Hey Polychaetes, Let’s Play the Silence Game Till the Next Whale-Fall, Okay?


In her recently-published dissertation for the University of Gothenburg, Swedish doctoral researcher, Helena Wiklund, identifies nine new species from two families of polychaete worms (Ophryotrocha and Vigtorniella) found on whale remains in Scandinavian and Californian waters. Polychaetes, a common type of marine annelid (or segmented worm), are found extensively across the ocean floor, and can be free-living grazers or attached to other organisms. All but one of the particular species Wiklund has concentrated on are free-living grazer worms who are adapted to the very specific habitat of a whale-fall, feeding off the bacteria that form filamentous mats over the surface of decomposing whale bones.

When whales die and sink to the ocean floor they provide a vast amount of food for a variety of marine life. The decomposition of a whale carcass takes place over three stages which involve specific types of organisms attending to different parts of the carcass. The initial stage of decomposition involves the larger flesh-eating organisms such as hagfish, sleeper sharks, and crustaceans, who pick the decaying flesh away from the skeleton. The second stage involves great numbers of macrofauna, like these newly-discovered and highly-specialised species of 2-centimetre-long polychaetes, gathering in the sediment that falls on and covers the bones, and the final stage sees the polychaetes feeding off the bacterial mats that form across the surface of the bones.

What Wiklund has also discovered is these species of bacterial mat-dependant polychaetes can also survive on sunken wood and beneath man-made fish farms, both the kinds of environments where concentrated amounts of nutrient-rich sediments can settle into these bacterial mats.

While whale-falls can feed many generations of polychaetes over several decades, they are few and far between, and just how the worms are able to travel from one carcass to another has posed a bit of a challenge to Wiklund. The Ophryotrocha larvae develop very quickly, the juveniles reaching adult form within days of hatching, making long-distance dispersal unlikely, as they can’t spend months traveling on ocean currents to the next whale-fall without the proper nutrients. However the Vigtorniella species have long-living larvae which can take up to nine months to reach adult form, and thus long-distance dispersal is a possibility.

Ophryotrocha scutellus worm

Now I can totally hear a bunch of migratory birds being like, “So the Vigtorniella larvae travel long distances. Whatever! We do that all the time, but are people always discussing how awesome that is? No!” And of course, they’re right, but we do have to be mindful of the fact that these are kids – or larvae, if you prefer – who are traveling long distances together, and that they make it to the next whale carcass at all makes it absolutely worth mentioning. I’m not suggesting that things are likely to decline into a sort of Lord of the Flies-like bloodbath, but it’s not like there are any adults around to be like, “Stop hitting your sister!” and “Didn’t I tell you to go before we left? We’re not stopping for another half an hour, so you’re just going to have to hold it in!”

Like, the journey would probably start out okay, the larvae all excited about finding a new stash of delicious whale bones to supply them with a multitude of breakfasts, lunches, and dinners, and for a while barely a word would be exchanged between any of them because they’re all too busy playing Petz or Lego Batman or something on their DS. But whale-falls are pretty rare and while the DS battery life is alright, it certainly isn’t going to last an entire trip, and you just know that someone will have forgotten to recharge theirs the night before. So one of the larvae will suddenly be like, “UGH!” pointedly slamming her DS shut so that everyone close by will hear her, and she’ll find one of her sisters and be all, “Hey, so my DS just died. Can I have a go of yours quickly?”

And her sister will be like, “Umm no way. I don’t want you using up all my battery life too.”

“But mum said we have to share!”

“Mum said to charge yours before we left.”

“I HATE you!”

“I hated you FIRST!”

And that’s just on the first day. Pretty soon it will degenerate into something along the lines of:

“I’m BORED. My pygidium hurts, and I need to go to the bathroom REAL BAD.”

“OH MY GOD… now I have to go!

“Ugh. Prudence, will you please tell Alex that it’s not my fault that she needs to pee and maybe she should stop trying to copy everything I do, and yes I’m still not talking to her because of that thing she said about how I always snort when I laugh which is so. not. true, because I know what I sound like and I don’t sound like someone who snorts when they laugh.”

“FINE. Umm Prudence, can you please tell Jessica that I said, “No offense,” before I said the thing about snorting, and Jessica said, “Okay.” So it’s not my fault she got offended when she already promised she wouldn’t get offended before I even said it.”

“Prudence, will you please tell Alex that just because she said, “No offense,” it doesn’t mean she can just say whatever she wants, like, I bet she wouldn’t like it if I said, “Hey, Jessica, no offense, but your chaetae are looking pretty thin. Maybe it’s because you’re underdeveloped…?” would she?”

“Prudence, will you please tell Jessica that actually I am allowed to be offended by that because I didn’t actually say, “Okay,” to the “No offense,” and– Wait, what do you mean my chaetae are thin? As if they are and at least my bristles aren’t too short like yours are!”

And somehow they manage to ride the ocean currents across extensive distances without pulling each other’s segments apart. I know I’m impressed.

Original Dissertion (open access) // Paper in Zoological Journal of the Linnean Society // Pictures courtesy of Helena Wiklund.

– bec


Filed under New Species!, Science, Sea Creatures

2 responses to “Hey Polychaetes, Let’s Play the Silence Game Till the Next Whale-Fall, Okay?

  1. “Whalefall” is one of the coolest terms ever…

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