Mollusks and Their Classification

What distinguishes mollusks from annelids in terms of physical features?

• Presence of a segmented body

• Distinct head and foot

• Lack of a coiled elementary canal

• Absence of gills

Where are the gills located in mollusks?

• In the mantle cavity

• In the visceral mass

• In the foot

• In the shell

Which system in mollusks includes a dorsal heart and a few blood vessels?

• Nervous system

• Respiratory system

• Circulatory system

• Excretory system

Which class of mollusks includes snails and slugs?

• Cephalopoda

• Gastropoda

• Pelecypoda

• Annelida

What is a characteristic feature of the class Cephalopoda?

• They are primarily terrestrial

• They have a spiral-shaped shell

• They have a well-developed nervous system and sense organs

• They are typically burrowers in mud and sand