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Published on: May 14, 2019
Mechanisms of Shell Biomineralization in Recent Rhynchonelliform Brachiopods: Structure, Development, and Molecular
Anna V Ratnovskaya1,2, Aleksandra A Selischeva1, Tatyana V Kuzmina1
1Department of Invertebrate Zoology, Biological Faculty, Lomonosov Moscow State University, Moscow, Russia.
Journal of Morphology
|August 5, 2026
Summary
Rhynchonelliform brachiopods secrete shells via a conserved molecular mechanism and a cellular "conveyor belt" model. This precise cellular control facilitated complex lophophore support, driving their evolutionary success and diversity.
Area of Science:
- Paleontology
- Biomineralization
- Evolutionary Biology
Background:
- Brachiopods, originating in the Cambrian, feature the diverse Rhynchonelliformea subphylum.
- Rhynchonelliforms possess calcitic bivalve shells secreted by the mantle.
- Biomineralization processes in rhynchonelliform brachiopods are poorly understood.
Purpose of the Study:
- To review shell properties and mantle biology in rhynchonelliforms.
- To propose a comprehensive hypothesis for rhynchonelliform biomineralization.
- To present an ontogenetic model for shell secretion.
Main Methods:
- Review of published data on shell morphology, microstructure, and chemistry.
- Analysis of mantle ultrastructure, ontogeny, and molecular mechanisms.
- Synthesis of information to form a biomineralization hypothesis and ontogenetic model.
Main Results:
- Shell secretion involves a conserved molecular mechanism shared with other calcifying animals.
- An ontogenetic model suggests a cellular "conveyor belt" mechanism for shell secretion.
- High cellular control over shell growth is indicated by the narrow space and cell-mantle association.
Conclusions:
- Precise cellular control over shell growth likely enabled complex lophophore skeletal support.
- This trait played a key role in the evolutionary success and dominance of rhynchonelliform brachiopods.
- Rhynchonelliforms exhibit remarkable diversity and ecological dominance within the phylum due to these adaptations.
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