Marine invertebrates: Sponge diversity

digital painting 2024

compare with some corals or colonial filterers

Porifera represent the most primitive stage of multicellular animals. They  have a low degree of cell diversification, show a sessile, filtering lifestyle, but persist to show impressive diversity and disparity from the uppermost Precambrian till today. True sponges (Demospongiae, common sponges) comprise the here shown round forms, with Siphonia (yellow) from the Cretaceous, as well as Astylospongia (orange) from the Cambrian and Ordovician. Glass sponges (Hexactinellida, containing siliceous spicules) count Coeloptychium (mushroom-shaped) and Ventriculites (blut) from the Cretaceous.  

On the lower left, there is a stromatopore, likely also some kind of sponge, but not certain. Stromatopores were important from the Ordovician to the Devonian, even forming reefs.