Homosclerophorida is an order of marine
sponge
Sponges or sea sponges are primarily marine invertebrates of the animal phylum Porifera (; meaning 'pore bearer'), a basal clade and a sister taxon of the diploblasts. They are sessile filter feeders that are bound to the seabed, and a ...
s. 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
Demosponges or common sponges are sponges of the class Demospongiae (from + ), the most diverse group in the phylum Porifera which include greater than 90% of all extant sponges with nearly 8,800 species worldwide (according to the World P ...
. 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
Plakinidae and
Oscarellidae have been reinstated.
There are 136 species in this group divided into 10 genera.
The spiculate genera in this group are ''
Aspiculophora'', ''
Aspiculortis'', ''
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
Reproduction (or procreation or breeding) is the biological process by which new individual organisms – "offspring" – are produced from their "parent" or parents. There are two forms of reproduction: Asexual reproduction, asexual and Sexual ...
is
viviparous and the
larva
A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...
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 MuseumSponge guide
Taxa named by Arthur Dendy
Sponge orders
{{demosponge-stub