''Oscarella tuberculata'' is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

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 ...

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 fr ...

. It is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to the Mediterranean Sea, where it forms encrusting colonies on rocks and other hard surfaces.

Description

''Oscarella tuberculata'' is a thickly encrusting sponge forming small patches up to in diameter. The tissue contains no

spongin Spongin, a modified type of collagen protein, forms the fibrous skeleton of most organisms among the phylum Porifera, the sponges. It is secreted by sponge cells known as spongocytes. Spongin gives a sponge its flexibility. True spongin is found ...

spicules 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 ( ...

but is firm to the touch, with a cartilage-like consistency. The surface is granular or wrinkled, with Irregular lobes and bulges, and small tubular structures emerging, some bearing osculae. This sponge is fairly uniform in colour, usually being yellowish-green, sometimes with a bluish tinge; occasionally, different parts of the colony differ in colour.

Distribution

''Oscarella tuberculata'' occurs in the Mediterranean Sea at depths of between about , on rocky substrates. It often grows in caves and under overhangs.

Biology

''Oscarella tuberculata'' is a

filter feeder Filter feeders are aquatic animals that acquire nutrients by feeding on organic matters, food particles or smaller organisms (bacteria, microalgae and zooplanktons) suspended in water, typically by having the water pass over or through a s ...

. Water is drawn into the interior of the sponge through minute pores called ostia, the organic particles and bacteria on which the sponge feeds are filtered out, and the water is pumped out through the osculae. Historically it has been thought that sponges in class

Homoscleromorpha 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 fr ...

did not reproduce asexually, but it has now been discovered that both ''Oscarella tuberculata'' and ''

Oscarella lobularis ''Oscarella lobularis'' is a species of sponge in the order Homosclerophorida. It is native to the northeastern Atlantic Ocean and the Mediterranean Sea, where it forms encrusting colonies on rocks and other hard surfaces. Description ''Oscarell ...

'' can reproduce by

budding Budding or blastogenesis is a type of asexual reproduction in which a new organism develops from an outgrowth or bud due to cell division at one particular site. For example, the small bulb-like projection coming out from the yeast cell is kno ...

. First an irregular protuberance forms near the base of the sponge, then it elongates to form a hollow nipple-like shape, in which the cavity is derived from the parent's exhalant channel. Finally, the swollen bubble-like structure breaks away from the parent sponge. The "bubble" is buoyant in the

water column The (oceanic) water column is a concept used in oceanography to describe the physical (temperature, salinity, light penetration) and chemical ( pH, dissolved oxygen, nutrient salts) characteristics of seawater at different depths for a defined ...

for a few days before settling on the seabed and attaching to the

substrate Substrate may refer to: Physical layers *Substrate (biology), the natural environment in which an organism lives, or the surface or medium on which an organism grows or is attached ** Substrate (aquatic environment), the earthy material that exi ...

, assisted by small conical outgrowths. It develops into a juvenile sponge with an oscula in four to ten days. This budding process in Homoscleromorpha is unique among sponges, as the tissue involved is all derived from

epithelial cells Epithelium or epithelial tissue is a thin, continuous, protective layer of cells with little extracellular matrix. An example is the epidermis, the outermost layer of the skin. Epithelial ( mesothelial) tissues line the outer surfaces of man ...

and does not involve the migration of

mesohyl The mesohyl, formerly known as mesenchyme or as mesoglea, is the gelatinous matrix within a sponge. It fills the space between the external pinacoderm and the internal choanoderm. The mesohyl resembles a type of connective tissue and contains ...

cells (the gelatinous matrix in the interior of the sponge) into the bud as it forms.

Ecology

This is a vigorous species of sponge; it overgrows the surface of larger sponges,

sea fans Alcyonacea is the old scientific order name for the informal group known as "soft corals". It is now an unaccepted name for class Octocorallia. It became deprecated . The following text should be considered a historical, outdated way of treating ...

and

bryozoa Bryozoa (also known as the Polyzoa, Ectoprocta or commonly as moss animals) are a phylum of simple, aquatic animal, aquatic invertebrate animals, nearly all living in sedentary Colony (biology), colonies. Typically about long, they have a spe ...

ns.

Sea slug Sea slug is a common name for some Marine biology, marine invertebrates with varying levels of resemblance to terrestrial Slug, slugs. Most creatures known as sea slugs are gastropods, i.e. they are Sea snail, sea snails (marine gastropod moll ...

s such as '' Berthella plumula'' feed on this sponge.

References

{{Taxonbar, from= Q4117251 Homoscleromorpha Fauna of the Mediterranean Sea Taxa named by Eduard Oscar Schmidt Animals described in 1868