Shedd: The World's Aquarium logo

Lesson Plans
Interactives
Explorer's Guide
The Exterior of John G. Shedd Aquarium
EDUCATION
JOIN OR CONTRIBUTE
CONSERVATION PLAN A PRIVATE EVENT
 

The Explorer's Guide contains a treasure trove of aquatic science resources developed for use in K-12 classrooms. Back to Explorer's Guide.


Brain Coral Scientific Name: Lobophyllia sp.
These corals get their name from their strange similarity to the human brain with their maze-like grooved surface. This pattern is actually made of tiny animals called coral polyps. Thousands of polyps make up the entire coral colony or coral head.



Region: Philippines


Appearance
Sturdy, massive corals like the brain corals grow so slowly that they take hundreds of years to reach their enormous size. They can grow to be as large as 7 feet (2 m) around. The shape of the entire colony is either flat or encrusting, and most often a perfectly round mound. Brain corals come in a variety of colors—green, purple, yellow, orange, red, and blue. They usually all have white tips on the ends of the polyps.

The compact surface of brain corals means they need a fair amount of light. They have zooxanthellae or algae that live just under the skin of the coral. The tiny algae and the coral have a symbiotic relationship or partnership needed for survival. The algae make food for the coral using the energy from the sun. The algae feed off the coral’s waste. The coral gives the tiny algae oxygen and a safe place to live.

The polyp skeletons are so large that they may even be called valleys. They are different from most other round skeletons. Brain coral skeletons snake around the coral head in shapes of jelly beans, half moons and squiggles.

The polyps are nocturnal or active at night. They are very long and are one of the most aggressive of all the corals. On the skin of the polyps are mesentary filaments, which extend from the skin and secrete juices that digest any animals near the brain coral. This form of attack is very important for these slow growing corals. They are always in danger of other quick growing corals overgrowing them and blocking out the sunlight they need for their zooxanthellae. These filaments look like thin, clear arms and can reach pretty far. The brain corals also use their mesentery filaments to catch food when they are hungry.


Habitat
Massive corals like the brain corals stand up to strong currents and wave action in shallow water areas. They are usually found on the upper reef slopes and in lagoons.


Range
Brain corals live in the warm parts of the Pacific Ocean, Indian Ocean and Red Sea.


Diet
Like all animals, corals need food. Sweeping the sea with their tentacles, coral polyps eat zooplankton or tiny animals and phytoplankton or tiny plants, which drift on ocean currents. Nematocysts or stinging barbs inside cells on a polyp’s tentacles harpoon plankton, and then fine hairs and mucus carry it to the animal’s mouth.

These corals get the majority of their nutrition from their zooxanthellae though.


Reproduction
Just like other animals, corals reproduce sexually. Because polyps can’t move to meet mates though, they release eggs and sperm into the water. Releasing of the eggs and sperm is often triggered by a full moon when the ocean waters begin to warm in the spring or summer. After releasing millions of brightly colored eggs and smoky-looking clouds of sperm, they unite and grow into tiny larvae. The larvae are left on their own to swim off and establish new colonies, often many miles from the parent reef.

Besides forming new colonies through sexual reproduction, corals can form new colonies in other ways. Sometimes rough weather breaks off a piece from an existing colony. If that fragment resettles, it may continue to grow as a new colony. This process is called fragmentation. They can form new colonies through asexual reproduction or to make an exact copy without eggs and sperm. By budding, coral polyps divide to create new individuals. As more polyps bud, a colony grows.


Endangered
>A species or group of organisms that is in danger of extinction or disappearing from the face of the earth in the near future if its situation is not improved.

Threatened
A species that can be found throughout its natural range but is declining in number and may become endangered in the absence of special protection efforts.

Vulnerable
A species that is not declining in number but is of special concern because it is sensitive to pressure by particular human activities or natural events.

Stable
A species that is not declining in number and is not sensitive to pressures by human activities or natural events.

Back to top


Threats and Management
Living on a coral reef can be stressful. They are not only affected by natural threats, but also by stresses caused by people. Reefs can rebound from short-term stresses, returning to their natural state soon after. After they are subjected to long term stress, especially when caused by people, entire reef ecosystems may die. Some of these stresses include poisoning or smothering from farm and factory chemicals or sewage, or damage from more people visiting the reef. These activities can be especially stressful for slow growing brain corals. Many countries around the world that are surrounded by corals reefs have made laws to protect these natural resources. These laws have helped to keep the population of brain corals stable.


Did You Know?
Scientist can tell the age of a coral by looking at bands on the skeleton—just like the rings you can see on a tree trunk.


References
Print Publications:
Allen, G. R. & Stene, R. 1996. Indo-Pacific Coral Reef Field Guide. El Cajon, California: Odyssey Publishing Company. 378p. ISBN# 981-00-5687-7.

Banister, K. & Campbell, A. 1988. Encylopedia of Aquatic Life. New York, New York: Equinox (Oxford) Ltd. 349p. ISBN# 0-8160-1257-101-X.

Colin, P. L. & Arneson, C. 1995. Tropical Pacific Invertebrates. Beverly Hills, California: Coral Reef Press. 296p. ISBN# 0-9645625-0-2.

Perrine, D. 1997. Mysteries of the Sea. Lincolnwood, Illinois: Publications International, Ltd. 312p. ISBN# 0-7853-2430-5.

Reader’s Digest. 1984. Reader’s Digest Book of the Great Barrier Reef. Sydney, Australia: Reader’s Digest Services Pty Limited. 384p. ISBN# 0-949819-41-7.

Veron, J. 2000. Corals of the World. Volume 3. Townsville, Australia: Australian Institute of Marine Science. 490p. ISBN# 0-642-32238-4.


Back to top


Vocabulary Words

Asexual Reproduction – Reproduction that does not involve the union of egg and sperm; results in an exact copy of the original animal.


Budding – When a coral polyps divides to create a new individual. As more polyps bud, a colony grows.


Extinction – An organism that has not been present on the face of the earth for over 50 years.


Fragmentation – The process through which a new coral colony forms when a piece breaks off an existing colony, resettles on a new area of the reef, and starts to form a new colony.


Hard coral – The members of the order Scleractinia, which secrete a heavy, external, calcareous skeleton, and many of which are primary contributors to the building of coral reefs.


Mesentary filaments – Extensions of a corals skin that secrete digestive enzymes that dissolve living tissue. This tissue is used for defense and feeding.


Nematocyst – Stinging barbs like tiny harpoon-like stingers which deliver a paralyzing poison sting to stun or kill prey.


Nocturnal – Active at night.


Organism – A living thing.


Pet trade – An industry or business in which animals are taken from the wild and sold to pet stores, zoos, and aquariums.


Phytoplankton – Microscopic plants that float at the mercy of the ocean currents.


Polyp – An animal that does not move because it is attached to a hard substrate; resembles a flower with the bottom of its stalk attached to a stable surface and tentacles and oral arms facing upward; reproduces asexually.


Species – A group of organisms capable of breeding and producing fertile offspring; organisms that share the same gene pool.


Symbiotic relationship – Symbiosis – In order to survive, certain creatures form partnerships with other kinds of animals or plants for feeding, housing or protecting one another.


Zooplankton – Microscopic animals that float at the mercy of the ocean currents and have weak swimming ability.


Zooxanthellae – Tiny single-celled algae called dinoflagellates that have a symbiotic relationship with an organism like the giant clam or corals. In exchange for a safe place to live under the organism’s skin, the zooxanthellae provides its host with nutrients it makes using the sun.


Back to top

CHOOSE A LANGUAGE
English Español



CONTENTS:

Emerald brain coral (Lobophyllia hataii) Copyright Shedd, Edward G. Lines
Emerald brain coral (Lobophyllia hataii) Copyright Shedd, Edward G. Lines

Radiant brain coral
Copyright John G. Shedd Aquarium

©2001-2006 John G. Shedd Aquarium   Home   Contact Us   Site Map   Help   FAQ   Jobs and Volunteering   Terms of Use