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What are Reef Producing Coral

Corals occupy less than 0.1% of the earth's surface. Yet, four types of coral reefs provide various habitats for more than one million fish species and other animals.

This section explains the most pressing problems faced by vulnerable corals with a list of easy ways to help protect and conserve coral reef environments.

Coral Formations: Ecology and Biodiversity

There are two different types of coral, hard stony corals (e.g. staghorn coral) and soft corals (e.g. sea whips).

The biodiverse marine ecosystems created by corals are a habitat for:

Reef producing coral are called hermatypic corals. These reef builders are invertebrate animals that have a rigid calcium carbonate skeleton.

Healthy coral reefs are important for several reasons. They provide food, income (e.g. scuba diving tourism), and coastal protection for more than half a billion people living in coastal regions around the world.

Pro Tip: We often get asked... What is coral, plant or animal? Another segment explains what corals are made of, how these tiny colonial organisms create colourful reef structures, and the difference between hard and soft corals (hermatypic vs. ahermatypic).

4 Types of Coral Reefs

When marine biologists and scientists use words related to sea life, they tend to list four different classifications of coral reef structures.

Atolls

Usually circular or ring-shaped, atolls are small, low lying islands that have a coral rim encircling a lagoon. Often, they are in the middle of the sea and far away from land, such as the Great Blue Hole in Belize, Central America.

Barrier Reefs

For the most part, a barrier reef (e.g. the GBR in Australia) tends to run parallel to the coastline, often separated by a deep or wide lagoon.

Coral Reef Formations: The Importance of Reef Producing CoralsThe shallowest parts of some barrier reefs are visible at the surface of water. This feature often creates a navigational barrier for large ships.

Fringing Reefs

A fringing reef is one that grows quite close to a coastline, especially at the outer edge of islands and continents.

Narrow and shallow lagoons often separate them from the shoreline. The most common type of coral reef is fringing reefs.

Patch Reefs

A patch reef is a small coral reef ecoregion growing upwards - often in isolation - from an open bottom of an island platform or continental shelf. The best place to find a patch reef is between a fringing reef and a barrier reef. They vary in size, but rarely break the surface of the water.

Interesting Fact: New technologies in additive manufacturing, and more specifically 3D printed coral reefs, are helping to create artificial habitats for marine life and support global efforts in coral restoration and regeneration.

Types of Hard Coral Formations

Acropora Millepora

The best place to find these branching stony corals is the western Indo-Pacific, at depths between two and twelve metres (6 to 40 feet).

Yet, the geographical range of Acropora millepora is broad. It exists in the shallow reef flats near the east coast of Africa, Egyptian Red Sea, as far north as Japan, and around the southern shorelines of Indonesia, and Australia.

Characteristics and Colouring

It is a small colonial species with short, cylindrical branches that tend to grow in patches or clumps. Their radial skeletal cups (called corallites) are uniform with scaly lower rims.

Acropora millepora is a colourful species of coral. In general, its branches are dark green with orange tips, or sometimes pink, blue, or green.

Conservation Status

The general destruction of coral reef formations worldwide is the biggest threat to the long term survival of Acropora millepora.

They are quite abundant in some shallow water locations. But, this particular species is susceptible to (all):

Important: The IUCN Red List of Threatened Species assessed Acropora millepora in January 2008. They recorded the species as being Near Threatened (NT) and the population trend is "decreasing".


Acropora Tenuis

It's often described as thin branching coral, but Acropora tenuis are small polyped stony corals belonging with the phylum Cnidaria.

The distinct coral reef formation of Acroporidae is one that develops into comb-like, bushy colonies. Short branches with tapered tips project upwards and interlock together from a corymbose horizontal base and produce an overall appearance of short bushy thickets.

Size and Colour

Unlike many of the robust staghorn corals, such as Acropora robusta, the branches of Acropora tenuis are thin and needle shaped (acicular).

The general colour of this particular species of hermatypic coral is brown, even though symbiotic algae can produce alternative colourations, such as cream, blue, or green.

Range and Habitat

The best places to find Acropora tenuis are the Red Sea, Japan, central Indo-Pacific regions, Southeast Asia (Indonesia, Philippines), Coral Sea, and Australia (the Great Barrier Reef).

This species is more common in clear water where there's plenty of sunlight. It grows a lot faster if there is a good amount of wave action, such as around shallow reef flats, upper reef slopes, and some lagoons.

Conservation Status

These coral reef formations construct corymbose colonies that provide vital shelter for numerous marine invertebrates and a range of small reef fishes.

However, the delicate skeletons of these types of reef polyps often get damaged by the forces of nature, especially strong waves and destructive storm surges.

Pro Tip: In 2023, the IUCN Red List of Threatened Species assessed Acropora tenuis and noted them as being "Endangered" (EN) with a "Decreasing" population trend.


Artichoke Coral (Scolymia cubensis)

If you have a fish keeping hobby, or you go diving around the western Atlantic, you're likely to have seen the vibrant colours of the artichoke coral.

Scolymia cubensis are not colonial corals. Instead, they are a solitary species made up with a large, round fleshy polyp that rarely grows more than fifteen (15) centimetres across (6 inches).

Basically...

The layered shape resembles that of an artichoke, a greenish vegetable with a similar rosette appearance.

For the most part, artichoke corals are various shades of green, reds, and sometimes with purple patterns. They thrive best on rocky reef slopes and sandy bottoms.

Range and Habitat

The best place to find the artichoke coral is the Caribbean side of Central America, especially Bermuda and Jamaica. Typically, the upper depth limit is around ten metres (33 feet), with a lower depth range close to ninety metres (295 feet).

Like many coral formations, it relies on symbiotic zooxanthellae algae for energy via photosynthesis. Plus, they're also known to extend their tentacles during the dark hours to consume different kinds of planktonic organisms.

Conservation Status

Although it is not one of the primary reef-builders, like the stony branching corals that construct networks used as shelter by reef organisms, they are important for creating reef diversity.

The IUCN Red List of Threatened Species assessed the artichoke coral (Scolymia cubensis) back in 2021 and recorded them as being "Critically Endangered" (CR) with a "Decreasing" population trend.

Some of the most pressing concerns that threaten their long term survival include coral bleaching (habitat decline), underwater waste pollution, overharvesting for the aquarium trade, and excessive sedimentation (often caused by uncontrolled erosion).


Bubble Coral (Plerogyra sinuosa)

Bubble coral (scientific name Plerogyra sinuosa) is a fascinating gelatinous organism found in some tropical marine environments.

This section contains fun facts and information about bubble corals and why this bubbly hard coral species is essential for some fish families and other reef-dwelling creatures.


Cauliflower Coral (Pocillopora meandrina)


Elephant Skin Coral (Pachyseris rugosa)


Elkhorn Coral (Acropora palmata)

Several global factors (e.g. climate change) threaten the survival of most corals located in shallow tropical reefs and lagoons because it interrupts the symbiotic relationship they have with algae.

This section contains detailed facts and interesting information about elkhorn coral, and the significance of healthy "bush-like" coral species for fish families and other reef organisms.


Fire Corals (Millepora)


Fleshy Disk Coral (Scolymia lacera)


Golfball Coral


Great Star Coral (Montastraea cavernosa)


Grooved Brain Coral(Diploria labyrinthiformis)


Honeycomb Coral (Diploastrea heliopora)


Lattice Table Coral


Leaf Plate Montipora


Leptoseris Corals


Lettuce Coral (Agaricia agaricites)


Lobe Coral (Porites lobata)


Mountainous Star Coral


Orange Cup Coral (Tubastraea coccinea)


Pillar Coral


Porites Lutea

Porites coral, of the genus scleractinia (meaning stony coral), is also known as finger coral (scientific name Porites compressa), boulder coral, and sometimes hump coral.

This finger-like characterisation and morphology is typical of the Porites species that create colonial rings of corals (microatoll formations) and large sturdy habitats for Spirobranchus giganteus.


Serpent Coral (Pachyseris speciosa)

The elephant skin appearance and the pale brown colouration of serpent coral (Pachyseris speciosa) helps to distinguish it from other similar corallites found in tropical reef environments.


Staghorn Coral (Acropora cervicornis)

Several global factors (e.g. climate change) threaten the survival of most corals located in shallow tropical reefs and lagoons because it interrupts the symbiotic relationship they have with algae.

This segment contains detailed facts and information about staghorn coral, and the significance of healthy "bush-like" coral species for fish families and other reef organisms.


Starry Cup Coral (Acanthastrea echinata)


Sun Coral (Tubastraea)

Unlike most corals, and despite the sun-like appearance of the polyps, Tubastraea are non-photosynthetic - which means they can survive with extremely low levels of sunlight.

Check out these fun facts and information about sun corals (Tubastraea), including where they thrive best, what they eat, and how these cup-shaped polyps reproduce.


Tabletop Corals (Acropora hyancinthus)


Yellow Pencil Coral

Types of Soft Coral Formations

Black Sea Rod (Plexaura homomalla)


Cabbage Leather Coral (Sinularia brassica)


Carnation Corals


Dead Man's Fingers (Alcyonium digitatum)

There is a colonial species of soft coral with branching, finger-like encrustations (lobes) that resemble the fingers of an upturned human hand.

This segment contains facts about dead man's fingers coral, and why this epifaunal sea creature thrives around the United Kingdom coastlines.


Fan Corals (Alcyonacea)


Finger Leather Coral (Sinularia corals)


Giant Black Coral Whip (Cirrhipathes)


Mushroom Corals (Fungiidae)


Organ Pipe Coral


Purple Soft Coral (Alcyonium fauri)


Sarcophyton Ehrenbergi


Sea Fingers


Sea Pen (Pennatulacea)

Even though they are often mistaken for plants, this species of colonial invertebrates get their common names from the resemblance to old-fashioned feather quill pens (once used in writing).

Check out these interesting facts about sea pen (Pennatulacea) soft coral, such as where they live, what they eat, and the reproductive strategies of soft coral that looks like a writing quill.


Toadstool Leather Coral (Genus Sarcophyton)


Wire Coral

Frequently Asked Questions about Coral

All corals are (or were) living organisms. They are not simply mineral rock! Put another way, a coral reef is a colonial collection of marine organisms that are either alive or dead.

What are Corals Made Of?

Most of the six thousand different coral species thrive best in warm, shallow, coastal waters. But, you can also find corals deep down in the darkness of open oceans.

In fact, corals are marine invertebrate animals that form huge underwater structures. Coral reefs provide sheltered habitats and food sources for 25% of fishes worldwide.

What are Porites?

A porite has an exceptionally sluggish growth rate. In fact, some porites coral species (e.g. Porites lutea) grow less than one (1) centimetre per year.

But, the tall giants of seven or eight metres high rank among the oldest and most established of all earth life forms.

What are Reef Producing Coral Called?

Understanding how hermatypic corals (tiny polyp structures) produce fabulous coral reef gardens is often misunderstood and underestimated.

The two main coral types are the reef-builders (hermatypic coral) and the non-reef-builders (ahermatypic coral) which, even though they're found worldwide, do not produce reefs.

What Do Artificial Reefs Do?

They are becoming popular in many diving destinations around the world and the reasons for creating an artificial reef vary in different oceans and environments.

What Causes Coral Bleaching?

Simply put, coral reef bleaching happens as a result of factors that cause tissue discolouration. It can turn the normal vibrant colours and pale brown into white.

Even though the inexperienced diver may admire the apparent snow-like environment, it is a sign that the coral is distressed.

Why Do Corals Get Disease?

You don't need to be a scuba diver to learn that healthy coral is less common nowadays. Find out how the different types of coral diseases are caused by various pathogens, fungi, and bacteria.

What are Coral Reef Bommies?

Originating from the Australian term "bombora", coral bommies are usually seen as separate submerged structures that have developed some distance away from sprawling reef systems.

In marine ecosystems, coral reef bommies refers to isolated rocky outcrops or small pinnacles that rise up from the ocean floor.

10 Steps to Save Coral Reefs

Join the actions of concerned individuals by discovering some of the most pressing problems facing these vulnerable environments. Then, you can also help to protect and conserve them.

The Project AWARE course is informative and interesting. It's also a great way to make a difference, and you don't even need to get scuba qualified.

Here's the deal:

You can make a positive impact against global Earth climate change, ocean acidification, coral bleaching, and other world threats to our oceans by helping to preserve coral formations.

Collectively, following these simple steps below "will" make a difference. The daily actions of everyone are effective!

  1. Educating the public of the seriousness is imperative. People need to learn, read about, and take action against marine pollution. The more information you learn, the better the actions, with more success directly impacting conservation. Saving the Earth is everyone's responsibility.
  2. Not everyone lives near coral reef formations. However, if you plan a vacation accordingly, it's a great opportunity to visit a local marine park. Volunteer organisations would benefit from your inclusion of their surveys and clean-ups.
  3. Take steps to lower your carbon footprint. Planting trees helps to reduce run-off and reverse global warming. Walking or using public transport helps to reduce pollution because driving cars, and many industries, emit fossil fuels that also influence the 7 factors that cause coral bleaching.
  4. Coral reefs are precious. Although they portray a rocky appearance, corals are delicate animals. If you go diving or snorkeling, do it responsibly, using appropriate anchoring techniques and do not touch the reef.
  5. Plan to eat sustainable seafood. Seafood Watch produces a pocket guide that highlights seriously overfished species such as bluefin tuna, blue marlin, Atlantic cod, salmon, sea bass, and others.
  6. Fertiliser products eventually run into the seas, polluting the water, and harming coral reefs and marine animals. Try to use organic fertilisers that are eco-friendly, to reduce the impact on our water systems.
  7. Using water conservatively creates less waste-water. Dispose trash and litter properly. When garbage ends up in the sea, it is extremely harmful for marine life animals.
  8. You can contact your local governmental representatives and petition them to increase their activities against marine pollution. Peaceful demonstrations are increasingly changing the way that governments act.
  9. It makes sense to support "eco and reef-friendly" businesses and organisations. So-called "Green" scuba diving business operatives actively engage in conservation activities and sustainable practices. You can learn more about these establishments from the National Green Pages.
  10. Scuba divers and water enthusiasts are ambassadors for the underwater world. Spread the message that every coral reef formation needs our help.

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