Madrepora oculata, also called zigzag coral, is a Scleractinia

Scleractinia

Scleractinia, also called stony corals, are exclusively marine animals; they are very similar to sea anemones but generate a hard skeleton. They first appeared in the Middle Triassic and replaced tabulate and rugose corals that went extinct at the end of the Permian...

 (stony coral) that is found worldwide outside of the polar regions, growing in deep water

Deep water coral

The habitat of deep water corals, also known as cold water corals, extends to deeper, darker parts of the oceans than tropical corals, ranging from near the surface to the abyss, beyond where water temperatures may be as cold as 4°C...

 at depths of 80–1500 meters. It was first described by Linnaeus in 1758. It is one of only 12 species of coral

Coral

Corals are marine animals in class Anthozoa of phylum Cnidaria typically living in compact colonies of many identical individual "polyps". The group includes the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton.A coral "head" is a colony of...

 that are found worldwide, including in Subantarctic

Subantarctic

The Subantarctic is a region in the southern hemisphere, located immediately north of the Antarctic region. This translates roughly to a latitude of between 46° – 60° south of the Equator. The subantarctic region includes many islands in the southern parts of the Indian Ocean, Atlantic Ocean and...

 oceans. In some areas, such as in the Mediterranean Sea

Mediterranean Sea

The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by North Africa, and on the east by the Levant...

 and the North-east Atlantic Ocean

Atlantic Ocean

The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...

, it dominates communities of coral.

Description

The species is quite variable in its tendency to branch, its texture and color and other aspects, even within specimens in the same coral colony. It is bushy, growing in small colonies that form thickets, creating matrices that are fan-shaped and about 30 to 50 cm high. It has thick skeletal parts that grow in a lamellar pattern. As its skeleton is fragile and unable to sustain a large framework, it is usually found among stronger coral, such as Lophelia pertusa

Lophelia pertusa

Lophelia pertusa is a species of cold-water coral which grows in the deep waters throughout the North Atlantic ocean, as well as parts of the Caribbean Sea and Alboran Sea. L...

and Goniocorella dumosa, that offer protection. In areas where it dominates, it is usually found in rubble and debris rather than in coral reefs.

Madrepora oculata produces large amounts of mucus

Mucus

In vertebrates, mucus is a slippery secretion produced by, and covering, mucous membranes. Mucous fluid is typically produced from mucous cells found in mucous glands. Mucous cells secrete products that are rich in glycoproteins and water. Mucous fluid may also originate from mixed glands, which...

 that is extracellular

Extracellular

In cell biology, molecular biology and related fields, the word extracellular means "outside the cell". This space is usually taken to be outside the plasma membranes, and occupied by fluid...

 or outside the cell membranes. The mucus acts in a protective capacity to shield the coral skeleton from attacks of destructive pests.

Hypertrophy

The first instances of seeming neoplasms in a coral were reported in a species of Madrepora in Hawaiian waters in which hypertrophied

Hypertrophy

Hypertrophy is the increase in the volume of an organ or tissue due to the enlargement of its component cells. It should be distinguished from hyperplasia, in which the cells remain approximately the same size but increase in number...

 corallites or skeletons in the coral were noted. Similarly hypertrophied corallites were described in colonies of Madrepora oculata near northwestern Australia and Japan, as well as in the Formosa Strait and other areas, but have never been confirmed. A recent provisional reinterpretation is that these abnormal corallites are a form of internal gall

Gall

Galls or cecidia are outgrowths on the surface of lifeforms caused by invasion by other lifeforms, such as parasites or bacterial infection. Plant galls are abnormal outgrowths of plant tissues and can be caused by various parasites, from fungi and bacteria, to insects and mites...

, an abnormal swelling or growth caused by infection by a parasite

Parasitism

Parasitism is a type of symbiotic relationship between organisms of different species where one organism, the parasite, benefits at the expense of the other, the host. Traditionally parasite referred to organisms with lifestages that needed more than one host . These are now called macroparasites...

, rather than a neoplasm caused by mutation.