Tightening it Up: Diversity of the Chitin Anchorage of Radular-Teeth in Paludomid Freshwater-Gastropods

Abstract

The radula is the anatomical structure used for feeding in most Mollusca species and is one important autapomorphy. Previous studies were focused on the radular teeth and their functional morphology, but their anchorage in the radular membrane and its function have never been examined. Here, we analyse the micro-structure of connecting chitinous fibres and its implication on the radular function in 13 closely related paludomid gastropod species from the so called “ancient lake” Tanganyika. This species flock shows a stunning interspecific diversity in their radular tooth morphology and tooth embedding in the membrane as well. The species studied here feed on organics from different substrates, both soft and solid, and are substrate-specific. Here, the morphological composition of the membrane is described in detail for the first time, it consists of parallel fibres that extend also within the teeth. We also show that morphologies of the anchorage correlated with the specific preferred feeding substrate can hence be identified as functional adaptation.