Excerpts from Jim Conrad's
from the May 10, 2009 Newsletter, issued from the Siskiyou Mountains west of Grants Pass, Oregon:
A REALLY BIG SLUG
Usually when Anita comes to my trailer bearing a container it contains something good to eat. However, Wednesday at dusk just after another rain what she had in her little bowl was something else, shown above.
That's a pretty big slug. At first I thought it was completely black but the next day in better light I saw traces of spotting on it, and I had to agree with Karen's assessment that it was the Great Gray Slug, LIMAX MAXIMUS. I've seen a lot of Limax maximus in rainy Europe. In England it's often called the Tiger Slug or Spotted Leopard Slug because usually it can be described as having a yellowish body heavily marked with black spots. Apparently ours is "melanistic," which means that it is so heavily pigmented that its spotting is obscured. In the picture you can see spots near the rear end.
If Superglue didn't already exist I'd suggest that someone look into the mucous created by this slug, for it stuck to my fingers more than any animal product I've ever experienced.
The picture shows very clearly a kind of sharp keel running along the critter's top. The family the genus Limax belongs to is the Limacidae, known as the Keeled Slug Family, so this is a good field mark for slugs in that family.
Limax maximus can grow up to eight inches (20 cm) long. Usually they're nocturnal, though when it's rainy they can appear almost anytime. They feed mostly on rotting plant material and fungi. There's a lot of information on this species' anatomy and reproduction at http://webs.lander.edu/rsfox/invertebrates/limax.html.