Hexasterophora

Hexasterophora is a grouping within the demosponges, a major class of the phylum Porifera. It is defined by the presence of hexaster microscleres in the sponge’s skeleton. The rank and composition of Hexasterophora have varied among classifications: some systems treat it as a suborder or clade within Demospongiae, while others place similar taxa in related groups that share hexasterous spicules.

Morphology and skeletal structure

Hexasterophorans typically possess a silica-based skeleton that includes hexaster microscleres, often arranged in a supporting reticulation together with other spicule types. The specific combination of spicules can vary among lineages, but the hexaster morphology is a defining feature used to distinguish them in many taxonomic schemes.

Distribution and habitat

Members of this grouping are marine and occupy a range of habitats, from shallow coastal environments to deeper seas. They are globally distributed and can contribute to sponge communities on reefs, rocky substrates, and soft bottoms.

Ecology and reproduction

Hexasterophorans are sessile filter feeders, drawing water through their canal systems to extract suspended particles. Many species are hermaphroditic, with sexual reproduction involving broadcast spawning and free-swimming larvae. Asexual reproduction, through budding or fragmentation, also occurs in some taxa.

Fossil record and taxonomy

Spicule morphology enables paleontologists to identify hexaster-bearing sponges in the fossil record, which extends back to ancient marine ecosystems. Due to ongoing revisions in sponge systematics, often driven by molecular data, the exact boundaries and rank of Hexasterophora have evolved, with contemporary classifications integrating both morphological and genetic information.