×

Warning

Please Login to Read More...

Life in the ocean starts with coral reefs!
Coral reefs

To see some of the planet's most picturesque scenery, we need to take a trip below sea level! Coral reefs are among the greatest natural wonders of the world's oceans. They come in a seemingly infinite array of shapes and colors and teem with life. Often called "rainforests of the sea", coral reefs are among the Earth's most diverse ecosystems, and the world's largest single structure made by living organisms. Teeming with life, these economically and environmentally important ecosystems provide a home for many unique marine organisms. Scientists previously looked toward plants for medicinally potent compounds; coral reefs are now receiving much attention as an untapped pharmaceutical resource. It is therefore of the utmost importance that we protect coral reefs, both to prevent extinction and discover new medicines.

How are these incredible structures created? How can a single coral that is only 3 millimeters long become a reef that may stretch for miles and weigh hundreds of tons? Let's read on to know how this incredible coral reefs form, what kind of life they harbor and why scientists say in future, coral reef ecosystems could represent an increasingly important source of medical treatments, nutritional supplements, pesticides, cosmetics, and other commercial products.

Coral polyps — Tiny builders.  Coral reefs are built by and made up of thousands of tiny animals – coral "polyps" – that are related to anemones and jellyfish.
What are coral reefs?

What exactly is coral? Coral is a colony of animals that live together within a common skeleton. A reef may consist of billions of individual animals called coral polyps. Each individual coral animal is called a polyp, and most live in groups of hundreds to thousands of genetically identical polyps that form a 'colony'. The colony is formed by a process called budding, which is where the original polyp literally grows copies of itself. Each polyp has tentacles (to feed on phytoplankton), a mouth, stomach, and algae (plants) that live inside of it. The algae are called Zooxanthellae. The "animal part" of the coral polyp provides waste material and CO2 for the algae. In turn, the coral may use food and oxygen produced by the algae. Corals extract abundant calcium from surrounding seawater and uses this to create a hardened structure for protection and growth. Coral reefs mainly consist of shells of aragonite, one of two naturally occurring crystalline forms of calcium carbonate (CaCO3). The corals themselves secrete these shells while maintaining a symbiotic relationship with small algae called zooxanthellae that live on the surface of the coral and give them their vibrant color.

Thus, coral reefs are constructed by number of tiny polyps forming large carbonate structures, and are the basis of a framework and home for hundreds of thousands, if not millions, of other incredible and colorful species. Coral reefs are the largest living structure on the planet, and the only living structure to be visible from space.

Corals get nutrition from zooxanthellae, living within their tissue
How coral reefs work?

The sun is the source of energy for the coral reef ecosystem. Plant plankton, called phytoplankton, algae and other plants convert light energy into chemical energy through photosynthesis. As animals eat the plants and other animals, energy is passed through the food chain. Reef building corals work together with microscopic algae, called zooxanthellae, that live in their tissue. The zooxanthellae provide oxygen and food to the coral through photosynthesis. The coral polyp gives the algae a home, and the carbon dioxide it needs through respiration. Besides zooxanthellae, algae and seagrasses are the main types of plants in the coral reef ecosystem. These plants give food and oxygen to the animals that live on the reef.

This symbiosis between plant and animal not only benefits each other but also contributes to the brilliant colors of coral that can be seen while diving on a reef. Thus, photosynthesizing plants and algae convert light energy into chemical energy, which then gets passed through the food web to plant eaters, flesh eaters, and ultimately to scavengers and decomposers.

Their brilliant color comes from the zooxanthellae pigments living inside their tissues. 
Why coral reefs are colorful?

Their wide range of colors is caused by a number of factors, including life that inhabits them and environmental conditions. Coral reefs derive their unique and fascinating coloring from organisms living within their structure. These organisms are known as zooxanthellae (we discussed its photosynthetic activity in the previous paragraph). In addition to providing corals with essential nutrients, zooxanthellae are responsible for the unique and beautiful colors of many corals. Several million zooxanthellae live and produce pigments in just one square inch of coral. These pigments are visible through the clear body of the polyp and are what gives coral its beautiful color. Sometimes when corals become physically stressed, the polyps expel their algal cells and the colony takes on a stark white appearance. This is commonly described as "coral bleaching". If the polyps go for too long without zooxanthellae, coral bleaching can result in the coral's death. Thus, it's merely the amount or lack of zooxanthellae that controls coral coloration.

Some corals increase the production of colorful protein pigments when they are exposed to more intense sunlight. Humans get a sun tan, similarly, corals become more colorful. The brownish appearances of many corals under daylight are due to photosynthetic pigments from the microscopically small plants that live in symbiotic partnership within them. But most of the green, red and purple-blue hues are caused by a family of protein pigments, called fluorescent pigments (FPs). Some coral pigments glow green or red under ultra-violet or blue light, a physical phenomenon called fluorescence. Hence, the incredible colors of corals!

Coral reefs are often considered the medicine cabinets of the 21st century. Coral reef plants and animals are important sources of new medicines being developed to treat cancer, arthritis, human bacterial infections, Alzheimer's disease, heart disease, viruses, and other diseases.
Why are coral reefs so important?

It's true—these colorful and sometimes crazy-looking underwater structures host a lot more than just cool sea creatures.  From the first polyp to the complex ecosystems they have become today, coral reefs support innumerable life above and below the water. As a marine ecosystem, coral reefs are the most diverse and productive habitat supporting a quarter of all marine species. Above water, coral reefs bring value to communities, and humans, in the form of employment, sustenance, and wonder.

Coral reefs could hold the cures for some of the human race's most common and most serious ailments. Scientists have already developed many medical treatments from resources found in the world’s oceans. There are already coral reef organisms, enzymes, and algae which are used to treat asthma, arthritis (Secosteroids, an enzyme used by corals to protect themselves from disease, is used to treat asthma, arthritis and other inflammatory disorders), and even types of cancer (Blue-green algae, commonly found in Caribbean mangroves, are used to treat small-cell lung cancer. The National Cancer Institute also endorsed blue-green algae for the treatment of melanoma and some tumors). A series of organic chemicals isolated from a soft coral called the Caribbean sea whip seem to have an impressive anti-inflammatory effect on human skin. Bioactive molecules produced by marine invertebrates such as sea sponges, tunicates and sea hares have displayed potent anti-viral, anti-tumor and antibacterial activity.

This is a developing field and protecting coral reef means protecting these future discoveries. Thus, coral reefs have intrinsic value to life and priceless inspiration and discoveries for the future. It's time we start looking closer at corals and appreciating nature's incredible gift.

References

  • https://communities.acs.org/community/science/sustainability/green-chemistry-nexus-blog/blog/2013/02/13/chemistry-and-coral-reefs-bleaching-and-greening
  • https://www.icriforum.org/about-coral-reefs/what-are-corals
  • https://www.ncbi.nlm.nih.gov/pubmed/11130722