Cornucopia

One, two, three, four, five, six.  "Cornucopia" is the collective noun for slugs.  I had to look this word up since I had never seen slugs in a group.  In fact, during all the treks I have taken in the woods, over all the years, I have never seen anything quite like this.

One week ago, I was in the newly opened Kukutali Preserve which comprises Kiket and Flagstaff Islands in Skagit Bay.  Near the west end of the South Trail is a heap of fallen trees, rotten wood and bark.  It appears to be windfall that was cut up and piled next to the trail.  The stuff was swarming with Banana Slugs (Ariolimax columbianus).  Most seemed to be resting with their antennae pulled in under their mantles.

Banana Slugs are familiar forest denizens in the Pacific Northwest.  What we usually see are solitary individuals here and there along a trail.  There might be one or two of these reclusive creatures seen on a hike.  If it has rained overnight, we could see several the next morning.  They will be spaced out along the trail, going about their sluggy business recycling 11% of the forest biomass every year.

Searching the net, I was not able to find a specific reason for such an aggregation.  I can only venture a guess.  I think the gathering might have had something to do with slug reproduction.

Slugs are hermaphroditic which means that each individual is both male and female.  Every slug is equipped to produce both eggs and sperm.  Mating is usually a mutual affair, each partner inseminating the other.  There didn't appear to be any of that going on during my visit.  What I may have stumbled upon was the aftermath following a night of courtship.

Slugs find mating partners with pheromones broadcast in their slime trails.  These are chemical signals that call in the troops, so to speak.  That may explain why there were so many grouped together.  It stands to reason that such an aggregation of individuals would increase reproductive success.

Finally, there's that apophallation thing.  After mating, the pair is sometimes unable to separate.  They resort to chewing off their own or their partner's penis to make separation possible.  Too much information, I know, but never fear.  The altered Banana Slug will continue a happy life as female.  And I am sure we'd all need to take a rest after that experience.



The next question I had was why they were congregated around all this rotted wood.  I found one reference that indicated they like to lay their eggs in rotted wood or bark.  This will insure the eggs will stay constantly moist.

When I returned to the Kukutali site last Friday, only about half of the group remained.  On today's visit, all of this cornucopia of slugs was gone.  I was again seeing only single individuals here and there along the trails.  I wonder if I will ever see such a spectacle again.

As usual, I would enjoy hearing from anyone who has information about why these slugs had gathered together like this.

If you go down to the woods today
You're sure of a big surprise.
If you go down to the woods today
You'd better go in disguise!

For ev'ry slug that ever there was
Will gather there for certain, because
Today's the day
Banana Slugs have their picnic.

If you go down to the woods today,
You'd better not go alone!
It's lovely down in the woods today,
But safer to stay at home!

For ev'ry slug that ever there was
Will gather there for certain, because
Today's the day
Banana Slugs have their picnic.

With appreciation to all Teddy Bears and Jimmy Kennedy