The corals of the Andaman Sea

Colourful fishes have always been a favorite to tropical sea divers but have you taken a closer look at the gorgeous coral species that inhabit the Andaman Sea?  
Do you know what corals are? How coral grows to form the coral reefs (Planet earth largest living structures)  and why they are so important for our planet?
Contrary to common beliefs, corals are animals, not plants and surely neither rocks!
What you see above is actually a group of animal living under the same roof... developing over time like any living thing.

---

How do coral reefs form?

1. Coral reefs release eggs and spermatozoa (gametes).
2. After fertilisation (meeting of a male and female gamete), a ciliated larva called planula is formed.
3. The larva will attach itself to a place favourable to its development and form a flat disc.
4. A polyp will form and then bud (each polyp secretes a hard exoskeleton, made up of calcium carbonate, as well as an internal limestone skeleton that remains in place even after the death of the animal), to give what we know today like coral. 

​
The successive budding of the polyps makes it possible to continuously enlarge the coral colony which, over time, forms the reefs.

​The reefs are therefore made up of colonies of polyp corals held together by calcium carbonates. Note that polyps alone could not live and reproduce without their symbiotic relationship with zooxanthellae algae. While the algae provides the animal with the necessary nutrients, the polyp releases carbon dioxide which allows the algae to develop and also to carry out photosynthesis which will give colour to corals in particular.

Coral reef’s life cycle - coralworldvi.com

There are hundreds of species of corals! Most live in tropical seas with optimal conditions for their development: lots of light and a temperature between 25 and 30 ° C.

But then, how to differentiate coral species?

can you spot the stone fish on this nice coral reef?

The magnificent colours of the corals that we, divers, are lucky enough to admire, their shape or even their size allow them to be distinguished in particular.

Red, brown, yellow, green, blue, purple or even fluorescent ... the colour combinations of corals are infinite! Colours can often help divers distinguish one coral from another, but their shape is a better tell tail.

There are two main types of corals: Hard coral and Soft Coral​

Hard coral species of the Andaman Sea

Hard coral are made of a rigid calcium carbonate (polyps' exoskeleton made out of limestone) and appear very much like rocks. When a polyp dies, their skeleton remains and new polyps grown on top of the last ones enlarging the coral one life at a time. Hence hard coral grows very slowly.
There are several categories of hard corals encountered in the Andaman Sea, each of these with many sub-categories and species.

Branching corals

Branching corals

• Branching corals are made up of a multitude of branches often used as nurseries to keep the baby fish out of harmway.

Elkhorn & Staghorn Coral:

• Elkhorn / Stahorn Corals resemble branched elk horns (Elkhorn corals) or deer (staghorn corals) which tend to protrude vertically with a large number of side branches.

Elkhorn / Stahorn Corals

Encrusting corals

Encrusting coral

Encrusting corals form a crust on a substrate by spreading over their surface and thus create a thin coloured layer.
This is the perfect place for christmas tree worms and encrusting shells to settle.

Foliose corals:

Growing outward and only attached to the reef from their center "trunk", Foliose corals are often compared to heads of lettuce.

Massive corals

With a very slow growth (from 0.5 to 4.5 cm / year), these round-shaped corals bummies constitute "the pillars" of most reefs, in the Andaman Sea and beyond! They can reach massive sizes like the multi million years bummies depicted bellow from the Burma Banks.

Massive corals

platygyr brain coral mussidae

Mushroom Corals

Mushroom corals are fairly solitary corals. They can be found on the sand and do not attach to other corals. Made up of a single polyp, mushroom coral can reach 25 cm in diameter.

Mushroom corals

Table corals

Table corals:

Table corals are easily recognisable thanks to their horizontal structure which gives them great stability and perfect hiding places for other animals of the Andaman Sea and a particularily appreciated nursery for butterfly fishes.

Bubble corals

Often mistaken for eggs, pollyps ressembles bubbles during the days which deflates at night to let the polyps feed. Despite their soft appearance, bubble corals have a "stony" structure and are hence classified as hard corals.

Bubble Coral, or Plerogyra sinuosa

Orange Cup coral

Another nocturnal coral with fleshy appearance, the orange cup coral is indeed a hard coral. It is classified as ahermatypic, because it doesn't contribute to building the reef.
In fact it is a pretty invasive specie which spread quickly favouring on rocky walls and chasing away sponges and hydroids.
The polyps retract during the day and "blooms" at night covering the wall with beautiful yellow
"flowers". 
Next time you see them, make sure to look closely for the pretty yellow snails that feed from them. 

Sun corals or orange cup coral

Cup corals are one of the most colourful hard coral specie on the Andaman Sea.

Soft Corals species in the Andaman Sea

Soft corals are easiest identified from hard coral because they do not have a hard skeleton. They also have 8 arms per polyp. 

Carnation corals

Carnation corals are soft corals that love curants, their amazing vibrant colours make them some of the favorites for underwater photographers.

Richelieu Rock is famous for the purple coloured carnation coral that covers the best dive site in Thailand.

red whip coral in the front, bushy Carnation soft Coral behind and giant seafan in orange

Seafans

The Andaman Sea was gifted with several types of seafans, tall web-like fan structures in various colours. The most impressive is probably the Giant seafans (Anella mollis) which can reach 2 meters in diameter!

Giant seafan in the Andaman Sea

Why are corals important?

Not only are coral stunningly beautiful and giving the Andaman Sea its colours but they are so much more important than for background imagery! 
1- coral feed small critters and fish that feed the bigger ones, no coral= no more fish!
2- 500 million people make a living from coral reefs: from fisheries to tourism
3- coral reefs can reduce waves by 95% and could save the coastline from the damaging effects of tsunamis and storms
4- Coral reefs are also the lung of our planet! Generating half of our planet's oxygen and absorbing about a third of the carbon dioxide generated from fossil fuels usage.

Wonderful corals of the Andaman Sea

Coral reefs are in danger! Help us make them last longer!

Coral reefs have already been reduced by more than 50% and our generation might be the last one to witness one of our planet's greatest treasure before it disappear.

OUR ACTIONS now will determine if our children will see it too.
​
The Smiling Seahorse is commited to ocean preservation, when you go diving, make sure to chose and eco friendly operator to reduce your ecological footprint.

coral bleaching due to ocean warming is one of the many treats to coral reefs

The Smiling Seahorse's promises

• to abides by Green fins  principles
• to encourage environmentally responsible diving practices
• to reduce/ reuse/ recycle as much as we can, especially plastics
• to offer reef friendly amenities: such as our refillable organic, reef-safe Soap, Shampoo and hair conditioner.
• to ask all our employees to help in ocean conservation efforts
• ​To support marine science research and clean up projects