The open brain corals, Trachyphyllia geoffroyi, are just one of thousands of classifications 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...

. They are named as such due to their resemblance to an inverted animal brain

Brain

The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...

 as seen by the human eye. As the name also suggests, the open brain corals are related to the many other species of brain coral

Brain coral

Brain coral is a common name given to corals in the family Faviidae so called due to their generally spheroid shape and grooved surface which resembles a brain...

s found in shallow warm-water coral reefs in all the world's ocean

Ocean

An ocean is a major body of saline water, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas.More than half of this area is over 3,000...

s. The different specific sub-species come in an array of colors ranging from opaque, blue, green, red, and brown.

Habitat

Open brain corals are found in the warm, shallow waters of the tropics

Tropics

The tropics is a region of the Earth surrounding the Equator. It is limited in latitude by the Tropic of Cancer in the northern hemisphere at approximately  N and the Tropic of Capricorn in the southern hemisphere at  S; these latitudes correspond to the axial tilt of the Earth...

. Due to the symbiotic relationship corals have with zooxanthellae (for more information, see "symbiotic relationship" section), corals and therefore coral reefs, thrive in clear, shallow waters to allow the zooxanthellae to photosynthesize

Photosynthesis

Photosynthesis is a chemical process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs, since they can...

. However, this general rule does not apply to all species and there are some exceptions.

Although specific species of open brain corals can be found in all of the world's oceans, they are predominately found in the Indian Ocean

Indian Ocean

The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...

 including the Red Sea

Red Sea

The Red Sea is a seawater inlet of the Indian Ocean, lying between Africa and Asia. The connection to the ocean is in the south through the Bab el Mandeb strait and the Gulf of Aden. In the north, there is the Sinai Peninsula, the Gulf of Aqaba, and the Gulf of Suez...

, and throughout the coastal waters of Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

. The sediment

Sediment

Sediment is naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself....

 types that the open brain corals thrive on are sandy to silt

Silt

Silt is granular material of a size somewhere between sand and clay whose mineral origin is quartz and feldspar. Silt may occur as a soil or as suspended sediment in a surface water body...

y bottoms.

Structure

Open brain corals, like most other corals, are composed of colonies of genetically identical, anemone

Anemone

Anemone , is a genus of about 120 species of flowering plants in the buttercup family Ranunculaceae in the north and south temperate zones...

-like polyps. These polyps secrete calcium carbonate

Calcium carbonate

Calcium carbonate is a chemical compound with the formula CaCO3. It is a common substance found in rocks in all parts of the world, and is the main component of shells of marine organisms, snails, coal balls, pearls, and eggshells. Calcium carbonate is the active ingredient in agricultural lime,...

 to create a exoskeleton

Exoskeleton

An exoskeleton is the external skeleton that supports and protects an animal's body, in contrast to the internal skeleton of, for example, a human. In popular usage, some of the larger kinds of exoskeletons are known as "shells". Examples of exoskeleton animals include insects such as grasshoppers...

 that protects the body of the polyp. When the individual exoskeletons fuse together to construct a colony, they create a skeleton base for the coral as a whole. If all of the polyps in the colony should die, the calcium skeleton of the coral will be left behind. These calcium skeletons are commercially sold as souvenir

Souvenir

A souvenir , memento, keepsake or token of remembrance is an object a person acquires for the memories the owner associates with it. The term souvenir brings to mind the mass-produced kitsch that is the main commodity of souvenir and gift shops in many tourist traps around the world...

s around the world.

Food

Open brain corals are nocturnal feeders and extend their stinging tentacles only in the evening and night hours. They do so to filter zooplankton

Zooplankton

Zooplankton are heterotrophic plankton. Plankton are organisms drifting in oceans, seas, and bodies of fresh water. The word "zooplankton" is derived from the Greek zoon , meaning "animal", and , meaning "wanderer" or "drifter"...

, phytoplankton

Phytoplankton

Phytoplankton are the autotrophic component of the plankton community. The name comes from the Greek words φυτόν , meaning "plant", and πλαγκτός , meaning "wanderer" or "drifter". Most phytoplankton are too small to be individually seen with the unaided eye...

 and any small organism that swims in the surrounding water to feed upon. Open brain corals are able to feed upon organisms such as small fish because the individual polyps work together to catch the pray with their stinging tentacles.

Symbiotic relationship

Open brain corals, along with other species of corals, have a symbiotic relationship with zooxanthellae. One cell of algae lives within each polyp of the coral and gives off valuable nutrients such as oxygen

Oxygen

Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

to the coral. This relationship between the corals and algae is symbiotic because both parties involved benefit from the relationship. The algae is given a protected place inside the coral to live and the coral receives nutrients it needs to survive from the algae.

Aquarium life

Open brain corals have become increasingly popular among saltwater aquarium enthusiasts. They are said to be one of the easiest species to care for and has a high rank in terms of hardiness. Many aquarium experts suggest the open brain coral for beginners to put in their first aquarium.

Open brain corals come in a variety of colors but the colors most commonly found in the aquarium industry are the fluoresce blue, green, red, and opaque. In these captive environments, open brain corals usually grow to approximately eight inches in diameter.