients through their permeable skin and gills.

Family Reproduction

Both sterile and hermaphroditic individuals have been found. Spawning and fertilisation may occur in burrows. Hagfishes lay relatively few large eggs which they presumably attached to the substrate by filaments. There is no larval stage and young hagfishes develop directly from the egg.

Family Commercial

Although of no interest to Australian fisheries, hagfishes are commercially fished worldwide - slime eel fishing - and are heavily exploited in some regions. Not only are hagfishes consumed along with their eggs and slime, their skins are tanned, made into leather and marketed as "eelskin". Hagfish populations in some areas are threatened by overfishing. The copious amounts of slime they produce is problematic for commercial fishers using baited traps in deeper waters.

Hagfishes are consumed as food in Aisa.

Family Conservation

Hagfishes have been recently assessed using the International Union for Conservation of Nature (IUCN) criteria, and 9 of the 76 known hagfish species were found to be threatened, including species found in southern Australia (Knapp et al. 2011). Threats include overfishing and habitat destruction.

Family Remarks

When threatened, hagfishes secrete a gelatinous slime containing mucus and thousands of intermediate filament protein threads that are manufactured within specialized gland thread cells. The protein threads are extremely strong and incredibly long, and are able to rapidly uncoil without becoming tangled. (Winegard et al. 2014)

Author

Dianne J. Bray

References


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Fudge, D., Levy, N., Chiu, S. & Gosline, J. 2005. Composition, morphology and mechanics of hagfish slime. J. Exp. Biol. 208: 4613–4625.

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Negishi, A., C.L. Armstrong, L. Kreplak, M.C. Rheinstadter, L-T. Lim , T.E. Gillis & D.S. Fudge. 2012. The production of fibers and films from solubilized hagfish slime thread proteins. Biomacromolecules 13: 3475–3482. PDF

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Winegard, T. & Fudge, D. 2010. Deployment of hagfish thread skeins requires the transmission of mixing forces via mucin strands. J. Exp. Biol. 213: 1235–1240.

Winegard, T., J. Herr, C. Mena, B. Lee, I. Dinov, D. Bird, M. Bernards, S. Hobel, B. Van Valkenburgh, A. Toga & D. Fudge. 2014. Coiling and maturation of a high-performance fibre in hagfish slime gland thread cells. Nature Communications 2014; 5 DOI: 10.1038/ncomms4534 Abstract

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