Zombie Worms

Deep in the ocean members of the Osedax family are scraping a living from the bones of the dead, whether they are fish or mammals like whales. When we say bones we mean bones. They drill into the bones and extract any nutrient that’s left.

Davies for BBC Nature reports on this pretty clever trick this week (1), and it is a clever trick because these zombie worms have no mouth, let alone a GI tract. They’ve been around for a long time and have been doing well without the inconvenience of a GI tract, munching away quietly in depths of the ocean, but we have only been aware of them for the past ten years.

How does this worm work it’s magic?  At the business end, which attaches to the bone, I guess we could call it the head, but that might be going too far, there are lots of bumps that secrete acid that dissolves the calcium and gives the worm access to the lipids (the fats) in the bones.

 Sucking without a mouth or GI tract is not an option so the business end is where the transfer into the worm proper takes place aided by little bacterial farms, which the enterprising worm sets up to process the fats. The non-business end splits into feathery plumes that allow oxygen to diffuse into the body to keep things ticking over.

The next big question that I can hear in the distance is if it has one end buried in a bone and the other waving about in feathery splendor, how does it set about breeding, especially as it’s not mobile? Well, all the worms that you see are female and they carry a large harem of male worms inside their bodies. These harems are quite large consisting of 30 – 100 little male worms up to a millimeter long. They don’t get to share in the food though – they have to live off their yolk sac doing their duty as best they can.

With all these little males working hard, the egg production is also quite large and it’s just as well as the parent worm will die when the nutrient in the bone is exhausted, leaving it to the youngsters to go forth and colonize.

  1. http://www.bbc.co.uk/nature/18594493

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