Systematics and Phylogeny of Porifera

Sponges (phylum Porifera) represent the earliest-diverging lineage of multicellular animals, distinguished by their porous bodies, internal skeletal elements and remarkable morphological diversity. Traditional systematics, rooted in skeletal architecture and spicule morphology, has long recognised four major classes: Demospongiae, Calcarea, Hexactinellida and Homoscleromorpha. However, advances in molecular phylogenetics have repeatedly challenged this framework, revealing polyphyletic assemblages and uncovering cryptic clades. Integration of ribosomal and mitochondrial markers, ultraconserved genomic regions and fossil calibrations has refined divergence estimates, suggesting a Neoproterozoic origin of sponges and multiple independent acquisitions of siliceous skeletons. Modern classification now emphasises monophyletic groupings supported by combined morphological and molecular evidence, while addressing incongruences through targeted taxon sampling and genome‐scale analyses. These developments not only deepen understanding of early metazoan evolution but also inform ecological assessments, bioprospecting of sponge‐derived biomolecules and conservation strategies for reef ecosystems.

Research from Nature Portfolio

Recent studies have characterised silica-associated proteins in hexactinellid sponges, revealing independent evolutionary pathways for biomineralisation across major sponge lineages. Two novel proteins, hexaxilin and perisilin, are shown to pattern axial symmetry and peripheral thickening of skeletal elements, respectively, using distinct intracellular and extracellular mechanisms. These findings support a scenario in which ancestral Porifera lacked mineralised skeletons and later acquired siliceous frameworks convergently in different classes. Such evidence reconciles molecular-clock estimates with the fossil record and challenges uniform models of sponge skeletal evolution, underscoring the modular and dynamic nature of metazoan silicification.

Systematics and Phylogeny of Porifera publication trend

The graph below shows the total number of articles in systematics and phylogeny of porifera across all publications each year (not limited to Nature Index journals).

Technical terms

Porifera: Phylum of multicellular animals commonly known as sponges, characterised by porous bodies, canal systems and internal skeletal elements.

Systematics: Scientific discipline concerned with classifying organisms and elucidating their evolutionary relationships.

Phylogeny: Evolutionary history and branching relationships among species or clades.

Spicule: Microscopic skeletal element, composed of silica or calcium carbonate, providing structural support in sponges.

Ultraconserved elements (UCEs): Highly conserved genomic regions used as markers in multilocus phylogenetic analyses.

Monophyly: Condition in which a group comprises an ancestor and all its descendants, forming a single, complete clade.

References

1. Silica-associated proteins from hexactinellid sponges support an alternative evolutionary scenario for biomineralization in Porifera. Nature Communications (2024).
2. A novel target‐enriched multilocus assay for sponges (Porifera): Red Sea Haplosclerida (Demospongiae) as a test case. Molecular Ecology Resources (2023).
3. Proposal for a revised classification of the Demospongiae (Porifera). Frontiers in Zoology (2015).
4. Divergence times in demosponges (Porifera): first insights from new mitogenomes and the inclusion of fossils in a birth-death clock model. BMC Ecology and Evolution (2018).