The subsurface of False Bay is notable for its polychaete diversity. This diversity is well demonstrated by the variety of feeding strategies used by the different polychaete families, which display five distinct feeding strategies.
Many of the polychaete species found in this survey of
False Bay are burrowing worms that lead a more or less sedentary lifestyle
in a U or J shaped burrow. Specialized head feeding structures demonstrate
the variety of feeding methods these polychaetes use.
Subsurface deposit feeding: Aberinicola, commonly called "lugworms," live in a J-shaped burrow with the head facing away from the surface. This worm swallows sand and creates a current through the tube, and digesting food off of the sand particles. Little coiled piles of defecated sand can be seen at the openings of the burrows. Individuals belonging to this family were commonly found in the Lugworm area.
Another family, the Maldanidae, live in straight sand-grain
tubes, with their anterior end also facing away from the opening of the
tube. Much of the food that these worms eat is detritus that has settled
to the bottom during high tide (Rupert and Barnes 1996). This family was
commonly found in the eelgrass and Ulva
Surface deposit feeding: The family Terebellidae is a group of worms that are selective surface deposit feeding worms whose heads protrude from the surface and extend many spaghetti like tentacles that are covered in sticky mucous. Deposited detritus and sand particles stick to the tentacles and are moved toward the mouth by ciliary action. Cilia on the lip of the mouth force food into the mouth (Rupert and Barnes 1996). This family was frequently found in the Ulva area.
Carnivorous feeding: These worms feed on small invertebrates by using an eversible pharynx. The pharynx looks like a cylinder with jaws at the end and everts quite rapidly. Glycerid worms live in networks of subsurface tubes with openings to the surface. When these worms detect movement, they sneak up to the surface for a possible kill (Rupert and Barnes 1996). This family was frequently found in the Lugworm area.
Omnivorous/Herbivorous feeding: These polychaetes use their jaws to tear off pieces of algae, invertebrates and detritus. The abundant family Lumbrineridae feed this way (Rupert and Barnes 1996). This family was frequently found in the mud shrimp and lugworm areas.
Suspension feeding with mucous filter: The
family Chaetopteridae feed in an interesting way while living in U-shaped
tubes. The head of a chaetopterid points towards one of the openings.
The worm has modified appendages in the shape of paddles, which are
used to produce a water current that enters on the head end of the tube
and exits at the other end. A sheet of mucous near the head is secreted
into a bag-like form by another set of modified appendages in the shape
of wings. This mucous bag strains suspended detritus and plankton from
the water as it flows through the tube. When this bag reaches a certain
catch, it is ingested. Some Chaetopterids form vertical tubes instead of
U-shaped (Rupert and Barnes 1996). These are found in the sand
These carnivores feed mostly on polychaetes and crustaceans.
The feeding style of this carnivorous group is notable for the use of an
incredibly large proboscis that everts from the head region. This structure
is not connected to the digestive tract, but is rather attached to a specialized
cavity called a rhynchocoel. When muscles contract around the rynchocoel,
the proboscis is everted by hydrostatic pressure. A retractor muscle
is used to withdraw the proboscis back in to the rynchocoel. In many
species this proboscis is armed with a sharp tooth-like structure called
a stylet, which is used for stabbing prey. Some species can use the proboscis
as a noose to coil around and bisect prey, and sticky toxins may be secreted
from the proboscis in order to immobilize prey (Rupert and Barnes 1996).
This group was occasionally found in the Ulva
One class of mollusc, thebivalves, are usually filter feeders, but do obtain their food in an interesting fashion. The gills, normally used for respiration, are modified in many molluscs into a filtering structure for straining food particles out of suspension. Cilia on the gills are used to transport trapped food to the mouth. Unlike other Molluscs, bivalves lack the radula, a specialized belt of teeth that is used by other molluscs for grinding up food for digestion (Rupert and Barnes 1996). Bivalves were common throughout False Bay.
Gastropods found in the sediment of False Bay, primarily
the snail Lacuna, do have a radula and are herbivores. These small
snails may creep along the surface, scraping diatoms from eelgrass like
a vacuum cleaner, or graze on the abundant Ulva (Kozloff 1986).
Echinoderm (Leptosynapta clarki)
These small worm-like sea cucumbers use branched tentacles
located near their mouth for feeding. While burrowing in the sand, the
modified tube feet collect detritus from the sediment and transfer this
material to the mouth (Kozloff 1986). This species was common in all of
the sampled areas except for the lugworm area.
mud shrimp and ghost shrimp (Neotrypaea and Upogebia) found
burrowing in the mud of false bay actually filter feed from the water current.
These shrimp create large burrow networks with at least two openings to
the surface. They collect detritus from the mud through which they
burrow, collecting food particles on the hairs of their legs. One pair
of appendages scrape this off and transport the food to the mouth region.
Most of the feeding is done at high tide (Kozloff 1986). These two species
were common in the mud shrimp
More information on most of the species mentioned on this page can be found on the species description page.