Bivalves
The bivalves are a very common group of molluscs- everybody
has generally come into contact with the humble mussel (of which
there are several species), whether on a restaurant table or
a rocky shore. Other examples of bivalves commonly found around
our coastline are the pipi (Paphies australis), tuatua
(Paphies subtriangulata), scallop (Pecten novaezelandiae)
and cockle (Austrovenus stutchburyi).
Bivalves are so-named because they have two shells that the
animal lives between. These ‘valves’ are hinged
together so that the animal can open up to water currents, food
and oxygen, or close up to avoid desiccation or predation. Bivalves
feed by filtering the water for plankton, which is sieved out
with their gills.
Did
you know?
Some bivalves are fixed to their substrate permanently with
byssal threads (mussel), others live within the substrate and
bury themselves using their muscular foot (pipi) and a few are
free living and can actually swim (scallop)!
