Allogona Townsendiana

Day 163: You really have to be careful where you step when you're walking the South Swofford Trail. It is home to a large population of Allogona townsendiana, aka the Oregon Forest Snail. Measuring roughly an inch across, these helpful little critters are serious players in the decomposition cycle of the Pacific Northwest's moist woodlands, gobbling up leaf litter and other forest debris, breaking it down in their digestive systems and releasing it again in a form which adds essential nutrients to the soil. It may not be Nature's most prestigious job opportunity, but somebody's got to do it. Thanks, Allogona!

Toothless

Day 166: We have quite a few species of snail in the Pacific Northwest and among the most common is Allogona townsendiana, the Oregon Forest Snail. The shell is brown and marked with thin, light lines when these snails are young, but the colour is only a papery layer which peels off in age, revealing a blue-white base. That said, Allogona can be confused with other species in age, and the most definitive feature for field identification is the absence of a tooth-like structure in the aperture. The Oregon Forest Snail is quite toothless!

Walks With Snails

Day 210: Between trying to avoid stepping on snails and keeping my arms away from the nettles, my walk on the South Swofford Trail yesterday was quite an adventure. The snails were as abundant as I've ever seen them, and new to me was what I took to be a black-bodied version of the common Oregon Forest Snail (Allogona townsendiana). After doing a little research, I believe it is a different species entirely, the Puget Oregonian (Cryptomastix devia). C. devia is reported to be abundant in the Cowlitz River drainage, i.e., where these specimens were found. The Pygmy Oregonian (C. germana) is a similar snail, but smaller.

Like many snails, these species are hermaphroditic. Some are self-fertile, which is to say they are capable of reproduction on their own in the absence of a mate. The bottom photo shows three snails (Allogona townsendiana) engaged in laying eggs on rotting hardwood.

Share The Trail

Day 173: You really have to mind where you step on the South Swofford Trail. I know of no other location where the Oregon Forest Snail (Allogona townsendiana) is so numerous. Perhaps its popularity with this species can be attributed to the trail's shady, moist environment. It is south of the lake, but north of a ridge, and stays dark and cool even in summer. That said, the OFSes are more plentiful in the months of autumn. I was surprised to see several munching the mulch on my walk today.

Trail Companion

Day 155: Watch where you step! With warming temperatures, all sorts of little critters are coming out of hiding and may be making their way across the trails. During my walks this week, I've found angleworms, a Woolly Bear caterpillar and an abundance of snails hiding among forest detritus, and I've heard our Pacific Tree Frogs singing although I haven't been able to spot any of them. These tiny folk can't get out of your way quickly, so it's up to you to be on the lookout. You don't want to hear the crunch of someone's shell under your foot, so please be careful where you tread.