Morphological characters explained

Soft tissues




Shell shape, size and ornamentation are key features in heteropod species identification.





There are two types of atlantid radula:

Type I: Teeth are never cast off, so the number of tooth rows increases continuously. All stages from juvenile to adult are present in mature specimens.

Type II: Teeth are cast off  the anterior end of the radula once a set number of tooth rows is reached (this number varies by species, see table below).


The overall shape of the radula is also useful for species identification, although there is sexual dimorphism of the radula in many atlantid species. For more information on radulae see the 



This research was carried out at Naturalis Biodiversity Center and the University of Plymouth with funding from the Leverhulme Trust and the NBC Martin-Fellowship. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 746186.

© 2017 Deborah Wall-Palmer