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Photo of a Northern Horse Mussel

Species profile

Northern Horse Mussel

Modiolus modiolus

Clams/oysters/mussels2.4K iNat observations

At a glance

Northern Horse Mussel (Modiolus modiolus) is a bivalve mollusk present across the CatchRules coverage area but without species-specific bag, size, or season rules tracked in our regulatory dataset.

Confirmed by 1,817 research-grade iNaturalist observations, with Nova Scotia, Maine, and Massachusetts the top jurisdictions by observation count.

Notable details

  • Can grow to 20 cm (8 inches) — significantly larger than the familiar blue mussel.
  • Lives in cold waters on both sides of the North Atlantic and North Pacific.
  • Can survive over 25 years, far outliving most other mussel species.
  • Has a thick, fibrous outer shell coating called a periostracum that cushions it from wave impact.
  • Forms dense beds that provide shelter and habitat for hundreds of invertebrate species.

Where Northern Horse Mussel are seen

Background

Modiolus modiolus, common name northern horsemussel, is a species of marine bivalve mollusk in the family Mytilidae.

Background excerpt adapted from Wikipedia's Northern Horse Mussel article (CC BY-SA). Visit Wikipedia for the full entry.

Photo credit: iNaturalist / Wikipedia. Identification reference only — verify regulations with the issuing wildlife agency before retaining a catch.