Hexasterophora

Hexasterophora are a subclass of sponges, in the class Hexactinellida.[4] The Hexasterophora first appeared in the Ordovician and is separated into five recent orders, including the Lyssacinosa, the Hexactinosa, and the Lychniscosa, all of which have living representatives in the seas today.

Hexasterophora
Temporal range:
Scientific classification
Kingdom: Animalia
Phylum: Porifera
Class: Hexactinellida
Subclass: Hexasterophora
Schulze, 1886
Orders
Synonyms
  • Aulocalycoida Tabachnick & Reiswig, 2000[2]
  • Hexactinosida Schrammen, 1912 [3]

Hexasterophorans have skeletons composed of overlapping six-rayed spicules.[4] The sponge is commonly firmly attached by its base to a hard substratum; less often rooted by the anchoring spicules and rarely inserted directly into the loose bottom sediments. The three groups are differentiated by the extent of fusion of adjacent spicules.

The Lyssacinosa, Hexactinosa, and Lychniscosa appear sequentially in the fossil record. The least fused group, the Lyssacinosa, appears in the Ordovician, while the intermediate group, the Hexactinosa is known from the Devonian. Finally, the Lychniscosa, with the most tightly interlocking spicules is first found in rocks of Triassic age.

References
  1. Botting, J. P.; Janussen, D.; Muir, L. A.; Dohrmann, M.; Ma, J.; Zhang, Y. (March 2022). "Extraordinarily early Venus' flower basket sponges (Hexactinellida, Euplectellidae) from the uppermost Ordovician Anji Biota, China". Palaeontology. 65 (2). doi:10.1111/PALA.12592. ISSN 0031-0239. Wikidata Q111529763.
  2. "WoRMS - World Register of Marine Species - Aulocalycoida". www.marinespecies.org. Retrieved 11 June 2021.
  3. "WoRMS - World Register of Marine Species - Hexactinosida". www.marinespecies.org. Retrieved 11 June 2021.
  4. Access Science


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