Gastropoda, Cuvier, 1795

3.1.3.1. Gastropoda

Gastropods live on sediments, sandy bottoms, rocks, and the seabed and are exposed to direct and indirect MP pollution (Zaki et al., 2021). They can uptake MPs from the water column, sediment, and nutrients. MP contamination was observed especially in the outer shells, foot, pedal mucus, and feces of snails, indicating that they ingest and excrete MPs (Rodrigues et al., 2023). Gastropods are known for their diverse feeding habits, which include herbivory, detritivory, suspension feeding, scavenging, and carnivory (Srivastava and Singh, 2021). As detritivores, they feed on detritus and intake MPs from the sediment. They are also grazers on macroalgae and consume MPs in seagrasses while feeding ( Curren et al., 2024).

Gastropods move by crawling with the help of their pedal mucus and feet. In the Bohai Sea, crawling species such as Rapana venosa , Neverita didyma , Chlorostoma rustica , Buccinum koreana , Siphonalia subdilatata , Volutharpa perryi , Natica janthostomoides , and Natica maculosa were found to have higher MP contents than bivalve species that burrow in the sediment or attach to rocks (e.g., Solen gouldi and Mytilus galloprovincialis ) (Zhao et al., 2024). The researchers noted that the high MP ratio in crawling shells may be related to MP uptake from both sediment and water during crawling.

A study conducted in the Klang River estuary in Malaysia found that the carnivorous snails Chicoreus cingulata and Thais mutabilis contained more MPs than the herbivorous snails Nerita articulata and Nerita polita . This difference in MP concentration was attributed to the feeding habits of these snails; herbivorous snails consume algae containing MPs, while carnivorous snails consume both the MPs in the environment and in their prey (Zaki et al., 2021). This study highlighted that MPs can be transferred from one organism to another through trophic pathways, raising concerns about the potential risks posed to humans by aquatic foods that may contain MPs.

We examined the abundance of MPs in 23 gastropod species across 13 studies (Appendix Table 1 View Table 1 ). The presence of MPs in soft tissues has been studied most in the literature. The most commonly used digestion method was 10% KOH. For polymer analysis, the majority of studies utilized µFTIR and FTIR. The predominant shapes of MPs identified were fibers, followed by fragments. The most commonly detected polymers were PE and PET. The highest MP concentration was found in the mangrove snail Littoraria scabra in Jakarta Bay, Indonesia (mean: 75.5 MPs/individual) (Patria et al., 2020). The minimum MP concentration (mean: 0.29 ± 0.54 MPs/individual) was recorded in the limpet Patella caerulea in İskenderun Bay and Mersin Bay, Türkiye (Yücel and Kılıç, 2023).