The researchers report the study of a giant taret (Teredinidae) which is a mollusc that is reputed to tackle the woods of ships hence theirShipworm name .
From the myth of a monster to reality
People have known the existence of this giant taret for centuries . We have a first documentation dating from the 18th century which describes an animal of 1.5 meters. Their shells are quite common according to Daniel Distel , a research professor at Northeastern University . But we had never been able to study a living specimen .
The preferred habitat of this giant shipworm was unknown, but the research team benefited from a bit of serendipity when one of their collaborators shared a documentary that went on a TV channel in the Philippines. The video showed odd creatures planted like carrots in the mud of a shallow lagoon. Following their idea, the scientists mounted an expedition to study the living specimens of Kuphus polythalamia .
With a giant tint in their hands, the team cleared the mud that covered the outside of this giant worm and they broke the shell to reveal the creature that lived in it. The researchers were surprised by the size of the animal since the mollusks as well as the tarets have a dimension ranging from 1 to 60 centimeters. This taret has a way of life different from most other species.
Mud as main food
And the particularity of this giant taret is based on its habitat which is a lagoon with rotten wood. The natural giant shipworm is encrusted in the wood of the trees that pour into the ocean and they chew and digest the wood with the help of bacteria. Unlike his cousins, the Kuphus lives in mud, but he uses bacteria differently to feed.
The Kuphus lives in a particularly smelly place. The slime rich in organic matter from its habitat emits hydrogen sulphide which has a rotten egg odor. This environment is toxic to humans, but it is a treat for this giant taret. Moreover, this giant shipworm does not eat much because it counts on the bacteria on its gills to prepare its food. These bacteria use hydrogen sulphide as energy to produce organic carbon that feeds the taret. The process is similar to plants that use the sun’s energy to convert carbon dioxide into the air into simple carbon components during photosynthesis. And the result is that many digestive organs of this taret have shrunk, as it does not use them.
The way of life of this giant shipworm supports a hypothesis defended by Distel 2 decades ago. Acquiring beneficial bacteria could explain the transition on how tarets have gone from organisms with a normal diet to using a harmful gas in the mud to survive. Other differences between this giant taret and normal species will have to be determined.