Limpet (Cellana spp.) shape is correlated with basalt or eolianite coastlines: Insights into prehistoric marine shellfish foraging and mobility in the Hawaiian Islands

Abstract

Marine molluscs are highly diverse in size, anatomical structure, behaviour, and habitat and can provide information on human foraging, mobility, diet, and palaeoenvironments. Molluscs occupy a variety of substrates including rocky shores, coral reefs, mud flats, and sandy beaches and shell morphology reflects their habitat and mode of life (e.g., mobility, method of feeding, defence against predators). The north windward coast of west Moloka‘i, Hawaiian Islands, consists mostly of smooth basalt boulders, with sections of eolianite (limestone) shoreline. These contrasting littoral shores influence the composition of the rocky shore intertidal mollusc populations, but both support large numbers of the ubiquitous Hawaiian limpet (Cellana exarata, C. sandwicensis, C. talcosa). We investigated if limpet shell shape (i.e., form and dimensions) varied between shoreline types by multi-year sampling of modern mollusc populations on basalt and eolianite coastlines. Using multiple discriminant analysis, modern shell shape was compared to archaeological limpet assemblages from three late prehistoric habitation sites adjacent to basalt and eolianite shorelines. Our results demonstrate that archaeological shell shape correlates to modern limpet shell shape from nearby basalt or eolianite coastlines suggesting low forager mobility during late prehistory.