Homosclerophorida


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. Therefore, it has been recognized as the fourth class of sponges.
Homoscleromorpha are more closely related to eumetazoans than to the other sponge groups, therefore sponges are paraphyletic.
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. 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

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.