How coral is formed

by Preeti Sharma

Actually, Coral is a substance formed by the skeletons of the sea animals. It may look like a multi color rock, but it is not. Coral is a living animal and belongs to the large group of animals that comprises of, jelly fish, sea anemones and hydroids.

Coral is a colorful rock found underwater that is used for jewelry extensively. With their bright color range and nice quality, coral jewelry is appreciated throughout the world. You may admire the coral jewelry or may be proud of owing one, but have you ever thought how coral is formed. Not yet? So read on here to know the unique way how coral is formed.

image courtesy: National Geographic

What is Coral?

Actually, Coral is a substance formed by the skeletons of the sea animals. It may look like a multi color rock, but it is not. Coral is a living animal and belongs to the large group of animals that comprises of, jelly fish, sea anemones and hydroids. Corals ooze out a tough skeleton of limestone or calcium carbonate as protection for the coral Polyps.

Live coral animals make a colony of individual Polyps. Each polyp makes a strong and hard skeleton that as a shape like a cup. It is known as calyx that is made for security and support. The skeleton is connected to the polyps around it. Therefore, the skeletons of hundreds coral polyps dwell together forming one coral colony.

Corals are the sea animals that belong to the group of the Phylum Cnidaria with tentacles and stinging cells, also called nematocysts. They have a single opening in their body for the passing of food and waste. The living and healthy coral is colored brightly often.

There are diverse coral formations that look like large domes, branching trees, small irregular crusts, or tiny organ pipes. The living coral forming animals color the formations in beautiful hues of tan, orange, yellow, and green. The coral animals cannot live in cold water below 65 ° F. This is the reason why coral reefs are found in shallow and tropical seas, mostly.

Polyps

The polyps are little carnivorous or meat eating animals that live in millions of number together. The polyps live together in large groups that are called colonies. The polyp is actually related to anemone. It consists of stomach and has a mouth at one end. The mouth is encircled by a good number of tentacles that are similar to feet. The polyp word is related to this fact actually, as in Greek the ‘Polyp’ word meaning ‘many feet’.

The tentacles of polyps are well covered with small stinging cells. So when a small animal gets close and brushed against the tentacles, it gets killed. The prey then goes off to the stomach and is digested. Polyps are immovable from their homes made of limestone. They come out at night to feed most of the time.

So, how do polyps form coral?

The colony of coral grows by the budding of a single coral polyp that splits in two. It makes a matching copy of itself. Most of the polyps that make coral live together in colonies. The polyps attach themselves together with each other. There is a flat sheet of tissue that joins one polyp to the middle of the body of another polyp. The half of coral polyp stretches out above, while the remaining half is down under the connecting sheet.

Continuously the polyps keep on creating the new skeletons at their bottom and sides. While doing this, they keep on going upwards and outwards from coral colony center. The coral polyps take away calcium present in the sea water and make their own limestone skeletons. In this way, they deposit limestone or calcium carbonate in the half region of their lower body halves.

As the polyps die, they go away as limestone skeletons. These skeletons in future become the base of various barriers and ridges that are known as Coral Reefs. The living polyps live on the top of the old and dead skeletons that they have made. In this way the whole colony continues to grow, with the new polyps getting created and the old ones dying off. As there are new polyps growing, the group makes the limestone structure large and larger.

The major part of the structure of single coral colony is actually made up of the dead skeletal material. A living and healthy coral has just a thin layer of living material that inhabits its surface.

How do polyps reproduce?

A coral polyp actually reproduces in using either of the two following ways:

* One way can be to divide its own body to make two polyps

* The other way is to produce sperm and eggs

The eggs and sperm come out from coral polyps at the time just after the full moon in the month of November. They keep floating for about a few days. There are a small number of eggs that get fertilized, originate into larvae and then get settled on the reef. Once they get settled, they start together to begin new colonies. The colonies formed by polyps grow fast. You may be amazed to not e the fact that in three years one polyp can make a colony of 25,000 polyps!

Coral reefs

A strip of curdled coral at or close to the surface of ocean is known as coral reef. The coral reefs are made mostly of coral colonies. They are formed by the animals or plants that grow within them, largely the stony corals. Reefs have a history and life span of about more than about 450 million years on earth. The big coral groups have round or branching masses. Over thousands of years the accumulation of skeletal material forms a coral reef.Coral reefs generally grow in low tropical water. They have algae that need light and they grow sound only near the surface of clear water. Also echinoderms, molluscs, protozoa, sea cucumbers and sponges add to the budding reef. The mats of blue and green bacteria work to ambush and alleviate the structure. Some reefs also have sea grasses and mangroves growing on top of them. As the corals break surface of water they make the coral islands.

Coral reefs are of four types, mainly:

The fringing reefs around islands
The barrier reefs near the landmass, for example the Great Barrier Reef of Australia
The atolls that are actually hollow rings, formed on underwater volcanoes, like the islands of Bermuda
The patch reefs are tiny circular and uneven reefs that rise from the floor of the lagoon or inside the atoll.

Now that you know about how coral is formed, are you a bit more interested in coral jewelry?

Coral in History

by Preeti Sharma

The Tabulate corals, arranged in tabular form, occurred in lime stones and calcareous sedimentary rock of the Ordovician (from 500 million to 425 million years ago) and Silurian (From 425 million to 405 million years ago) periods. They often formed low cushions or branch masses along the side of Rugose corals.

Interested in jewelry made of coral? Then we are sure you will be also interested to know coral in history. How coral was developed in the past? How coral was used in the earlier days in jewelry and lot more. Come on and join this exciting exploration of coral in history.

Geological History of Coral

Corals are first thought to be appeared in the Cambrian period. It was about 570 million years ago. Till the Ordovician period (from 500 million to 425 million years ago), corals were considered extremely rare fossils. Ah this time, Rugose and Tabulate corals were widely popular and became widespread.

The Tabulate corals, arranged in tabular form, occurred in lime stones and calcareous sedimentary rock of the Ordovician (from 500 million to 425 million years ago) and Silurian (From 425 million to 405 million years ago) periods. They often formed low cushions or branch masses along the side of Rugose corals.

In the middle of Silurian period, the number of these corals started to decline. Finally, they became no extant at the end of the Permian period (From 280 million to 230 million years ago). Gradually, the skeletons of Tabulate corals were compiled up in the form of calcium carbonate, called as Calcite.

The Rugose corals were dominant in existence by the middle of the Silurian period. But slowly they also became extinct early in the Triassic period (from 230 million to 190 million years ago). The Rugose corals were found either in lone or in colonial settings. They were similar to the Tabulate corals and their skeletons were also composed of calcite. Most of the all right details of the skeletal structures are well preserved often. These fossils can be cut and polished for further use.

Scleractinian corals can be diversified during the Mesozoic (from 230 million to 63 million years ago) and Cenozoic eras (approximately the last 63 million years). They are at the height of development these days. The fossils can be found in small number in rocks from Triassic period. Relatively, they were common fossils in rock from Jurassic and Cretaceous periods as well as Caenozoic era. Scleractinian corals’ skeletons that are composed of a figure of calcium carbonate known as Aragonite. Scleractinian coral are quite younger geologically as compared to the Tabulate and Rugose corals. The Scleractinian corals, aragonite skeleton are not preserved well and are often easy to get fossils of more old Tabulate and Rugose corals.

It is found in studies that in the geological past, the corals were found abundantly, just like modern-day corals are found in the clear, warm and tropical waters of some particular part of the world today. The modern corals have fossil ancestors that make reefs deep under the ancient seas. There are some coral reefs that lie in the form of great structures amidst sedimentary rocks.

The ancient reefs are not made completely of corals. The algae and sponges and fossilized remains of echinoids, brachiopods, bivalves, gastropods, and trilobites that were on the reefs contributed to make them. The fossil coral reefs are the prime locations to see the different types of fossils, besides corals.

Corals are not limited to reefs only. There are several lonely corals that can be found in rocks where reefs are not present. The geologists have actually been able to date the age of the rocks in which they are found. It is particularly in the case of corals found in limestone of Carboniferous period.

Coral Jewelry in Different Countries Through The Years

The coral beads and artifacts are discovered in the graves of pre dynastic Egypt, dating back to as far as 4000 B.C. They are also found in the graves from Iron Age and Neolithic sepulchers from 10,000 B.C. All through the world, the museums have the collections of amulets and ornaments made of coral belonging to the period of 1000 B.C.

The most ancient and traditional center to fashion coral is Torre del Greco, located near Naples. It was made by the King of Naples in 1870 and Robert Phillips, the jeweler of Cockspur Street London, got a decoration for services for the trade of coral. This can tell best about the popularity of coral jewelry in Victorian England times.

Napoleon had a sundry taste for all Italian things, which acclaimed fashion for carved coral jewelry. The rose pink type of coral was the most sought after fashioned with flowers, especially with roses, cherubs, grotesque masks, chrysanthemums, leaves and fruit. In the early Victorian period, people wore the carved coral charms attached with formed clasps, tiny gold rings, decorated cuffs and other stylish jewelries.

During the 1860’s, the coral beads and ovoid were arranged in gold brooches. In the 1870’s, people had coral in flowered gold brooches, in combination with diamonds and emeralds. It was unfortunate that gradually exposed so much with popularity and overuse, coral was declined in Victorian jewelry. Particularly in the so called proper circles, coral was considered to be vulgar. Towards the end of the 19th century, coral was rarely used in jewelry.

The period of 1920’s and 1930’s observed resurgence and proved as an enhancement to the geometric forms prevalent in that period. But once again, it started to decline until the 1970’s.

To talk about the use of coral in some particular countries-In India, coral had a high value and was often ornamented in the figures of gods. Same was the traditional use of coral in China, while the in Persia its color was mostly admired. The Tibetans consider the red coral to be symbolic of one of the avatars or incarnations of Buddha. The use of coral was highly prevalent in the 13th century that the famous traveler and historian Marco Polo also mentioned about it.
In Africa, coral was worshipped in the ancient days. It was considered as the most invaluable gift that the ruler could bestow on people. Over a long period in past now, people all over the world have kept on taking delight in coral. The Renaissance and the Victorian periods assimilated it in the fine jewelry designs.

What else we can tell about the importance of coral in history-American President Lincoln was highly fond of it; Europe witnessed shrewd rivalries for coral; since medieval to the present times, countries like Europe and Mediterranean have competed to be in charge of the coral fishing rights on the African coasts.

After completing a long journey in history, coral is today available in the designs of earrings, rings, cameo brooches and necklaces and will continue to rule over the jewelry lover’s hearts.