<p>In recent years, sea hares (family Aplysiidae) have attracted growing interest as potential bioindicators for environmental research in coastal regions, although they are not yet as widely utilized as other marine organisms commonly found in these habitats. Sea hares exhibit several characteristics that make them promising candidates for local environmental monitoring: They are easy to sample, relatively small in size, and reside in sedentary coastal environments that are especially susceptible to pollution. Their grazing behavior also increases their potential for bioaccumulating environmental contaminants. While methodological standardization and regulatory frameworks for using sea hares in both field and laboratory studies are less developed compared to more established molluscan bioindicators, numerous studies have documented their ability to accumulate organic and inorganic pollutants. In addition, their physiological and behavioral responses, such as alterations in feeding, locomotion, and neural activity, offer valuable insights into the neurotoxic effects of environmental stressors. This review outlines the current ecotoxicological and environmental applications of sea hares and underscores the importance of integrating molecular and biochemical approaches to further establish their utility as a promising molluscan model. In particular, we emphasize their potential for site-specific assessments of contaminant exposure and ecological impact in coastal ecosystems. Despite certain limitations in their use as laboratory toxicity models, we hope this review encourages broader adoption of sea hares as effective bioindicators in coastal environmental monitoring and research.</p>