Describing the Filter Feeding of Invertebrates Such as Mussels
This essay will be analysing the occurrence of filter feeding and
demonstrating it as a unique adaptation for marine mammals. It will
also analyse how filter feeding, combined with invertebrates such as
mussels, produces a complex, yet distinctive foraging strategy. This
essay will also discuss the features of molluscs and how they are
adapted to use their features to aid their particular means of
feeding, including the full process of how this form of consumption
An important necessity for any organism is ...view middle of the document...
They travel through the siphon. When
passing through, the mucus, on the gills of the invertebrate, traps
the passing particles. The particles and the water current are then
transported by the cilia along a food groove and towards the mouth.
Once entering the intestine, enzymes begin to break down food
particles, leaving the carbohydrates to be absorbed as monomers.
Many bivalve molluscs (two hinged shell invertebrates), feed on
particles in the surrounding water. One example of a mussel that does
this is Mytilus edilis. They live in the interitidal zone, and attach
themselves firmly to rock pilings or any solid surfaces. They achieve
this by secreting threads from the muscular foot; the threads are
called bysusses and prevent the mussel from being able to move around
in the water, unlike other molluscs.
When the mussel is covered in seawater, the two-hinged shells open up
slightly and allow water to enter the body of the mollusc. However,
when the tide is out, its shell protects the body. After this occurs,
the mollusc extends two short tubes, also known as siphons. Then,
through one opening, a current of water is drawn in. It travels across
the gills and out through another opening. A filter feeder creates a
feeding current by the cilia beating or moving rhythmically. This
whole movement arises by the combined effect of these hair- like
projections, which line the spaces within the mussel's shell.
The system of foreign particles being trapped in the body of the
mussel and then digested is very similar to the process in humans. The
cilium within a mollusc traps the foreign particles, including
bacteria, and then takes them to the stomach to be digested. Except,
the cilia are on the filaments of the mussel, and they also send a
current of mucus down each strand and then towards the mouth. The
gills on a mollusc hang downwards and trap the small particles,
including the extraction of dissolved oxygen from the water. As long
as the particles are a suitable size, they will be digested.
Zebra mussels are also filter feeders. When filter feeding, the water
passes through the gills via a small opening called an ostia. Oxygen
is also exchanged across the gills and into the blood, where it can be
transported throughout the mussel. Unlike freshwater mussels that
burrow in sediment zebra mussels also attach themselves to hard
surfaces, such as barnacles. A single zebra mussel can filter up to a