by Greg Mayer
I’m teaching vertebrate zoology this semester, and one of my favorite topics in the course is the hagfish. Hagfish are jawless, eel-like fish, whose closest relatives are lampreys. (They were once though to be more primitive than lampreys, but molecular data show the two to form a holophyletic group.) I was thus quite pleased to find that Vincent Zintzen from the Museum of New Zealand and colleagues have a recent paper in Scientific Reports on hagfish defensive and predatory behavior, with accompanying videos. There’s more at the website of Te Papa Tongarewa (which is the name of the museum in Maori).
Hagfish are well known for producing copious amounts of viscous slime to discourage predators. In the following video, what’s most remarkable to me is how rapidly the hagfish produces sufficient slime to almost instantaneously deter the predators.
Here’s a closeup of slime production from the Vancouver Aquarium:
And here’s a hagfish preying on a burrowing fish. Zintzen et al. suspect the fish has been killed or disabled by choking with slime while in the burrow.
Hagfish are usually thought of as scavengers (notice the cages of dead meat used as bait in the video). Here’s a more usual feeding episode: large numbers of hagfish gathering on a whale carcass. That sounds like David Attenborough doing the narration.
Finally, here’s an abridged, combined version of the Te Papa videos (if you want to get the under 4 minute version of the whole story):
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Zintzen V., Roberts, C.D., Anderson M.J., Stewart A.L., Struthers C.D. & Harvey E.S. 2011. Hagfish predatory behaviour and slime defence mechanism. Scientific Reports 1: 131, 6 pp. pdf (Scientific Reports is put out online-only by Nature Publishing Group; papers are given at least some peer review, but are not evaluated for how important or interesting they are.)
My wife’s favourite soft leather handbag was made from hagfish skin. Thin, luxuriously soft & pliant, yet tough as old boots. (The hand-bag, not the missus!)
I think that they are amongst my favourite animals, although I admit that they do not have the appeal of pandas.
That slime is amazing, it must taste bad surely, to have such a swift and profound effect.
Perhaps. It looks rather pure in the aquarium demo though, so I am guessing it is a rather simple gelatinous compound even before it adsorbs all that water.
And maybe it doesn’t have to taste anything, if it triggers a choke reflex as it reaches the gills.
For one, it would be something fishes could have developed to avoid suffocating in mud. (I am speculating here; but we have something similar to avoid lung blockage.)
For another, it would be along the choking use of that hunt video. If it works, it would be more robust and generic, no pesky predators specializing in ignoring the bad taste compounds. (Still speculating…)
I didn’t learn much on slime, but the usual suspect has it down to that “it has been proposed that the primary protective effect of the slime is related to impairment of the function of a predator fish’s gills.”
The Wikipedia article on hagfish is not very good.
GCM
It’s mucus, and has no particular taste. Yes, I’ve tasted it.
Wonderful experiment! Have you published on it?
GCM
I would never have guessed that the slime was used in such reactive and active ways!
I forgot:
I noted something odd to me. Some of those predators were pretty large, indicating age. But those unlucky encounters seem pretty memorable.
Is it a selection effect on the video encounters, assuming hagfish aren’t all that rare? I.e. do most fish simply ignore them because they learn that it is unproductive to attack them, and we are seeing a few individuals that haven’t tried before?
Get you diving gear & a research grant Torbjorn!
I saw this a few weeks back. What amazes me is the speed of the slime. Do we know the chemical composition of it?
It’s not really as fast as it seems. The vast majority of the slime comes directly from the surrounding seawater. The hagfish basically secretes a small quantity of protein which traps a much larger quantity of water.
The coolest thing, in my opinion, is that it literally ties itself into a knot, and uses it to clean the slime off itself (so it doesn’t suffocate along with the thing that tried to eat it).
Ta!
HERE’S a lot of interesting information about Hagfish slime including a short video where a glass of water is turned totally into a blob of slime by the addition of a small amount of the active ingredient. Fun to watch from a distance (like a lot of nature!)
Hagfish Slime is the new Spiderweb Silk:
The go-to-guy on hagfish slime is Dr. Doug Fudge go look at the Fudge Lab ~ lots of resources for slime fans
wow–I hadn’t known that.
The Hagfish Sliming Video I mention above [1 minute]
Great links– thanks Michael!
GCM
Fudge!
Thanks.
I love that in the second video they have a jar labelled “hagfish slime”.
hmmm…Wish I had known about that paper before a recent argument on the subject.
All of their evidence for cyclostome monophyly is from miRNA. I don’t know enough about miRNA evolution (does anybody, yet?) to accept this single paper as definitive. The chief piece of evidence (granted not the only) seems to be 4 miRNAs that are shared by hagfish and lampreys but not found in gnathostomes, but miRNAs seem to be very commonly lost.
THe story was much better the old way!
See my new post on hagfish for a bit more on this.
GCM
I do not like slime.
Then avoid burial at sea.
See Steve at 12. below…
The common laboratory frog Xenopus leavis (South African Clawed Frog)does something very similar when you handle it, but not with that volume.
You get copious amounts of slime from a Hagfish, and the slime sticks to everything. Made dissecting Hagfishes an interesting affair, wrestling with a wet soap describes it pretty well.
And then we had to clean the lab….
Send Greg the pictures!
If I can find them in the blackhole that is known as my study I might do that.
If you have the Hagfishes in a bucket the water in the bucket will very quickly turn into something akin to jello. It was amazing.
From a fundamentalist point of view: How lovely and intelligent of God to have the foresight to create slime.
I’ve visited during feeding time at the Vancouver Aquarium’s hagfish tank. After the hagfish ripped through the rotting corpse of their meal and one stuck its mouth out from inside the corpse’s anus, the guide dryly remarked, “Sort of takes the romance out of being buried at sea.”
I bet they still use that line.
Heard that one before!