''Oscarella carmela'', commonly known as the slime sponge, is a species of sponge in the order

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 ...

that was first described in 2004 by G. Muricy and J.S. Pearse. It is believed to be native to intertidal waters in the north east temperate Pacific Ocean and was first found in seawater aquaria in that region. It is used as a

model organism A model organism (often shortened to model) is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the model organism will provide insight into the workin ...

in evolutionary biology.

Description

''Oscarella carmela'' is either encrusting or massive and forms a slimy covering or a thicker layer of spongy matter with an uneven, lumpy, lobed surface. It grows in patches on hard substrates up to in diameter and overgrows other organisms. The colour is variable and ranges from orange-brown to tan or beige. This sponge does not contain spicules or spongin to reinforce its body wall and has a simple structure with only two types of cell with inclusions.

Distribution and habitat

''Oscarella carmela'' is believed to be a native of northern and central Californian marine waters. It was first observed in Monterey Bay Aquarium and several research seawater aquaria in western California. It was later searched for, and eventually found, in the sea on the underside of boulders in rock pools in the high

intertidal zone The intertidal zone, also known as the foreshore, is the area above water level at low tide and underwater at high tide (in other words, the area within the tidal range). This area can include several types of habitats with various species o ...

Carmel Bay Carmel Bay is a bay of the Pacific Ocean, along the central coast of California in Monterey County. The bay is long and wide with its mouth about across, between Point Carmel to the south and Point Cypress to the north; Monterey Bay is about f ...

. Although it was not described until 2004, it is not believed to be an

invasive species An invasive species otherwise known as an alien is an introduced organism that becomes overpopulated and harms its new environment. Although most introduced species are neutral or beneficial with respect to other species, invasive species ad ...

in the United States but is more likely to be indigenous and have been overlooked previously because it is uncommon and very similar to more common ''

Halisarca Halisarcidae is a family of sea sponges within the order Chondrillida. Members of the family are characterised by having long tubular, branched choanocyte chambers; they have no spicules which makes it difficult to determine the group's affinitie ...

'' species. It is in fact the only member of its genus '' Oscarella '' to be found in the eastern Pacific. It is hypothesized that in the wild it may be limited in its distribution by predation, whereas in the protected environment of an aquarium it grows profusely.

Biology

Like other sponges, ''Oscarella carmela'' is a

filter feeder Filter feeders are a sub-group of suspension feeding animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized filtering structure. Some animals that use this method of feedin ...

. It creates a current of water through its interior from which it extracts bacteria and planktonic food particles. Reproduction is viviparous and the planktonic larvae are the oval type known as amphiblastulae. This type of larval form is quite common in calcareous sponges but is unusual in other sponge groups. The genome of ''Oscarella carmela'' has been sequenced and it is used as a model in evolutionary developmental biology. Analysis of the genome suggests that the last common ancestor of sponges and eumetazoan animals (a

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

that contains all the higher animals except the sponges and placozoans) was more complex both genetically and morphologically than had previously been thought. The data suggest that homoscleromorph sponges have retained certain features that have been lost in other demosponges.

References

{{Taxonbar, from=Q4116895 Animals described in 2004 Animal models Evolutionary biology Homoscleromorpha