Threatening behavior by predators causes a porcupine to extend its quills.
Puffers are smooth skinned while porcupines have the characteristic spines or quills.
A porcupine will extend its spines when threatened.
What does a porcupine do with its spines when it's threatened?
(1) killing insects
(2) Shoot them
(3) kill them
(4) protect them
(5) Extend them
(6) Shed them
(7) Retract them
(8) behave