Mussels utilize fish during a crucial stage of their early life cycle to grow and disperse. This interaction is a fascinating part of how these sessile animals develop.
The Larval Stage and Fish Interaction
Unlike many animals, mussels have a larval stage that requires a temporary host. As detailed in a 2012 reference, female mussels employ a unique strategy to ensure their offspring's survival and spread:
- Larva Release: "When a fish strikes at the bait, the female mussel squirts her larva onto the fish's gills." This shows the specific mechanism triggered by the fish's presence or activity. The larva are often in a specialized form called glochidia.
- Attachment and Development: These mussel larva then attach themselves firmly to the gills (or sometimes fins) of the fish. While attached, they undergo a significant period of development. "Eventually, the larva develop into little mussels" during this parasitic stage on the fish. The fish essentially acts as a mobile nursery, providing a safe environment and aiding in dispersal to new locations.
Dropping Off and Settling
Once the larval mussels have completed their metamorphosis into juvenile, self-sufficient little mussels while on the fish host:
- The "little mussels... drop to the bottom of a river or lake".
- They then "burrow into the mud where they'll probably live for the rest of their lives". This marks the transition to their adult, bottom-dwelling lifestyle.
So, mussels don't 'fish' in the way humans do; rather, they use fish as a temporary host during their critical larval growth stage before settling down.
