Roman Snail (Helix pomatia)

Roman Snail (Helix pomatia) (Linnaeus, 1758) is a land snail species belonging to the phylum Mollusca and the class Gastropoda. It is described as one of the largest land snails in Europe. Historically used as a food source, the species continues to be consumed by humans today.^【1】

Taxonomy and Genetics

Helix pomatia is the type species of the genus Helix. Phylogenetic analyses and molecular studies have provided new data on its taxonomic classification. Recent research has split the species into two distinct entities: Helix pomatia and Helix thessalica. Mitochondrial genome analyses indicate that Helix pomatia is the sister group to a clade including Cepaea nemoralis, Theba pisana, and Cornu aspersum.^【2】

The mitochondrial genome of the species has a typical metazoan structure, containing 13 protein-coding genes, two ribosomal RNAs, and 21 transfer RNAs. Sequence analysis reveals that the Cytochrome Oxidase subunit III and tRNA-Thr genes are rearranged compared to other members of the superfamily Helicoidea.^【3】

Roman Snail (Helix pomatia) - Pixabay

Morphological Characteristics

The shell of Helix pomatia is spherical and known for its robustness. Shell diameter typically ranges from 30 to 50 mm in height and 32 to 50 mm in width. The shell color is generally yellowish-brown or brown and may lighten under exposure to sunlight. The shell surface displays irregular, pale spiral markings.^【4】

Adult individuals usually have 4.5 to 5 whorls, while juveniles exhibit fewer. The surface of the head and foot is described as granular and irregular. During hibernation, snails secrete a calcareous, hard operculum to seal the shell aperture and protect themselves from adverse environmental conditions.^【5】

Distribution and Habitat

The species is native to Europe but has been introduced to Asia and the Americas by human activity. In natural habitats, it is commonly observed on shrubs, agricultural fields, around buildings, and on tree trunks, particularly during wet seasons. It feeds and reproduces on soil surfaces or within vegetation cover.^【6】

Nutritional Value and Consumption

The Roman snail is widely consumed in countries such as France, Belgium, Germany, and Italy. Nutritional analyses of the meat have revealed high protein content (13.4–16.33%) and low fat content (1.08–1.40%). The meat is also rich in essential fatty acids such as linolenic and linoleic acid. Mineral analysis shows that the meat contains high levels of copper (29.3 mg/100g), iron (14.0 mg/100g), and zinc compared to other meat types.^【7】

In Northern Cypriot cuisine, these snails are known as "garavolli" and are consumed boiled, grilled (as kebab), or pickled. When prepared as a stew, they are cooked with their shells intact.^【8】

Ecotoxicology and Bioaccumulation

Black snails is used as a bioindicator species for monitoring environmental pollution, particularly heavy metals, due to its soil-dependent lifestyle and limited mobility. A study conducted in the Kosovska Mitrovica region of Serbia analyzed heavy metal accumulation in Helix pomatia specimens.^【9】

Heavy Metal Accumulation and Organ Distribution

Bioaccumulation of metals in snail tissues varies according to environmental concentrations and the metabolic functions of the organs.

Hepatopancreas: The hepatopancreas, being the most metabolically active organ involved in digestion and detoxification, exhibits the highest concentration of accumulated metals. Elevated levels of copper, iron, manganese, lead, and zinc have been detected in this organ.^【10】

Kidney: Significant metal accumulation has also been observed in the kidneys, which play a role in excretion and detoxification.^【11】

Shell: The shell, composed of calcium carbonate, can act as a storage site for certain metals and serve as a long-term indicator of pollution. Notably, arsenic accumulation is significantly higher in the shell than in other tissues.^【12】

Hemolymph: The hemolymph, the circulatory fluid of the snail, contains high levels of copper due to its role as a respiratory pigment. However, levels of toxic metals such as lead and cadmium are reported to be low.^【13】

Age Factor

A correlation has been observed between snail age and heavy metal accumulation. Comparative analyses indicate that older snails have significantly higher concentrations of copper, iron, manganese, lead, and zinc in their hepatopancreas compared to middle-aged individuals. This may be attributed to longer exposure to pollution or age-related changes in metabolic processes.^【14】

Roman Snail (Helix pomatia) - Pixabay

Parasitology and Public Health

Land snails can serve as intermediate hosts for various parasites posing health risks to humans, including nematodes and trematodes. It is known that species such as Angiostrongylus cantonensis, as well as Fasciola hepatica and Fasciola gigantica, can infect snails.^【15】

In a field study conducted in 2019 in the Büyükkonuk region of Northern Cyprus, 250 wild-collected Helix pomatia specimens were examined, and no parasites were detected in any of the samples. Nevertheless, literature warns that consumption of raw or undercooked snails can lead to human infections, particularly when cooking methods such as shell-on preparation fail to reach internal temperatures sufficient to inactivate parasites.^【16】