''Porites lobata'', known by the common name lobe coral, is a species of stony coral 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 ...

Poritidae Poritidae is a family of stony corals. Members of the family are colonial hermatypic (reef-building) corals. They are variable in size and form but most are massive, laminar or ramose as well as branching and encrusting. The corallites are compa ...

. It is found growing on

coral reef A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in groups. C ...

s in tropical parts of the Indian and Pacific Oceans.

Description

''Porites lobata'' is a

hermatypic Hermatypic corals are those corals in the order Scleractinia which build reefs by depositing hard calcareous material for their skeletons, forming the stony framework of the reef. Corals that do not contribute to coral reef development are referred ...

or reef-building coral. It varies greatly in size and shape depending on its environment. On wave-exposed reef slopes it is encrusting whereas in calm water areas it can grow into large helmet-shaped or hemispherical hummocks up to high and wide. Growth rates are very slow, sometimes being as little as per year, and this means that large corals are very old. The general colour is greenish, yellow or tan because of 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 ...

, single-celled microalgae, that live symbiotically within the tissues. These make organic nutrients available to the polyps through

photosynthesis Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored i ...

.Genus ''Porites'', Family Poritidae: ''Porites lobata''
WetWebMedia.com. Retrieved 2011-12-19. The corallites are very small and closely packed. They are joined directly to one another by fused but porous walls and have diagnostic skeletal characteristics that are only visible under the microscope. The

septa The Southeastern Pennsylvania Transportation Authority (SEPTA) is a regional public transportation authority that operates bus, rapid transit, commuter rail, light rail, and electric trolleybus services for nearly 4 million people in five c ...

are also fused. The polyps are 1 millimetre (0.04 in) in diameter and the

coenosarc In corals, the coenosarc is the living tissue overlying the stony skeletal material of the coral. It secretes the coenosteum, the layer of skeletal material lying between the corallites (the stony cups in which the polyps sit). The coensarc is comp ...

covering the skeleton is thin.

Distribution

''Porites lobata'' is a common species of coral and is found in the tropical parts of the Indian and Pacific Oceans. The range extends from East Africa, the

Red Sea The Red Sea ( ar, البحر الأحمر - بحر القلزم, translit=Modern: al-Baḥr al-ʾAḥmar, Medieval: Baḥr al-Qulzum; or ; Coptic: ⲫⲓⲟⲙ ⲛ̀ϩⲁϩ ''Phiom Enhah'' or ⲫⲓⲟⲙ ⲛ̀ϣⲁⲣⲓ ''Phiom ǹšari''; ...

and the Gulf of Aden, through Indonesia and Australian waters to the Pacific coasts of

Gulf of California The Gulf of California ( es, Golfo de California), also known as the Sea of Cortés (''Mar de Cortés'') or Sea of Cortez, or less commonly as the Vermilion Sea (''Mar Bermejo''), is a marginal sea of the Pacific Ocean that separates the Baja C ...

and Central America. It is the most common coral species in

Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only state ...

. It is often the dominant species on reef margins, in lagoons and on fringing reefs at depths down to . It occurs in a slightly deeper zone than cauliflower coral.Marine Life Profile: Lobe Coral
Waikïkï Aquarium. Retrieved 2011-12-19.

Biology

''Porites lobata'' is

gonochoristic In biology, gonochorism is a sexual system where there are only two sexes and each individual organism is either male or female. The term gonochorism is usually applied in animal species, the vast majority of which are gonochoric. Gonochorism c ...

which means that individual colonies are either male or female. Gametes are liberated 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 ...

and the developing

planula A planula is the free-swimming, flattened, ciliated, bilaterally symmetric larval form of various cnidarian species and also in some species of Ctenophores. Some groups of Nemerteans also produce larvae that are very similar to the planula, which ...

larvae drift with the currents as part of the

zooplankton Zooplankton are the animal component of the planktonic community ("zoo" comes from the Greek word for ''animal''). Plankton are aquatic organisms that are unable to swim effectively against currents, and consequently drift or are carried along by ...

. These later settle, undergo metamorphosis and develop into polyps which found new colonies. Mortality is very high and very few recruits are found in the Eastern Pacific. Fragments of coral that become detached from the colony may also develop into new colonies. Breakup may happen as a result of wave damage or it may be due to the skeletal structure of the coral being weakened by the boring activities of date mussels ('' Lithophaga'' spp.) or the feeding activities of fish such as the stone triggerfish (''Pseudobalistes naufragium'').

Ecology

''Porites lobata'' forms part of the coral reef

biome A biome () is a biogeographical unit consisting of a biological community that has formed in response to the physical environment in which they are found and a shared regional climate. Biomes may span more than one continent. Biome is a broader ...

. Several fish species live among the lobes of the coral, some sheltering there and others, like the puffer fish (''

Arothron meleagris ''Arothron meleagris'', commonly known as the guineafowl puffer or golden puffer, is a pufferfish from the Indo-Pacific, and Eastern Pacific. It is occasionally harvested for the aquarium trade. It reaches 50 cm in length. Guineafowl puffer ...

'') grazing on the polyps. The snapping or pistol shrimp (''

Alpheus deuteropus ''Alpheus deuteropus'' or the petroglyph shrimp is a snapper or pistol shrimp in the family Alpheidae. It lives on coral reefs in tropical parts of the Indian and Pacific Oceans and in the Red Sea, as a commensal of corals such as '' Porites loba ...

'') is a

commensal Commensalism is a long-term biological interaction (symbiosis) in which members of one species gain benefits while those of the other species neither benefit nor are harmed. This is in contrast with mutualism, in which both organisms benefit fro ...

and lives among the lobes where it may form grooves and tunnels.

Threats

''Porites lobata'' is one of the more resilient species of coral. A rise in sea temperature may kill the zooxanthellae and cause bleaching, however, it is more resistant to bleaching than many corals and if bleaching does occur, it often recovers. Tropical reefs in general are under threat from many causes. These include El Nino events,

ocean acidification Ocean acidification is the reduction in the pH value of the Earth’s ocean. Between 1751 and 2021, the average pH value of the ocean surface has decreased from approximately 8.25 to 8.14. The root cause of ocean acidification is carbon dioxid ...

which tends to dissolve the coral skeleton,

trawling Trawling is a method of fishing that involves pulling a fishing net through the water behind one or more boats. The net used for trawling is called a trawl. This principle requires netting bags which are towed through water to catch different spec ...

which results in mechanical damage to reefs, and coral diseases which kill the polyps. Due to the lack of coloration, this coral is very rarely collected for use in the aquarium hobby.

References

{{Authority control Poritidae Cnidarians of the Indian Ocean Cnidarians of the Pacific Ocean Corals described in 1846 Taxa named by James Dwight Dana