Scientists find giant, elusive shipworm
Wednesday, 19 April 2017
When scientists found the giant shipworm after 250 years of searching, they may for a fleeting instant have wished they hadn't bothered.
The mollusc, which can grow as tall as a 12-year-old child and appears to survive without eating, is difficult to love. The giant shipworm, described in the journal Proceedings of the Natural Academy of Sciences, may be one of the laziest creatures on Earth. Analysis shows that instead of consuming its own food it appears to rely entirely on bacteria to do something a little like photosynthesis in leaves.
The eggy-smelling hydrogen sulphide gas emitted by plant matter as it decomposes under water nourishes microbes that live inside Kuphus, which use it in a series of chemical reactions that feed their host complex carbon compounds.
As a result the worm's digestive system seems to have withered away down the generations until it is as vestigial as the human appendix.
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Kuphus polythalamia, the largest member of the mussel and clam family, has been known since the 18th century from the 1 metre to 1.5m tubular hollows it leaves in the seabed and rotting timber.
Up to now, however, marine biologists have not been able to get their hands on a living specimen.
This changed when an academic happened upon a Philippine television documentary that showed the animals planted in the floor of a muddy lagoon like root vegetables.
'I was awestruck when I first saw the sheer immensity of this bizarre animal,' Marvin Altamia, a marine scientist at the University of the Philippines who worked on the find, said.
DNA suggested that it was once much like the other, much smaller shipworm species, which use bacteria in their mouths to wear down wood until they can process its nutrients.
'Being present for the first encounter with an animal like this is the closest I will ever get to being a 19th-century naturalist,' Margo Haygood, professor of medical chemistry at the University of Utah and one of the paper's authors, said.