''Cliona viridis'', commonly called the green boring sponge, is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

demosponge 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 har ...

in the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Clionaidae Clionaidae is a family of demosponges which are found worldwide. This family is known for parasitically boring holes in calcareous material such as mollusc shells and corals, using both chemical and mechanical processes.Brusca, R.C. & Brusca, G. ...

. 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 is a colloquial term for single-celled dinoflagellates that are able to live in symbiosis with diverse marine invertebrates including demosponges, corals, jellyfish, and nudibranchs. Most known zooxanthellae are in the genus ''S ...

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

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, the

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, 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 north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the ...

and the

Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or ~19.8% of the water on Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia to the east. To the south it is bounded by t ...

. 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 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 ...

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 ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

or a

mollusc shell The mollusc (or molluskOften spelled mollusk shell in the USA; the spelling "mollusc" are preferred by ) shell is typically a calcareous exoskeleton which encloses, supports and protects the soft parts of an animal in the phylum Mollusca, wh ...

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

symbiont Symbiosis (from Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or parasi ...

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

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, that is to say the

eggs Humans and human ancestors have scavenged and eaten animal eggs for millions of years. Humans in Southeast Asia had domesticated chickens and harvested their eggs for food by 1,500 BCE. The most widely consumed eggs are those of fowl, especial ...

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 A water column is a conceptual column of water from the surface of a sea, river or lake to the bottom sediment.Munson, B.H., Axler, R., Hagley C., Host G., Merrick G., Richards C. (2004).Glossary. ''Water on the Web''. University of Minnesota-D ...

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

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. ...

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 found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a crucia ...

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, 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 femal ...

References

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