Other non-marine invertebrates

Open Access
Publisher Website
Google Scholar
Abstract
Two classes of Mollusca have successfully emerged from the sea: the Bivalvia to fresh waters but the Gastropoda, in addition to invading the fresh water habitat, have also become fully air-breathing and live on the land. There is today a complete range from those taxa that are in every respect fully marine to those that are completely independent of the sea. The possible pathways from the sea to these environments are by surviving reduced or varying salinities, which it might be assumed occur in intertidal or estuarine conditions, or by surviving periodic and increasing exposure in air, again a condition of the intertidal environment. The prerequisite for emergence from the sea must have been the presence of food. In the initial emergence this could have been provided by detritus derived from the sea and deposited along a feature such as a storm beach. Such an environment is probably important for some Ellobiidae today. To spread onto the land and into the fresh water Mollusca, as other essentially grazing or suspension feeding animals, were presumably preceded by Bacteria or plants, or both. The initial modifications to metabolic and reproductive processes, outlined by Little (1983), may have taken place high in the littoral zone, supported by detritus and, as in the Ellobiidae, remaining dependent on the sea during larval life. The expansion and radiation of the Mollusca that has followed may have been related to the increase in habitats made available by the plants.

This publication has 1 reference indexed in Scilit: