Defensive strategies employed include the presence of spines, toxins, which can be inherent or delivered through the tube feet, and the discharge of sticky entangling threads by sea cucumbers. Being stabbed by a sea urchin may result in painful injury.
Its shell.
they are both invertebrates
the structures of defense can be their claws and sharp teeth
Mollusks have hard shells to help protect them.
nephridia
Mollusks have a mantle, which is a protective layer of tissue that covers their soft body. The mantle plays a role in shell formation and can also secrete mucus for locomotion or defense.
Stinging cells
many minds
It's neck
No ......mollusks are not segmented,like insects....just their body is partitioned into head, foot, and visceral hump..........but one can't take it as segmentation.........
Lionfish have poisonous spines.
it's hard shell