Feeding and Locomotion in Molluscs

What is the feeding method used by most gastropods?

They use a radula to scrape or cut food, such as algae or plant material.

How do carnivorous gastropods feed?

They use modified radulae to pierce, rasp, or inject toxins into prey like worms or other molluscs.

How do herbivorous gastropods use their radula?

They scrape algae or plant matter from surfaces with their radula.

How do cephalopods feed?

They are active predators using a beak to bite prey, often aided by tentacles and a radula.

How do bivalves obtain food?

Through suspension feeding using cilia on their gills to filter particles from water.

What is the feeding method of scaphopods?

They are deposit feeders using tentacle-like captacula to collect food particles from the sediment.

How do chitons feed?

They use a radula to scrape algae off rocks in intertidal zones.

What is a radula?

A chitinous ribbon-like structure with rows of teeth used by molluscs for feeding.

Where is the radula located?

In the buccal cavity, just in front of the oesophagus.

How does the radula function?

It moves back and forth over a cartilaginous structure (odontophore) to rasp or cut food.

What is the odontophore?

A supporting structure beneath the radula that helps move it during feeding.

What is the radula made of?

Chitin and often hardened with iron or silica in some species.

How is the radula used in herbivory?

It scrapes surfaces to collect algae or plant matter.

How is the radula used in carnivory?

It may have hooked or harpoon-like teeth to pierce prey or inject venom.

Give an example of a carnivorous gastropod using its radula.

Cone snails use a modified radula tooth to inject neurotoxins into prey.

What is suspension feeding?

A feeding strategy where organisms filter small food particles from water.

Which molluscs are primarily suspension feeders?

Bivalves such as mussels, clams, and oysters.

How does water flow over the gills in bivalves?

Inhalant currents bring water in; cilia on gills trap and move food particles to the mouth.

What are lateral cilia in bivalves?

Cilia that create water currents over the gill surface.

What are frontal cilia in bivalves?

Cilia that move trapped particles along the gill toward the mouth.

What are laterofrontal cilia in bivalves?

Cilia that help capture particles by creating eddies near the gill surface.

What happens to particles too large to ingest in bivalves?

They are sorted out and rejected as pseudofeces.

What structures do bivalves use to sort food?

Labial palps and specialized gill surfaces.

What is the function of the gastropod foot?

It enables crawling locomotion using muscular waves and mucus secretion.

How do gastropods move?

They contract muscles in the foot to produce pedal waves, aided by mucus to reduce friction.

What type of muscle contractions drive gastropod locomotion?

Pedal waves—alternating contraction and relaxation of longitudinal and transverse muscles.

How does mucus aid gastropod movement?

It reduces surface resistance and helps the foot glide smoothly over surfaces.

What adaptations exist in the foot of burrowing gastropods?

It is more muscular and may be wedge-shaped for pushing through sediment.

How do bivalves burrow?

They extend the foot into the substrate, anchor it by swelling, and then pull the body downward.

What part of the bivalve foot anchors it in the sediment?

The tip of the foot expands to grip sediment before pulling the body downward.

What type of movement helps bivalves burrow?

Hydraulic and muscular expansion of the foot, aided by shell valve movement.

Why is burrowing important for bivalves?

It provides protection from predators and environmental stress.