Homosclerophorida Explained

Homosclerophorida is an order of marine sponges. It is the only order in the monotypic class Homoscleromorpha. The order is composed of two families: Plakinidae and Oscarellidae.

Taxonomy

Homoscleromorpha is phylogenetically well separated from Demospongiae.^[1] Therefore, it has been recognized as the fourth class of sponges.^{[2] [3]}

It has been suggested that Homoscleromorpha are more closely related to eumetazoans than to the other sponge groups, rendering sponges paraphyletic.^[4] This view has not been supported by later work using larger datasets and new techniques for phylogenetic inference, which tend to support sponges as monophyletic, with Homoscleromorpha grouping together with Calcarea.^{[5] [6]}

On the basis of molecular and morphological evidence, the two families Plakinidae and Oscarellidae have been reinstated.

There are 117 species in this group divided into 9 genera.

The spiculate genera in this group are Aspiculophora, Corticium, Placinolopha, Plakina, Plakinasterella, Plakortis and Tetralophophora.

The aspiculate species are the genera Oscarella and Pseudocorticium.

Description

These sponges are massive or encrusting in form and have a very simple structure with very little variation in spicule form (all spicules tend to be very small). Reproduction is viviparous and the larva is an oval form known as an amphiblastula. This form is usual in calcareous sponges but is less common in other sponges.

Habitat

Homoscleromorpha are exclusively marine sponges that tend to encrust on other surfaces at shallow depths. These sponges typically inhabit shady locations, under overhangs and inside caves. In the Mediterranean Sea, 82% of the species in this taxon can be found in caves, and 41% of them are found nowhere else.^[7]

External links

• What are sponges? Queensland Museum
• Sponge guide

Notes and References

1. 10.1017/S0025315407058237. On the phylogenetic relationships of hadromerid and poecilosclerid sponges. Journal of the Marine Biological Association of the UK. 87. 6. December 2007. Kober . K. M. . Nichols . S. A. . 1585–1598. 84416168.
2. Gazave . Eve . Lapébie . Pascal . Renard . Emmanuelle . Vacelet . Jean . Rocher . Caroline . Ereskovsky . Alexander V. . Lavrov . Dennis V. . Borchiellini . Carole . Molecular phylogeny restores the supra-generic subdivision of homoscleromorph sponges (porifera, homoscleromorpha) . . 14 December 2010 . 5 . 12 . e14290 . 10.1371/journal.pone.0014290 . 21179486 . 3001884. free .
3. Gazave . Eve . Lapébie . Pascal . Ereskovsky . Alexander V. . Vacelet . Jean . Renard . Emmanuelle . Cárdenas . Paco . Borchiellini . Carole . May 2012 . No longer Demospongiae: Homoscleromorpha formal nomination as a fourth class of Porifera . . 687 . 1 . 3–10 . 10.1007/s10750-011-0842-x . 14468684 .
4. Sperling, Pisani and Peterson 2007, cited in: The Cambrian Explosion p. 80, Erwin and Valentine 2013
5. Nosenko, T., Schreiber, F., Adamska, M., Adamski, M., Eitel, M., Hammel, J., Maldonado, M., Müller, W. E. G., Nickel, M., Schierwater, B., Vacelet, J., Wiens, M., & Wörheide, G. (2013). Deep metazoan phylogeny: When different genes tell different stories. Molecular Phylogenetics and Evolution, 67(1), 223–233. https://doi.org/10.1016/j.ympev.2013.01.010
6. Laumer, C. E., Fernández, R., Lemer, S., Combosch, D., Kocot, K. M., Riesgo, A., Andrade, S. C. S., Sterrer, W., Sørensen, M. V., & Giribet, G. (2019). Revisiting metazoan phylogeny with genomic sampling of all phyla. Proceedings of the Royal Society B: Biological Sciences, 286(1906), 20190831. https://doi.org/10.1098/rspb.2019.0831
7. Ereskovsky, Alexander V. . Ivanisevic, Julijana . Pérez, Thierry . 2009 . Overview of the Homoscleromorpha sponges diversity in the Mediterranean . Conference: Proceedings of the 1st Mediterranean Symposium on the Conservation of the Coralligenous and Other Calcareous Bio-concretions .