1. a relationship between two organisms in which one lives on the external surface of the other without harming or benefiting it; commensalism involving external parasites or surface-dwelling organisms.
Usage: biology; ecology; formal

Examples

• The study of epizoism helps biologists understand how organisms coexist on shared surfaces.
• Epizoism is common in aquatic ecosystems where small creatures attach to larger animals.
• Unlike parasitism, epizoism does not typically cause harm to the host organism.
• Marine biologists observed epizoism when barnacles settled on whale skin without damaging it.