Homosclerophorida is an order of marine

sponge Sponges, the members of the phylum Porifera (; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate throug ...

s. It is the only order in the monotypic class Homoscleromorpha. The order is composed of two families:

Plakinidae Plakinidae is a family of marine sponges. It is composed of seven genera: Plakinidae and Oscarellidae are the two families that compose the fourth and smallest class of the porifera phylum, Homoscleromorpha. * '' Aspiculophora'' Ruiz, Muricy, L ...

and

Oscarellidae Oscarellidae is a family of marine sponges. Genera * '' Oscarella'' Vosmaer, 1884 ** '' Oscarella balibaloi'' Pérez, Ivanisevic, Dubois, Pedel, Thomas, Tokina & Ereskovsky, 2011 ** '' Oscarella bergenensis'' Gazave, Lavrov, Cabrol, Renard, Roch ...

Taxonomy

Homoscleromorpha is phylogenetically well separated from

Demospongiae Demosponges (Demospongiae) are the most diverse class in the phylum Porifera. They include 76.2% of all species of sponges with nearly 8,800 species worldwide (World Porifera Database). They are sponges with a soft body that covers a hard, ...

. Therefore, it has been recognized as the fourth class of sponges. It has been suggested that Homoscleromorpha are more closely related to eumetazoans than to the other sponge groups, rendering sponges paraphyletic.Sperling, Pisani and Peterson 2007, cited in: The Cambrian Explosion p. 80, Erwin and Valentine 2013 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. On the basis of molecular and morphological evidence, the two families

and

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 ''Plakortis'' is a genus of marine sponges in the order Homosclerophorida, first described by Franz Eilhard Schulze in 1880. Description ''Plakortis'' sponges are characterised by having: #inorganic (spicular) skeletal complement #Skeleton comp ...

'' 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 Spicules are any of various small needle-like anatomical structures occurring in organisms Spicule may also refer to: *Spicule (sponge), small skeletal elements of sea sponges *Spicule (nematode), reproductive structures found in male nematodes ( ...

form (all spicules tend to be very small). Reproduction is

viviparous Among animals, viviparity is development of the embryo inside the body of the parent. This is opposed to oviparity which is a reproductive mode in which females lay developing eggs that complete their development and hatch externally from the ...

and the

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. ...

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.

References

External links

What are sponges? Queensland Museum

Sponge guide
Taxa named by Arthur Dendy {{demosponge-stub