Coral reefs support up to 25% of all marine life on the planet. Corals are animals, not plants, even though they are rooted to the ocean floor or rocks. Many people think of corals as plants, but they actually consist of tiny animals called Cnidarians that are only a fraction of an inch in diameter. In most cases corals consist of a central polyp surrounded by a hard exoskeleton. But there are also soft corals too, that have no exoskeleton at all. These amazing creatures occupy less than 0.1% of the world’s ocean area (about 1/2 the area of France). However, they provide a safe haven for at least 1/4 of all marine species. Sadly, climate change and pollution have drastically impacted coral reefs and the lives therein.
First the Stats…
Scientific name: Varies by type of coral
Weight: Varies by type of coral
Length: Varies by type of coral
Lifespan: Varies by type of coral
Now on to the Facts!
1.) Flourishing in ocean waters that provide few nutrients, they can frequently be found at shallow depths in tropical waters. However, deep water and cold water coral reefs exist on a smaller scale in other regions.
2.) Coral reefs have changed little since their inception back when dinosaurs ruled the earth; around 230 million years.
3.) Reef structures can grow so large that they can be seen from outer space!
4.) The plants and animals that live on and around reefs have a symbiotic relationship, in that they rely on one another for survival.
5.) The Great Barrier Reef is thought to be the largest structure ever constructed by animals.
But wait, there’s more on the coral reefs!
6.) Reefs also help humans in a various ways. 1 way is that they help the tourism business, due to all the people that flock to various reefs to scuba dive and snorkel to view the reefs and subsequent marine life. This helps finance communities.
7.) Another way reefs help humans is that they form a natural barrier for the ocean’s currents and help to slow down erosion on beaches.
Did you know…?
Corals grow very slowly at an average of up to .39 inch of height, per annum. This equates to an average of just a few miles of growth per million years.
8.) Polyps are typically adhered to the substrate in which they grow, using a pedal disc that bores into the hard stratum. As they grow, they secrete calcium carbonate that forms an external shell. Over millions of years, this hard exoskeleton develops to form a coral. Polyps reproduce to form planulae that increase the overall coral reef coverage.
9.) Fringing reefs (shore reefs) – They grow close to the shore and thrive in shallow water. Red Sea Corals are an example.
10.) Platform reefs – These are wider towards the top and are closer to the sea bed. They grow on the continental shelf, further away from the coastline. Platform reefs create lagoons in the middle of the open ocean and are found within atolls.
But wait, there’s still more on the coral reefs!
11.) Atolls – An atoll is a circular shaped coral reef that contains a lagoon in the middle. Over millions of years, these islands gradually erode below the water’s surface, as the corals continue to grow. This develops a ring of corals and a subsequent lagoon. Atolls can be found in the Pacific and Indian oceans and create various formations like the apron, bank, cays, Guyot, Habili, patch, and ribbon reefs.
12.) Barrier reefs – These reefs develop close to the end of a continental plate. Some famous barrier reefs include: Australia’s Great Barrier Reef, the New Caledonian Barrier Reef, and the Belize Barrier Reef. Barrier reefs develop lagoons that can span hundreds of feet. These reefs are rare and are responsible for developing lagoons near the coasts of the Comoros archipelago, French Polynesia, the Caribbean, New Guinea, Indonesia, and the Louisiade Archipelago.
Did you know…?
The Belize Barrier Reef Reserve System is the second largest reef in the world and helps protect people in the Caribbean from tidal influxes caused by hurricanes.
13.) Successful and healthy coral growth is dependent upon things like water quality and available nutrition; not to mention ample sunlight. If these parameters are met, then coral can easily grow up to 4 inches per year.
14.) Although massive and looking like just 1 huge structure, the Great Barrier reef is actually made up of bout 300 coral reefs and approximately 1,000 islands.
15.) Bleaching is a term used to describe when a coral dies and leaves behind it’s bony, white skeleton. Bleaching is caused by several factors: low tides, pollution, too much sunlight, and the number 1 factor… climate change.
But wait, there’s still a little more on the coral reefs!
16.) Artificial reefs are developed, in part, by intentionally sinking retired water vessels. In time corals and ocean life begin to develop and thrive in this artificial habitat. But maintaining the health of natural reefs is and will always be the best option.
17.) Damage to beaches, due to construction and erosion, can also cause reefs to fail, as silt and dirt muddy the water, preventing sunlight from reaching the corals. It can also cause water pollution, due to foreign chemicals (like pesticides and herbicides) being leached into the water.
18.) Corals are amazing and long lived, but they are also picky about living conditions. They will only grow successfully at certain depths. Water that is too deep doesn’t provide enough sunlight for the symbiotic zooxanthellae that grow in their system to produce enough energy to survive.
19.) After a certain water depth, sunlight is lessened and the Symbiodinium cannot gather enough energy for the polyp through photosynthesis, which results in polyp death and subsequent bleaching.
20.) Through millions of years of evolution, polyps have adapted to grow outwards, rather than upwards. This way they can account for fluctuating water levels and also get the most light possible.
But wait, there’s still a bit more on the coral reefs!
21.) Known as rainforests of the sea, coral reefs harbor an incredible 25% of the ocean’s organisms. This large amount of creatures gathering in 1 place is due to the large amount of refuges (places to hide) that are created in and around the reefs. There is, as a result of so much diversity, a constant exchange of nutrients for organisms big and small.
Did you know…?
The global reef tourism industry brings in up to $36 billion each year!
23.) Corals feed in 2 primary ways: by capturing zooplankton that happen to float near their polyp tentacles, and/or by their symbiotic relationship with zooxanthellae (photosynthetic organisms that require sunlight to live and grow within corals & shares a symbiotic relationship with the polyp).
24.) Zooxanthellae produces nutrients that they share with the polyp, while in exchange the polyp offers protection for the zooxanthellae.
25.) The zooxanthellae come in different colors based on the type of chlorophyll in their cells. As light conditions and temperatures change, zooxanthellae alter their color over a wide spectrum to act as a type of protection against UV rays.
26.) Currents are directly related to the surface temperature of the surrounding water. The faster the current, the cooler the water. So, since corals prefer cooler temperatures, but not colder temperatures, they tend to grow closer to the surface of the water, as this assures them of cool temperatures, which combat the heat of the sun they require to survive.
27.) Typically, most sea creatures do not live in regions with strong currents due to the fact that the water is nearly devoid of nutrients. However, corals thrive in these areas because they feed primarily on plankton and zooplankton which are trapped in the reef.
28.) Due to the wide range of creatures in the reef ecosystem, the reef typically has an unlimited supply of plankton which can be used by different animals. This enigma gave rise to the famous Darwin’s Paradox.
Did you know…?
Darwin’s Paradox describes an anomaly of the ocean and the incredible diversity of coral reefs in the middle of an otherwise stark abyssal plain.
29.) Polyps are sensitive to the tiniest changes in water conditions. Changes such as salinity, pH, temperature, and changes in the concentration of particulate matter can all have adverse effects on corals.
30.) As a result of their sensitivity, they have evolved a sort of built in filtration system. They use tiny sieves that line the coral’s shell that remove particulate matter. This helps to keep the surrounding water cleaner for the other reef inhabitants.
But wait, there’s just a tad more on the coral reefs!
31.) Coral reefs have the ability minimize wave energy by nearly 97%! This means that the dangerous effects of storms and tsunamis can also be mitigated. 1 example of this is seeing the calm water of a lagoon amidst the crashing surrounding waves outside of the lagoon.
32.) Corals are also used in modern medicine. For example, coral shells are used in bone grafting to provide a base for the body to heal difficult fractures.
33.) Certain aspects of corals are also used to treat AIDS and cancer.
Now a Short Coral Reefs Video!
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