For a fish without jaws, the hagfish is certainly no pushover, as recent deep-sea video footage of hagfishes in their natural environment demonstrates.
Hagfishes (Myxinidae) are well known for their ability to produce copious quantities of slime when provoked or stressed, utilising a large battery of slime glands and 90 to 200 associated slime pores running laterally along the full length of each side of their body.
Scientists have long suspected that hagfishes gag and choke predators by clogging their gills with slime.
Vincent Zintzen and coauthors have now provided visual evidence that hagfish slime indeed works this way defensively, reporting their findings in a recent issue of the online journal Scientific Reports.
The authors used baited remote underwater stereo-video units deployed at three locations along New Zealand’s northern coast: White Island, Great Barrier Island and the Three Kings Islands.
The authors recorded 14 instances where hagfishes were attacked by predators, including sharks, dogfishes, conger eels, cuskeels, raftfishes, scorpionfishes and wreckfishes. In each case, the hagfish discharged jets of slime into the predator’s mouth, causing it to visibly choke and move away.
The predators were then seen to convulse their gill arches dramatically in a gagging-type effort to clear the slime from their gill chambers. The hagfishes were nonchalant about being almost eaten, in many cases continuing to feed on the bait as the predators moved away.
Hagfishes are also notorious for their disgusting dietary habits, burrowing deep into corpses and eating their way out. However, video footage provided by the authors dispels the widely held notion that they are mere carrion feeders. In the footage, hagfishes were shown to be active predators, chasing after and dragging fish out of their burrows to eat them.
A slender hagfish (Neomyxine) was observed to chase a Red bandfish (Cepola haastii) into its burrow, knotting its tail for additional leverage to invade the burrow. After capturing the bandfish in its burrow , the hagfish presumably suffocated it by producing vast quantities of slime before unknotting itself and swimming out of the burrow with its meal.
For more information, see the paper: Zintzen, V, CD Roberts, MJ Anderson, AL Stewart, CD Struthers and ES Harvey (2011) Hagfish predatory behaviour and slime defence mechanism. Scientific Reports 1, article 131 doi:10.1038/srep00131
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