is one piece episode 18 filler?

While at sea, Luffy designs a jolly roger to represent the crew. After refining the design with his artistic skills, Usopp paints it to the sails.

However, Nami spots the Island of Rare Animals in the distance, an island rumoured to contain legendary treasures but is divinely protected by the gods. The crew decide to dock at the island to plunder its treasures.

However, they are quickly confronted by strange hybrid animals and an unseen man claiming to be a god. After his makeshift traps fail against the crew, he attempts to retreat, but the crew catch him.