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.
