Why these sea snails defy the typical gastropod diet by acting like bivalves

Nature · Published 3 October 2026 Swipe more like this →

In short: Most sea snails are active hunters or scavengers, but the Turritellidae family—known as tower snails—have taken a different path. These marine gastropods have evolved to become filter feeders, a strategy rarely seen in their class but highly effective for life buried within the sand and mud of the ocean floor.

The Turritellidae family, often called tower shells, are easily identified by their high-spired, elongated shells. While they share a similar silhouette with auger shells, a closer look reveals distinct anatomical differences. Turritellid shells feature more convex whorls and circular apertures, complemented by a curved columella and a thin, multi-horned operculum. These physical traits support their unique lifestyle as sedentary filter feeders, a feeding method typically reserved for bivalves rather than gastropods.

These snails spend much of their lives partially submerged in soft substrates like mud or sand. Despite their relatively small feet, they are well-adapted to this burrowing existence. Their presence in the fossil record is significant, providing researchers with clear markers for ancient environmental conditions. For instance, the Erminger Turritellenplatte near Ulm, Germany, is a famous site where dense accumulations of Turritella turris shells are found within sandstone deposits. This site offers a window into the near-coastal, shallow marine environments of the past.

Geological and paleontological analysis of these deposits helps scientists date specific strata with remarkable precision. By examining the strontium-isotope composition of shark teeth found alongside these gastropod shells, researchers have dated the Erminger Turritellenplatte to approximately 18.5 million years ago, placing it within the Burdigalian age of the Lower Miocene epoch. Such findings illustrate how these humble snails serve as vital biological indicators, helping geologists correlate sedimentary deposits across vast temporal and spatial scales. Whether living in modern oceans or preserved in ancient stone, the Turritellidae remain a fascinating example of evolutionary adaptation within the marine world.

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