Patellogastropods

Patellogastropods, commonly known as true limpets, are an order of marine gastropod mollusks within the class Gastropoda. They are among the more morphologically conservative groups of snails, characterized by a simple, cap-shaped shell and a large, muscular foot that enables strong adhesion to hard substrates in the intertidal and shallow subtidal zones.

The shell is typically a single, low-conical structure with the apex often positioned near the anterior edge. Most patellogastropods lack an operculum. The body extends beneath the shell, with the foot adapted for gripping rock surfaces against wave action. They occur worldwide, especially on rocky shores in temperate and tropical ecosystems.

Ecologically, patellogastropods are primarily herbivores that graze on biofilms, diatoms, and microalgae scraped from rocks with a toothed radula. They play a key role in controlling epilithic growth and contribute to the structure of intertidal communities. Reproduction is typically sexual, with external fertilization and free-swimming larval stages (trochophore and veliger) before settlement as juveniles.

In terms of classification, Patellogastropoda is considered one of the earliest-diverging lineages within Gastropoda. The group comprises several families, commonly referred to as true limpets, and has a substantial fossil record dating back to the Paleozoic era. Their relatively simple body plan and ecological role have made them a focus of studies on gastropod evolution and intertidal ecology.