Final answer:
Lateral canals in brittle stars are part of their water vascular system, allowing them to extend and retract their tube feet for movement and feeding.
Step-by-step explanation:
Lateral canals in brittle stars are part of their water vascular system. The water vascular system is a network of fluid-filled canals that helps in locomotion and feeding. In brittle stars, the lateral canals connect the tube feet on the arms to the radial canals in the central disk. This allows the brittle stars to extend and retract their tube feet, enabling them to move and capture prey.