A hydrothermal worm, but of what species? (Image: FEI)
The microscope maker FEI posted this scanning electron micrograph in its image gallery with only the label “hydrothermal worm.” (And thanks, while I’m at it, to Rob Beschizza of Boing Boing and JWZ for bringing it to my attention.) Unfortunately, that labeling leaves much to be desired because the description “hydrothermal worm” fits a great many wee beasties.
—And here, this post veers into a different direction than I’d first intended. You see, with the identity of the worm uncertain, I was about to challenge the hivemind of all of you to try to name the species to which our toothy friend belongs. For reasons that I’ll soon explain (*cough*Carl Zimmer*cough), that challenge is now unnecessary.
I would have pointed out that this hydrothermal vent worm was probably some form of polychaete—but that even if so, that assumption left no shortage of possibilities because the polychaetes (a.k.a., bristle worms) are an exceptionally large and diverse class encompassing more than 10,000 known species. My first hopeful guess was that this worm might belong to the genus Nereis, which is a particularly well-studied variety of polychaete, some of which (for all I knew) might live around hydrothermals. And that group includes a species with a face like this, about which we can reasonably ask, what the hell?
Scanning electron micrograph of Nereis. (Credit: Daniel Desbruyeres, lfremer, via BP Kongsberg Underwater Image Competition 2006.)
But the mystery specimen couldn’t be Nereis because worms in that genus seem to have pincer jaws rather than a toothy beak. 
Pompeii worm (Alvinella pompejana), head at bottom left. (Credit: University of Delaware)
The toothy mystery worm ought to have a truly menacing nature, which is why I also fleetingly hoped it would be a Bobbit worm (Eunice aphroditois). Consider this description of the Bobbit worm from Wikipedia (emphasis added):
Eunice aphroditois, the Bobbit worm, is an aquatic predatory polychaete worm dwelling at the ocean floor at depths of approximately 10 metres (33 ft) to 40 metres (130 ft)….
Armed with sharp teeth, it is known to attack with such speeds that its prey is sometimes sliced in half. Although the worm hunts for food, it is omnivorous. … [T]hese worms can grow to sizes of nearly 3 metres (9.8 ft) in some cases (although most observations point to a much lower average of 1 metre (3 ft 3 in)) and 25 millimetres (0.98 in) in diameter. A long lifespan may very well explain the size of these creatures….
In March 2009, the Newquay’s Blue Reef Aquarium in Cornwall UK, discovered a bobbit worm in one of their tanks. The workers had seen the devastation caused by the worm, such as fish being injured or disappearing and coral being sliced in half, but didn’t find it until they started taking the display apart in the tank.
Nice. That’s a worm with gratifyingly homicidal tendencies. (I can neither confirm nor deny that it is named after Lorena and John Wayne Bobbit and their legendary penis-severing tabloid adventure—but I really hope it is.) Alas, once again, as you can see from this picture of a Bobbit worm, its mouthparts bear no resemblance to those we seek. And if the jaws don’t fit, we must acquit.
The terrifying Bobbit worm, Eunice aphroditois. It only gets 9 feet long and slices its prey in half. Sleep well, little children! (Credit: Jenny, via Flickr and Wikipedia)All my speculations would have probably ended there. But we’ll never know whether any of you would have come up with the answer because while I was writing this post—bam!—the bio-omniscient Carl Zimmer identified it all by himself on his Tumblr account: it’s Lepidonotopodium piscesae Pettibone, first identified in 1988. (Yes, I know: that was going to be your first guess, too.)
Lepidonotopodium piscesae Pettibone, 1988. (Credit: lfremer, via LifeDesks)LifeDesks has a gallery of shots of this worm, and if one sees the whole creature and not just its menacing mouth, as in the picture at right, it looks rather more cuddly than carnivorous. This type of Lepidonotopodium crawls on the seafloor near the vents and uses those teeth to munch on mats of bacteria and protozoa it finds there. The worm seems to be distributed across the Juan de Fuca Ridge, off the coast of Washington state and British Columbia, and according to at least one paper from 1999, it seems to be adept at surviving in extreme conditions there.
But even if it has lost some of its fearsomeness, it is still an intriguing creature. See the white hairs protruding in clumps from between the scales on its back? They aren’t hairs; they aren’t even technically part of the animal. They are filaments extending from symbiotic bacteria that live among the scales. It seems that like the Pompeii worms and many other organisms that live at hydrothermal vents, Lepidonotopodium depends on bacteria to survive, though it seems to be unclear whether the bacteria are providing nutrients to the worms or providing some other service.
In summary: Carl Zimmer made this post unnecessary and ruined all our fun, and the saw-toothed worm that inspired it turns out to be rather more gentle than I’d hoped. However, in case anyone is tempted to dismiss the threat of hungry polychaetes, remember the Bobbit worm and consider this recent news story, as reported in the Herald Sun:
Horror as tiny worms with teeth attack Victorian couple
A VICTORIAN couple endured a health nightmare after tiny worms with teeth began eating through their bodies.
It is the first time humans have been infected by the parasite in Australia.
It is believed the couple became ill after eating a fish they caught on a WA camping holiday.
Alfred hospital infectious disease physician Andrew Fuller said that when the couple ate the fish, believed to be a black bream, they also ingested the gnathostomiasis larvae.
“The worms are 1-3mm long and have got these sharp little teeth and they can go anywhere they like in the body,” Dr Fuller said.
The worm works its way around the human body until it dies or is killed by the immune system.
And what do the mouthparts of Gnathostoma larvae look like?
Gnathostoma larva. (Credit: Pichart Uparanukraw, Department of Parasitology, Faculty of Medicine, Chiang Mai University, Thailand, via the CDC)Nasty. (Update: Or should I say gnasty?)
Reference:
“Physical and chemical factors influencing species distributions on hydrothermal sulfide edifices of the Juan de Fuca Ridge, northeast Pacific.” J. Sarrazin, S. K. Juniper, G. Massoth, P. Legendre. Marine Ecology Progress Series, vol. 190: 89-112 (1999). doi:10.3354/meps190089
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