''Cliona viridis'', commonly called the green boring sponge, 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), ...

demosponge 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 A species () is often de ...

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Clionaidae Clionaidae is a family of ectoparasitic demosponges which are found worldwide. This group of sponges are well known for boring holes in calcareous material such as mollusc shells and coral Corals are colonial marine invertebrates within the ...

. Its form varies according to the nature of the surface on which it grows. In limestone and other calcareous substrates it excavates channels and chambers while on other types of rock it encrusts the surface or forms massive structures. It is native to the eastern Atlantic, the Mediterranean Sea and the Indo-Pacific Ocean.

Description

''Cliona viridis'' is an excavating sponge and on calcareous substrates, the mass of the sponge is largely unseen beneath the surface with just the osculi (exhalent openings) and ostioles (inhalent pores) projecting. The osculi are a few millimetres wide and are yellowish-green or light brown with pale rims. The ostioles are grouped together on flat-topped, sieve-like protuberances which may be white, yellow or brownish-green. The colour is due to the

zooxanthellae Zooxanthellae (; zooxanthella) is a colloquial term for single-celled photosynthetic organisms that are able to live in symbiosis with diverse marine invertebrates including corals, jellyfish, demosponges, and nudibranchs. Most known zooxanthell ...

which are present in the tissues. The exterior appearance of this sponge in its later growth stages is a smooth mosaic-like surface composed of a firm, tough material. Beneath this surface are galleries excavated by the sponge which are up to in diameter. The whole sponge may be a globose structure some in diameter.

Distribution

''Cliona viridis'' is found in the East Atlantic, the

Azores The Azores ( , , ; , ), officially the Autonomous Region of the Azores (), is one of the two autonomous regions of Portugal (along with Madeira). It is an archipelago composed of nine volcanic islands in the Macaronesia region of the North Atl ...

, the

Cape Verde Islands Cape Verde or Cabo Verde, officially the Republic of Cabo Verde, is an island country and archipelagic state of West Africa in the central Atlantic Ocean, consisting of ten volcanic islands with a combined land area of about . These islands ...

, the

Mediterranean Sea The Mediterranean Sea ( ) is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean basin and almost completely enclosed by land: on the east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern Eur ...

and the

Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or approximately 20% of the water area of Earth#Surface, Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia (continent), ...

. It has also been reported from the Caribbean Sea but this may have been a misidentification. It is found in shallow water and at depths down to about , in well-lit areas and in semi-dark cave entrances. ''Cliona viridis'' is a common sponge and is the dominant species of sponge in the shallow

sublittoral zone The neritic zone (or sublittoral zone) is the relatively shallow part of the ocean above the drop-off of the continental shelf, approximately in depth. From the point of view of marine biology it forms a relatively stable and well-illuminated ...

in some parts of its range. It is less frequently found in deeper water and there it largely grows on

coralline algae Coralline algae are red algae in the order Corallinales. They are characterized by a thallus that is hard because of calcareous deposits contained within the cell walls. The colors of these algae are most typically pink, or some other shade of re ...

Biology

In the first stage of growth, ''Cliona viridis'' needs a calcified substrate on which to grow and into which it can bore. This can be

limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

or a

mollusc shell The mollusc (or mollusk) shell is typically a calcareous exoskeleton which encloses, supports and protects the soft parts of an animal in the phylum Mollusca, which includes snails, clams, tusk shells, and several other classes. Not all shelled ...

such as that of the edible oyster (''Ostrea edulis''). In its encrusting and massive stages it can grow over silicaceous rocks into which it is unable to bore. Although the tissues normally contain zooxanthellae, a

photosynthetic Photosynthesis ( ) is a Biological system, system of biological processes by which Photoautotrophism, photosynthetic organisms, such as most plants, algae, and cyanobacteria, convert light energy, typically from sunlight, into the chemical ener ...

symbiont Symbiosis (Ancient Greek : living with, companionship < : together; and ''bíōsis'': living) is any type of a close and long-term biological interaction, between two organisms of different species. The two organisms, termed symbionts, can fo ...

, the sponge is not reliant on this and can grow in total darkness. Like other sponges, ''Cliona viridis'' maintains a current of water through its structure. It draws water in through its ostioles and filters out food particles such as

bacteria Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of Prokaryote, prokaryotic microorganisms. Typically a few micr ...

and other micro-organisms. During the passage of the water through the sponge, oxygen diffuses into the tissues and waste products diffuse out. The water is then expelled through the osculi. ''Cliona viridis'' is

oviparous Oviparous animals are animals that reproduce by depositing fertilized zygotes outside the body (i.e., by laying or spawning) in metabolically independent incubation organs known as eggs, which nurture the embryo into moving offsprings kno ...

, that is to say the

eggs An egg is an organic vessel in which an embryo begins to develop. Egg, EGG or eggs may also refer to: Biology * Egg cell, the female reproductive cell (gamete) in oogamous organisms Food * Eggs as food Places * Egg, Austria * Egg, Switzerland ...

are fertilised internally, sperm being drawn into the interior of the sponge with the incoming water flow. The eggs are then ejected into 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 ...

via the outgoing water stream. There is some degree of synchronisation of the reproductive process as a

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 ...

l bloom was observed to take place in June during a study undertaken in the Mediterranean. The larvae are

plankton Plankton are the diverse collection of organisms that drift in Hydrosphere, water (or atmosphere, air) but are unable to actively propel themselves against ocean current, currents (or wind). The individual organisms constituting plankton are ca ...

ic and have limited dispersal ability. When they settle on the seabed they develop into juvenile sponges in about two weeks. Zooxanthellae are already present at

metamorphosis Metamorphosis is a biological process by which an animal physically develops including birth transformation or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and different ...

, having probably been transmitted during maturation of the

oocyte An oocyte (, oöcyte, or ovocyte) is a female gametocyte or germ cell involved in reproduction. In other words, it is an immature ovum, or egg cell. An oocyte is produced in a female fetus in the ovary during female gametogenesis. The female ger ...

References

{{Taxonbar, from=Q2979374 Sponges described in 1862 Fauna of the Mediterranean Sea Sponges of the Atlantic Ocean Sponges of the Indian Ocean Hadromerida