Violet Risso – Rissoa violacea

, Violet Risso - Rissoa violacea, Rissoa violacea
Depth: 3 - 15 m
Water Type: Marine
Toxicity: Toxic hazard unknown
Red List Status: Not evaluated (NE)
Temperature: °F - 62.6 °F (°C - 17°C)

Rissoa violacea, commonly known as the Violet Risso, is a small, marine gastropod mollusk belonging to the family Rissoidae. This species is characterized by its distinctive purple-violet coloration and plays a crucial role in the delicate balance of its marine environment.

Description & Characteristics

The Violet Risso is a diminutive species, with adults typically reaching a maximum size of about 5 millimeters. The shell of Rissoa violacea is characterized by its conical shape and smooth, glossy surface. Its most striking feature is its vibrant purple-violet color, which can range from a deep, rich purple to a lighter, more lavender hue. This unique coloration is thought to provide camouflage, helping the snail blend into its surroundings and avoid predation. The aperture, or opening, of the shell is rounded and slightly angled, with a distinct lip that marks the edge.

Habitat and Occurrence

The Violet Risso is a common inhabitant of rocky shores and intertidal zones. It can be found in both the infralittoral and circalittoral zones, with a depth range typically extending from the low tide mark to depths of around 50 meters. Rissoa violacea prefers areas with a good supply of algae, as this provides them with their primary food source. This makes them particularly abundant in areas with rocky reefs, seawalls, and other structures that provide suitable habitat for algae to grow.

Taxonomy

Rissoa violacea is classified within the Class Gastropoda, Order Littorinimorpha, and Family Rissoidae. Gastropods are a diverse group of mollusks that include snails, slugs, and sea slugs, all of which possess a single, coiled shell. The Littorinimorpha are a large order within the Gastropoda, characterized by their typically well-developed operculum, a structure that acts as a door to close the shell opening. The Rissoidae are a family of small, often brightly colored gastropods, many of which are found in intertidal and shallow marine habitats.

Feeding

Rissoa violacea is an herbivorous grazer, primarily feeding on algae and epiphytes, which are small plants that grow on other organisms. They use their radula, a ribbon-like structure in their mouth covered in rows of teeth, to scrape algae from surfaces. Additionally, they are known to consume detritus, which consists of decaying organic matter. This varied diet contributes to their success in diverse habitats.

Associated Species

Image References

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