Hiatella

Hiatella is a genus of small saltwater clams, marine bivalve molluscs in the family Hiatellidae. These clams are known for their irregular shell shapes, often distorted by the crevices and spaces they inhabit.

Description

Hiatella shells are typically small to medium-sized, ranging from a few millimeters to a few centimeters in length. They are generally oblong or trapezoidal in shape, but highly variable. The shells are often thin and brittle, with a chalky or rough exterior. The surface may be sculptured with concentric growth lines and radial ribs, though these features can be subtle or absent. The periostracum (outer protein layer) is typically thin and may be brownish or grayish.

A key characteristic of Hiatella is its ability to bore into soft rock or other substrates, or to occupy pre-existing crevices and holes. This behavior often results in the shell taking on an irregular shape molded to the surrounding environment.

The interior of the shell is pearly white, and the hinge teeth are reduced or absent.

Habitat and Distribution

Hiatella species are found worldwide in intertidal and subtidal zones. They inhabit a wide range of marine environments, including rocky shores, mudflats, and algal beds. Their distribution is often linked to the availability of suitable substrates for boring or sheltering.

Ecology

Hiatella clams are filter feeders, using their gills to extract suspended organic matter and plankton from the water. They are often found attached to rocks, seaweed, or other hard surfaces by byssal threads (strong protein fibers secreted by the clam). They play a role in the marine ecosystem as both prey for larger invertebrates and fish, and as habitat providers for other small organisms.

Species

Several species are recognized within the genus Hiatella, including:

• Hiatella arctica (Linnaeus, 1767) – The most well-known and widely distributed species.
• Other less common or regionally restricted species.

Taxonomy

The genus Hiatella belongs to the family Hiatellidae, which is part of the order Myida. The taxonomic classification of Hiatella and related species has been revised over time, and some species may have been previously classified in different genera.