Today.Az » Weird / Interesting » 'Zombie' worms found in mediterranean fossil
03 November 2011 [12:48] - Today.Az
Traces of bizarre, bone-eating 'zombie' worms have been found on a
3-million-year-old fossil whale bone from Tuscany in Italy. It is the
first time the genus Osedax has been found in the Mediterranean, and
suggests Osedax were widespread throughout the world's oceans 6 million
years ago.
The new find, published in the journal Historical Biology,
confirms what scientists have long suspected -- that Osedax were likely
responsible for erasing parts of the fossil record by destroying bones
before they could become fossils.
Worms from the Osedax genus do not have a mouth or gut but consume
the bone by growing root-like tissues, which dissolve the bone as they
grow.
Lead scientist Nicholas Higgs discovered tell-tale traces of Osedax
in the Mediterranean last year using micro-CT (Computed Tomography)
scanning technology as part of his PhD at the University of Leeds and
the Natural History Museum.
He says: "After several promising leads came to a dead end, the scans
from the final sample looked different and I knew that I was on to
something."
Osedax were first discovered alive in 2002 in Monterey Bay,
California, where they were living on the bones of a decaying gray
whale.
Since then, scientists have been curious about how the worms might
have affected fossil records, but understanding when Osedax evolved and
where they lived in the past has until now remained a problem because
actual remains of soft-bodied Osedax do not preserve as fossils.
The only way to tell where and when Osedax have been at work is by
distinctive bulb-shaped cavities that they leave behind in a bone -- and
it is these borings that have finally been recognised by Higgs.
His research shows how widespread Osedax were millions of years ago.
The only other known evidence of Osedax from the past is in whale
bones from the Pacific coast of Washington State in the US -- about as
far away as it is possible to get from the Mediterranean in terms of
ocean connectedness.
When Mediterranean dried up almost six million years ago most deep
sea animals were killed. About half a million years later the sea
re-flooded from the Atlantic.
Higgs says: "So finding out that Osedax were feeding on this whale
bone three million years ago tell us that their ancestors must have also
been living in the Atlantic as well, because the Mediterranean was
re-colonised 5.5 million years ago from the Atlantic."
It is now almost certain that the Mediterranean is currently host to undiscovered, living Osedax species, Higgs says.
"There are 20 different species in Monterey, California alone, so
it's almost certain there are many more out there. If Osedax were living
the Mediterranean three million years ago there's no reason why they
aren't living there now."
Last year, Higgs travelled to California to examine living Osedax and
their borings to help understand and identify the full range of known
species. /Science Daily/
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