Trailside Treasures:
Meet the Gastropods of Issaquah

 
 

The Unsung Heroes of the Forest Floor

Native gastropods in the Issaquah Alps are essential for nutrient recycling, seed dispersal, and supporting local wildlife. Slow-moving and moisture-dependent, they’re vulnerable to trail use and habitat disruption. Protecting these crucial creatures helps maintain the health of our local ecosystems

 
 
 

Forest Health Starts Small

Nutrient Cycling

  • Break down decaying leaves, fungi, and plant matter

  • Return nitrogen and minerals to the soil

  • Function like natural composters, slowly enriching the ground

Soil Aeration

  • Glide across the soil surface, gently stirring it

  • Improve airflow and water infiltration

  • Contribute to healthier root development

Seed Dispersal

  • Banana slugs help spread seeds of native berries & wild ginger

  • Aid in natural forest regeneration and plant diversity

Decomposition Support

  • Accelerate the breakdown of organic material

  • Contribute to the formation of humus

  • Support microbial communities vital to soil health

Complement Earthworms

  • Earthworms work deeper underground

  • Slugs and snails focus on the surface layer

  • Together, they build a multi-layered, dynamic soil ecosystem

 
 

Source: iNaturalist.

Every Step Has an Impact

Banana slugs and native snails often blend into the trail — their slow movement and natural camouflage make them easy to miss. Many are unintentionally stepped on or crushed. Unlike us, they cannot escape quickly or recover from injury.

A Fragile Existence

These species are already under pressure from habitat loss, climate change, invasive species, and trampling — even in protected areas like the Issaquah Alps.

Be Mindful on the Trail

  • Watch your step — slugs and snails cannot see or hear.

  • If you run, be extra cautious during busy trail hours.

  • If you find one in danger, gently move it to safety using a leaf.

 

Meet the Slugs & Snails of the Pacific Northwest

 
 
 

Nature Backed by Research

The Pacific banana slug, Ariolimax columbianus, is an iconic Pacific Northwest species that is an integral component of our beautiful local ecosystems. The activities of these slugs in our forests and parks are essential to maintaining healthy biodiversity and supporting other native animal and plant species. Banana slug sightings on trails are a big part of what makes walking and hiking in the Pacific Northwest a unique and rewarding experience! Although they can sometimes be mistaken for invasive pest slugs that damage gardens and agriculture, banana slugs are native to the Pacific Northwest and do no harm. In reciprocity, I pose that it is our responsibility to do what we can do to support banana slugs along park trails and encourage walkers and runners to avoid inadvertently causing their harm or death (for example, by accidentally stepping on them).

Dr. Dee Denver, PhD
Department Chair and Professor of Integrative Biology
Oregon State University

For more information, visit Gastropod Rescue Instagram.
© Iku Kageyama 2025