Stomatella Snail

Stomatella varia

Also known as Stomatella auricula, Fingernail Snail, Shell-less Snail, Slug Snail

SaltwaterSnail

Stomatella Snail (Stomatella varia) — Manuel CABALLER · CC BY 4.0

Care at a glance

Temperature: 75–81°F (24–27°C)
pH: 8.1–8.4
Adult size: 0.8 in (2 cm)
Minimum tank: 11 gal (40 L)
Temperament: Peaceful
Social behavior: Solitary
Swim level: Bottom
Difficulty: Beginner
Breeding: Easy
Rarity: Common
Reef safe: Reef safe
Origin: Indo-Pacific reefs and rubble, from shallow water to about 50 m
Family: Trochidae

Overview

An efficient, fast-moving grazer of film algae, diatoms and leftover food that works rock and glass mainly after dark, and it is often called one of the best invisible cleanup-crew animals because it needs no attention at all once it is established. It is a simultaneous hermaphrodite that cannot self-fertilize, so any two individuals in the same tank can pair up, and in a stable reef system a couple of stomatellas can multiply into a self-sustaining colony within months. It leaves corals and other invertebrates alone, though quick predators like six-line wrasses and peppermint shrimp will pick them off given the chance.

In the wild

Stomatella varia lives across Indo-Pacific reefs and rubble zones, from shallow water down to around 50 m, tucked into crevices and under rock during the day. It arrives in most tanks as a hitchhiker on live rock rather than a deliberate purchase, and once established it needs nothing more than ordinary reef rock and glass to graze; there is no special lighting, flow or feeding setup to plan around.

Good to know

Stomatella is a genus of small, fast-moving snails now placed in the family Trochidae, subfamily Stomatellinae, a group long treated as its own family, Stomatellidae. The hobby trade name Stomatella varia covers the common aquarium species, though some taxonomic authorities group it with the closely related, earlier-described Stomatella auricula. Unlike most snails in a cleanup crew it has a small, flattened, ear-shaped shell it cannot fully retract into and no operculum to seal the opening, staying under about 2 cm long.

Did you know

Unlike most snails, it has no operculum to seal itself inside its shell, so its backup defense is to drop the rear part of its own foot when grabbed, leaving it wriggling to distract a predator while the snail crawls away and slowly regrows what it lost.