Gastropods - Yellow Cellar Slug
I found this Pacific Banana Slug on a tree one day in November 2014.
Slugs have a pneumostome, or a breathing pore, that opens into a lung cavity. Here the pneumostome is open.
And here the pneumostome is closed.
There is only one pneumostome and it is on the right side of the slug.
Pacific Banana Slugs produce two types of mucus, one thin and one thick and sticky. The thick mucus helps the slug cling to vertical surfaces and leaves these slime trails.