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Eats wood and plankton
Wood contains cellulose that is composed
of a great many sugar molecules. With the help of bacteria, the ships
worm can split the cellulose and use it as food. Living on just sugar
is difficult, so the ships worm filters
plankton out of the water. Via the inhalent
siphon, that sticks out through a little hole in the wood, it is able
to suck in water that contains oxygen and plankton. The ships worm eats
plankton in much the same way as the blue
mussel.
The ships worm has the ability to draw in its siphons and
close the hole with its two palets.
Enclosed in this manner the ships worm can survive a period, even if its
habitat is washed up onto a beach or finds itself in freshwater.
Fertilization in the sea or in the exhalent
siphon
Methods of fertilization vary between
the different specie. With certain specie fertilization takes place externally
when the male and female release their sperms and eggs into the water,
very much like the life
cycle of the mussel.
With certain other specie the male releases its sperm into the water,
while the female keeps her eggs in the canal that leads to the exhalent
siphon. For fertilization to take place, the female has to suck in
the sperms via her inhalent siphon. This life cycle resembles the oysters.
The ships worm resembles the oyster in another way by the fact that it
can change between the sexes. When the larvae are mature they try to find
a shady place, and if the foundation is of wood they will stay and transform
into small worms and bore into the wood. The end of the worm where the
siphons are situated holds the pallets
and these are not moved during the whole of the mussels life. When the
mussel starts growing, it bores the other end into the wood.
Ships worms are found globally, but because they cannot
survive in brackish water, many well preserved wrecks can be found for
example in the Baltic, even if they have lied there several hundred years.
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