Microplastics, small plastic particles less than 5 mm in diameter, are widespread pollutants in marine ecosystems. This study investigates the ingestion of microplastics by zooplankton, a critical component of marine food webs. Using fluorescence and CARS microscopy, researchers found that 13 zooplankton species, including copepods, bivalve larvae, and decapod larvae, can ingest microplastics ranging from 1.7 to 30.6 µm in size. Microplastics were observed to be ingested via filter-feeding and later egested in faecal pellets. Some microplastics adhered to the external surfaces of zooplankton, particularly in dead specimens. The copepod Centropages typicus showed a significant reduction in algal ingestion when exposed to 7.3 µm microplastics, indicating a negative impact on zooplankton feeding. The study highlights the potential for microplastics to affect zooplankton function and health, with implications for marine ecosystems. The findings suggest that microplastics may accumulate in zooplankton, potentially leading to long-term ecological consequences. The research underscores the need for further investigation into the effects of microplastics on marine life.Microplastics, small plastic particles less than 5 mm in diameter, are widespread pollutants in marine ecosystems. This study investigates the ingestion of microplastics by zooplankton, a critical component of marine food webs. Using fluorescence and CARS microscopy, researchers found that 13 zooplankton species, including copepods, bivalve larvae, and decapod larvae, can ingest microplastics ranging from 1.7 to 30.6 µm in size. Microplastics were observed to be ingested via filter-feeding and later egested in faecal pellets. Some microplastics adhered to the external surfaces of zooplankton, particularly in dead specimens. The copepod Centropages typicus showed a significant reduction in algal ingestion when exposed to 7.3 µm microplastics, indicating a negative impact on zooplankton feeding. The study highlights the potential for microplastics to affect zooplankton function and health, with implications for marine ecosystems. The findings suggest that microplastics may accumulate in zooplankton, potentially leading to long-term ecological consequences. The research underscores the need for further investigation into the effects of microplastics on marine life.