Pacific Sideband Snail

Pacific Sideband Snail (photo Walter Siegmund)

Species: Pacific Sideband Snail – Monadenia fidelis

B.C. Status: Yellow  (apparently secure – not at risk of extinction)

Key Information:

This medium-sized land snail is unique to other snails in size and features. Pacific sideband snails have evolved their mantle cavity into a lung and breathe through a single opening on the right side of the body. This feature is unique to them; other snails have gills.

Pacific sideband snails can be found in among the leaf litter in cool, moist, shaded, mixed forests. These ecosystems provide them with ample camouflage, moisture, and food. Their diet consists of fungi and most any vegetation. They eat using what is called a radula; which is essentially their tongue and teeth. The radula scrapes and shreds food so it can be ingested. As well as food, leaf litter provides them with camouflage, helping to protect them from predators including snakes, raccoons, shrews or mice.

Like all snails, the pacific sideband is a hermaphrodite, which means they have both male and female reproductive organs. Upon sexual maturity, around 2 years, they mate with other pacific sideband snails enhancing genetic diversity. When they cross paths with another pacific sideband, they shoot “love darts” engaging in an elaborate courtship process, much like cupid. These “love darts” aid to enhance successful reproduction.

With their limited capability to travel, these snails are vulnerable to changes in their habitat. Ecosystem health and resilience is of utmost importance to them – decrease in rainfall and increase in wildfires, can weaken their ecosystem, and their habitat can become more susceptible to invasive plant species, which compete with their native food sources.

Habitat destruction/fragmentation is a major contributor to decreasing snail populations. Human activities such as logging, urban development, ATVing/biking – to name a few – all have a significant impact upon the pacific sideband snail population. Both indirect, through a change in habitat, as well as direct mortality.

Identification – what to look for:

• Shell is up to 35 mm in diameter
• Shell colour ranges from chestnut brown to dark rose
• Typically there is a dark band around the perimeter of their shell and some have a yellow band as well
• The shell has about 7 whorls with a thin black line along the bottom of each whorl
• Some island populations may have pale white shells with dark whorl lines
• The body of this snail is rosy-pink or pinkish-brown and quite wrinkled
• Two long delicate retractable tentacles on their forehead (this is where their eyes are found)
• Two shorter tentacles protrude either side of its mouth, which is where their nostrils are found

Where are they found?

• Along the Pacific Coast from Alaska to California
• Mixed forests
• On moist forest floors with plenty of leaf litter, fir needles, ferns, moss, etc.
• They can sometimes be found up in trees and at the base of bigleaf maple trees
• On Cortes Island, they have been recorded in Carrington Bay Regional Park, Whaletown Commons, and near the Freestore

Cool Facts!

• Largest native terrestrial land snail in British Columbia
• These snails are known to live up to six years!
• They hibernate in the winter months
• In dry summer months, they enter into a mild hibernation
• Adults dig nests in the leaf litter to deposit their eggs during the spring months
• Can be found up to 7 metres up a tree!

Useful Links:

http://www.sccp.ca/species-habitat/pacific-sideband

https://nisquallylandtrust.org/natures-cupid-the-pacific-sideband-snail/

https://ibis.geog.ubc.ca/biodiversity/factsheets/pdf/Allogona_townsendiana.pdf

https://www.inaturalist.org/taxa/62803-Monadenia-fidelis 

https://silverfallswordfromthewoods.wordpress.com/2013/03/17/pacific-sideband-snail-3/