EPOW - Ecology Picture of the Week

Banana Slug (Ariolimax columbianus)
Class Gastropoda, Order Stylommatophora, Family Arionidae
West Coast, United States

Explanation:  Ranging widely along the Pacific Coast of North America, from Alaska to California, is the humble banana slug.  

Here are just a few examples of their amazing color variants.  

The first photo is from Olympic National Forest on the Olympic Peninsula in northwestern Washington state.  This individual is uniform brown.

The second photo is from the seaside village of Gearhart of north coastal Oregon.  This one is brown with black spots.

And the third photo is from Prairie Creek Redwoods State Park in north coastal California.  This one is strikingly, well, banana colored.  

Other color variations include dark green and nearly white.  Some sources suggest that their colors vary with their diet and degree of moisture, and that color changes might serve a purpose of blending with their environment and hiding from predators, which include raccoons, ducks, snakes, and other animals.

As slow and unassuming as they are, banana slugs actually play some key ecological roles in their forest environments.  They consume and decompose plant material, and they disperse spores of fungi and seeds of plants, and distribute a rich nitrogenous fertilizer while doing so.  At times they may eat fruits and disperse fruit seeds and aid in distributing and regenerating forest fruiting plants. 

Banana slugs, like other slugs, crawl about on a muscular-foot and breath through an opening, called a pneumosone, on their side, as seen in this photo on the right.