Monday, December 31, 2012

Nature Interpretation for Beginners

I started doing nature guiding in 2005, and I could still remember that at that time, training for guides was quite location-specific - we discussed the standard operation procedures for the location, share about the background of the location, and learn about the flora and fauna found there. Although we also discussed about some of the guiding techniques, it was more of the experienced guides highlighting what they thought were important. While the techniques were useful, they were essentially what the guides could think of at that point in time, and hence we had to learn a lot of things on our own through trial-and-error. At that time, I have not even heard what nature interpretation is.

I started assisting with the training of nature guides in late 2006, and become a main trainer in 2007. The training content I used were consolidated from the experiences I gained as an active nature guide and from other experienced guides, as I tried to design a proper structure for training guides, and adopt a more systematic approach for the whole process.

It was only in recent years that I heard about nature interpretation, and started reading up about it. It felt weird to think that to some extend I had been trying to reinvent the wheel last time, though what I had come up with previously was more specific to Singapore, or at least to a particular nature spot. After finding out more about the experts' views on nature interpretation, I also realised then that there are definitely several good practices that are quite universal for most nature walks. It will be useful to train new guides with these universal good practices, and at the same time, include some practices that will be more relevant to the local scene.

So in this blog entry, I will attempt to share the things I have learned, the experiences I have gained, and what I personally feel is important with regards to nature interpretation.

A) What is Nature Interpretation?

Personally, I feel it is a communication process to facilitate the understanding of the various biotic and abiotic components of our natural environment and the relationships between them.

"Facilitate" is a key word here, as I feel it is not just about communicating what you know with the audience, but create a platform to allow the communication to take place. In other words, while in most cases the information may come from the nature guide, it is also possible that the information may come from a member of the audience. Hence, the guide should ensure that there is proper interaction and not a one way communication, and must also be humble enough to accept that sometimes the audience may know more about a particular topic than the guide.

B) Role of a Nature Interpreter/Guide

The interpreter will have to facilitate the communication of ideas, feelings and values so as to provoke audiences to do their own thinking and develop their own understanding of nature and appreciate the importance of nature, hence be inspired to play a part in nature conservation.

He/she also have to be a role model for the participants. Actions speak louder than words, and hence if the guide shows that he/she really care about nature, the audience will be more positively influence. For example, the guide should not make unnecessary noises and end up disturbing the wildlife, and also, should not feed animals or rescue prey from predators, but let nature takes its course.

It is also important that he/she ensures the safety and comfort of the audience, and that the entire programme is smoothly run.

C) Guiding is MAD!

A nature interpreter will need to manage the Message, the Audience, and the Delivery of the message during a nature walk.

D) Crafting the Message

The message is what the guide will be saying to the participants. A beginner nature interpreter should always write a script for the messages he/she will be conveying for a walk, and the script should be written as if he/she is talking to the participants, i.e. not in point form. Writing a script will give the interpreter an idea of how exactly he/she should do the commentary, and serves as a backup if the beginner guide gets stage fright. Experienced guides can also look at the script and give tips on how it can be improved.

The message should strive to be EROTIC - Entertaining, Relevant, Organised, Themed, Inspiring and Conversational.

Entertaining - When the participants find the nature walk enjoyable, there will be a higher chance that they will like the nature spot better, remember what they have learned during the walk, and more motivated to want protect the nature spot. As such, it is usually a good idea to include some jokes and topics most people are interested with (e.g. food and sex) to ensure that the participants are not bored. However, while jokes are to be included, the interpreter should avoid putting an organism in a bad light, e.g. saying it is disgusting or evil etc, or the participants may subconsciously develop negative emotions for nature.

Relevant - Avoid confusing the participants by talking about things that are not relevant to the topic. For example, I have witnessed a guide showing the participants a living snail, and ended up spending most of the time talking about hermit crabs occupying dead snails' shells. There was another occasion when I overheard a guide talking about vampire bats when the subject was a fruit bat. Unless the participants ask (which the guide may choose to give a short reply), the guide should focus on what is in front of them. And obviously, the script prepared by the guide should be regarding the flora and fauna that can usually be found along the chosen nature trail. While explaining difficult concepts, it is also useful to use analogies relevant to the participants, i.e. something that they are familiar with, so that they can relate better to them.

Organised - A message should be coherent, or else the participants will have a hard time trying to understand what the guide has said. Start the story with a statement that will draw the participants' attention to the organism. E.g. "We are really lucky to see this today! This is a XXX" or "Does anybody know what this is?" After that, elaborate 2 or 3 interesting topics regarding the subject matter, i.e. the plant, animal etc. The guide should avoid trying to show off how much he/she knows, or the participants may be put off. Ensure that the message flows smoothly, and a complete picture of every topic is presented. The message should have a proper closure, so that the participants got the signal that it has ended and they can move on.

Themed - The theme refers to the core idea(s) for the commentaries, and it is very important because it determines what the guide wants the participants to know, what he/she hope they will feel, and how he/she hope they will behave during and after the activity. A nature walk may have more than one theme. For example, if the theme is biodiversity, the guide will try to introduce more flora and fauna with shorter commentaries, but if the theme is conservation then the guide will spend more time on the conservation status of the flora and fauna, and how are they threatened, and what can be done to conserve them.

Inspiring - Singapore has very few nature spots left, and hence as far as possible we hope to inspire the participants to be involved with conservation. The guide can ask thought-provoking questions, e.g. what will happen if a particular plant/animal goes extinct? Will we lose a potential cure for some diseases? The guide should lead by example to care for the environment (actions speak louder than words!), but should never promote his/her personal achievements as some participants may be put off. The guide can also give suggestions on the little things everyone can do to contribute to conservation.

Conversational - The guide should avoid talking like he/she is giving a documentary commentary, but more like talking with a friend. The message script should hence also be written as such, and not in the form of an essay or in point form. If the commentaries are made like a speech, the personal touch will be absent, and it will be harder to get the participants to trust the guide and feel for the things that are discussed. Similarly, the guide should not be talking down in a superior tone (i.e. I know more than you). A few simple questions should be added to encourage the participants to interact and express their views. Questions requiring "Yes" or "No" answers make it easier for participants to answer. Questions can also be used to draw the participants' attention, and the response can be an action rather than a verbal response. E.g. "Can you see the tiny hair on XXX's back?"

E) Managing the Audience

The audience refers to the participants, and it is important to manage the audience well to ensure that a nature walk is a success. And really, managing the audience is a SCAM - the guide needs to ensure their Safety and Comfort, then try to get their Attention, and watch out for Misbehaviours.

Safety - It is always important to conduct a safety briefing and ensure that the audience follows instructions. As a usual rule, the participants should not touch anything along the trail without permission, as some of the things may be dangerous, e.g. poisonous plant, venomous animals etc. It is also important to remind them not to wander off the trail, as they may be causing damage to the nature area, and also there could be dangers (hidden holes, snakes etc). Singapore is usually quite hot, and hence it is good to remind them to drink water. Also, the guide should keep a look out for anyone not feeling well. The guide should also take note of bad weathers, and must be familiar with the evacuation procedures in case any emergencies.

Comfort - After ensuring the safety of the audience, the guide must ensure that their comfort as far as being realistic, since they my get very restless if they feel uncomfortable. For example, the guide should be the one facing the sun, not the participants. If the trail has biting insects, the audience should be reminded to spray insect repellent before they enter the trail. It is also important not to force participants to touch or taste things if they don’t want to. Sometimes, there could be delays in the trip, and hence the guide should communicate the reasons for the delay with the audience, and keep them occupied.

Attention - When the audience feel safe and comfortable, it will be easier to get their attention. The guide should take note of environmental noises (airplane, factory etc), and move away or wait for the sound to subside before continuing with the commentary. The message should also be tailored to the audience to get their attention. For example, the guide can also use analogies relevant to the audience's experience to allow them to relate to the subject matter better. It is also important not to use scientific or difficult words for a public group or they will not be able to understand the commentary. Also, the guide can choose topics that are more relevant to the type of audience, e.g. joke about reproduction adaptations with only adults; use examples from kids programmes when dealing with children; use local examples such as what can be eaten or used for local groups, or compare with foreign customs for foreign groups etc. It is hence important to interact with the audience to know what they want and adjust accordingly. Depending on the interest level, the guide may adjust the length of the message.

Misbehaviours - It is important to manage misbehaving participants, and they can affect the other participants. Examples of misbehaviours include: visitors doing anything dangerous; asking irrelevant questions repeatedly; asking too many questions and delay the trip; and wandering off the trail etc. to manage such participants, the guide can: remind them nicely to behave themselves; inform them time is running out, and you will answer the questions at the end one-to-one; or in cases which the participant refuses to improve his/her behaviour, inform the organiser, who can remove him/her from the group so that the walk can proceed smoothly and the mood of the other participants will not be spoilt.

F) Delivering the Message

When a guide delivers his/her commentary, he/she is actually communicating using both verbal communication and nonverbal communication.

Verbal Communication - This is communication using words i.e. the spoken message, which was what we have covered under the section Crafting the Message. But it is important to note that the scripted message is just a reference, and as mentioned under the section Managing the Audience, the actual verbal message delivered should be adjusted to match the type of audience.

Nonverbal Communication - This refers to communication without using words, which includes the use of the various Senses, Nonverbal aspects of talking, Attire, and Body language, otherwise shortened as SNAB.
  • Senses - The guide should try to use all the five senses to communicate with the audience. For example, he/she can listen out for bird or insect calls, look out for movements or camouflaging animals, smell the herbs and spices, touch and feel the texture of leaves, and taste edible fruits and herbs. All these experiences will make a nature walk more unforgettable for the audience!
  • Nonverbal aspects of talking - These include the pitch, clarity, intonation, volume, speaking style. It will be very boring if the guide use a monotonous voice all the time. When talking about something exciting, the guide can raise his/her pitch, speed of talking and volume, and when talking about something creepy, he/she can lower his/her pitch and volume. The varying way of making the commentary can make the experience a lot richer.
  • Attire - This refers to what the guide is wearing. To appear professional and enthusiastic about his/her role as a nature interpreter, slippers and other sloppy attire should be avoided. First impression does count, and the audience will tend to trust a guide who is properly attired more.
  • Body language - This includes facial expressions, eye contact, body posture, intentional and unintentional gestures, and personal space. It is good to keep eye contact with the audience, so as to grab their attention. Dramatic facial expressions will help to make the commentary more interesting. The guide should avoid slouching, as he/she will appear disinterested and lazy. It is good to have some gestures, but avoid having too many hand movements as it may confuse or distract the audience. It is always good to give the audience some personal space - they will move closer to the guide when they are more comfortable with him/her.

G) Conclusion

The above are just my 2 cents' worth of what I feel is important while doing nature interpretation. I will think that most experienced nature guides will have their own ideas about what makes a good nature guide, and hence I will assume that there will be guides who disagree with the above techniques. But I guess this should still serve as a good reference for beginner guides! All roads lead to Rome, and as long as the audience has a positive experience and their understanding and appreciation of nature are improved after the guided walk, I would think the nature interpreter has done a good job! :)

Sunday, December 30, 2012

Soft Corals (Phylum Cnidaria: Order Alcyonacea) of Singapore

Soft corals (phylum Cnidaria, class Anthozoa, subclass Octocorallia, order Alcyonacea) are radially symmetrical animals connected to each other by a fleshy tissue (instead of a calcareous skeleton found in hard corals). Like other cnidarians, they possess explosive, harpoon-like cells called cnidocytes. Each cnidocyte contains a secretory organelle (cnidae), which can be a nematocyst that discharges a harpoon-like stinger carrying toxins, a ptychocyst that discharges sticky substances, or a spirocyst that discharges lasso-like threads. Hence while cnidocytes are often called "stinging cells", they do perform other functions apart from stinging. Many soft corals can also secrete chemicals to deter other organisms from competing for space with them.

Xenia sp.
The coral animal, or polyp, has a simple body comprising a stomach (coelenteron) and a mouth surrounded by tentacles (where most of the cnidocytes are located), appearing like a little flower. The tentacles occur in multiples of eight, and hence they are in the subclass Octocorallia. It does not have an anus, and thus the mouth performs both functions of ingesting food and removing waste.

Soft coral colonies
Colonies of soft corals may cover extensive areas of the coral reef. The rigidity of the colonies are usually maintained by a hydrostatic pressure system, which is basically water pumped through the colony. They also often have tiny spiky particles called sclerites to provide support for the tissues.

Many soft corals harbour the unicellular algae, zooxanthellae, inside their tissues, which give them a brownish colour. The zooxanthellae produce food through photosynthesis and share the food with the host corals, and in return get shelter and nutrients (waste products of the corals). Soft corals also actively feed on plankton with their tentacles.

Soft coral bleaching
Sometimes, the corals may expel their zooxanthellae or the latter may leave the coral due to environmental stress, resulting in a phenomenon known as coral bleaching. Without the zooxanthellae giving the corals their base colour, the corals turn white and appear bleached. One of the main causes of coral bleaching is the rise in water temperatures. If the situation does not improve and the soft corals cannot recruit new zooxanthellae to replace the lost ones, they may die.

Briareum spawning
Soft corals can reproduce sexually or asexually. In sexual reproduction, some species broadcast their eggs and sperm into the sea in mass synchronous spawning, while others fertilise their eggs internally. The fertilised egg develops into a free-swimming larva, which will cement itself onto a suitable hard substrate, builds a corallite, secretes a hard skeleton, and eventually clones itself to form a colony. In asexual reproduction, the polyp can split into two (intratenacular budding), or a new clone may grow from the base of an existing polyp (extratentacular budding).

Autozooids and siphonozooids
Many soft corals have two types of polyps: autozooids, the feeding polyps, which usually have 8 feather-like tentacles (inset; and contracted stalk-like structures in main picture); and siphonozooids, the water intake polyps, which are usually greatly reduced in size, and their tentacles are rudimentary (flower-like structures carpeting the areas around the stalk-like autozooids in main picture).

Much of my knowledge on soft coral identification was gained from marine biologist Ong Joo Yong (thanks a million, Joo Yong!). My knowledge is still quite limited though, and hence I can only try to identify many of them to their genera. So if you find any mistakes below, do let me know!


Family Alcyoniidae

Alcyoniid soft corals usually have tiny polyps housed in a shared leathery tissue, and hence they are comonly called leathery soft corals. Depending on the genus, they may either have both autozooids (with long trunks and eight tiny branched tentacles) and siphonozooids (which remain below the leathery surface, appearing as tiny holes or mounds), or only autozooids. The autozooids usually only emerge when the colony is fully submerged. Most species harbour zooxanthellae, and the colonies are mostly massive, though some may appear encrusting.

Sarcophyton spp.
Sarcophyton spp. are usually somewhat mushroom-shaped, and hence they are sometimes called toadstool leather corals. The mushroom-shaped colony comprises a disc-shaped structure called the polyparium (which carries the polyps) sitting on a stem-like structure. The polyparium usually have open folds on its margin. The polyps are dimorphic, meaning there are both autozooids and siphonozooids. When submerged, the long, tubular autozooids will emerge, while the small siphonozooids remain as small bumps on the leathery surface. They harbour zooxanthellae.

Lobophytum spp.
Lobophytum spp., commonly called the lobed leather corals, also have a disc-like polyparium sitting on a stem, but the polyparium comes with vertical lobes, ridges or finger-like structures. It also has both types of polyps, and the autozooids are often white in colour. These soft corals harbour zooxanthellae as well.

Cladiella spp.
Cladiella spp., sometimes called blushing finger leather corals, form comparatively small colonies as they usually divide into several separate colonies on reaching certain sizes. The colonies often have a small stalk, and the polyparium is covered with numerous finger-like or knob-like lobes. They only have autozooids, which usually do not retract completely into the fleshy tissue, which has lots of sclerites. A drastic colour change is observed when the brown-coloured polyps retract to reveal the white-colour fleshy tissue, giving it a whitish appearance marked with small dark spots (the partially retracted polyps). ) They harbour zooxanthellae in their tissue.

Sinularia spp.
Sinularia spp., sometimes called dead men's fingers, usually form massive colonies with numerous finger-like projections on the polyparium. They only have autozooids, and the layer of tiny polyps give the colony a furry appearance. The lack of siphonozooids gives the colony a smoother texture compared with most other leather corals. They harbour zooxanthellae as well.

Family Nephtheidae

Nephtheid soft corals usually appear tree-like corals with a main stem and many branches. They have long, canal-like chambers which can be filled with water, allowing the colony to stay firm and erect to bigger sizes for stability. When disturbed, they are able to release water from the chambers in their stem quickly so as to shrink to smaller sizes.

Litophyton spp. and Nephthea spp.
Litophyton spp. and Nephthea spp. (also spelled as Nephthya sometimes), are bush- or tree-like with their branched polyparium. The polyps are arranged in clumps on the terminal branches, and while they can close (or contract), they cannot retract into the branches. On the lower sides of the polyps, supporting bundles of pointed spindle-shaped sclerites can be seen in Nephthea, but not Litophyton. Recent phylogenetic studies, however, have suggested that Nephthea soft corals should be synonymised with the Litophyton genus. Pending this to be more widely accepted, it is probably acceptable to say all the above are Litophyton spp. Zooxanthellae are present in both genera.

Stereonephthya spp.
Stereonephthya spp. are also bush- to tree-like. The polyps occur in bundles directly on the stem and the few secondary branches with supporting bundles. They usually feel very spiky and firm when touched, and while they can contract, they do not retract completely into the branch. On the stem surface, numerous sclerites of a contrasting colour can be seen. They do not host zooxanthellae. Recent phylogenetic studies, however, have shown that some Stereonephthya species should be Nephthea species instead.

Dendronephthya spp.
Dendronephthya spp. also have no zooxanthellae. The colonies usually appear tree or bush-like, and the polyps occur in bundles (no catkins). Each polyp has a supporting bundle of sclerites, and on the stem surface, sclerites of a contrasting colour can be seen. Recent studies suggest that they should be a junior synonym of Litophyton as well. are branched, on surface sclerites can be seen, which are contrastingly coloured.

Family Xeniidae

Xeniid corals usually occur as small groups between populations of hard corals. They mostly have long polyps extending from a short and stem-like common body mass, though in some cases, this body mass is reduced to a thin basal crust. The digestive tracts of the polyps are usually much reduced, and hence they mostly rely on the zooxanthellae in their tissue to provide most of their nutritional requirements. It is suggested that they can absorb organic compounds from the surrounding water as well.

Heteroxenia spp.
Heteroxenia spp. have both types of polyps - the autozooids (the long polyps) and siphonozooids (the smaller flower-like polyps carpeting the surface). The juveniles, however, lack siphonozooids, and may be difficult to identify. The colonies are usually upright, with long, flower-like polyps. The polyps can contract, but do not retract completely into the stalk. As mentioned earlier, they rely mostly on the zooxanthellae for nutrition.

Xenia spp.
Xenia spp. also form upright colonies with long, flower-like polyps. They only have autozooids, and this can be easily seen when the polyps contract - they lack the carpeting siphonozooids. Like the previous genus, the polyps cannot retract into the stalk. Interestingly, the feather-like tentacles are often seen pulsating, possibly to improve the exchange of oxygenated water. The specimens I have seen in local waters also tend to have a brighter colour compared to those from the previous genus. They are highly dependent on the zooxanthellae in their tissues.

Sansibia spp.
Sansibia spp. have polyps arising from soft spreading membranes or ribbon-like horizontal branches (stolons). They only have autozooids, and the polyps can contract but do not retract into the membranes or stolons. Hence, they often appear as blue or green patches on the substrate when they are exposed during low tide. Like other xeniids, they have zooxanthellae in their tissues.


These three suborders were previously placed under the order Gorgonacea, which has been synonymised with the order Alcyonacea.

Family Briareidae

This family only has one genus - Briareum. The only other genus previously placed under this family have been synonymised.

Briareum sp.
Briareum spp. form encrusting colonies with short cylindrical tubes housing the autozooids - they do not have siphonozooids. The colonies have a soft and furry carpet-like appearance when the polyps are extended. When the polyps retract into the cylindrical tubes, the bottom crust (coenenchyme) is revealed. Sometimes, they can cover living structures such as sea fans or hard corals, and assume their shape. They harbour zooxanthellae in their tissues.

Family Ellisellidae

Ellisellid soft corals may form whip-like, bushy, or fan-like colonies with a calcified solid axis exhibiting a radial pattern in cross section.

Junceella spp.
Junceella spp. occur in unbranched, whip-like colonies, and hence they are commonly called sea whips. It has no zooxanthellae.

Ctenocella pectinata
Ctenocella pectinata forms colonies branching in one plane, appearing comb-like or lyre-like. It has no zooxanthellae as well.

Dichotella sp.
Dichotella spp. form colonies which are dichotomously branched. They may appear bushy or fan-like, but generally the branches are whip-like. They lack zooxanthellae as well.

Other Sea Fans

Sea Fans
Many other species of gorgonians can be seen in local waters, but unfortunately my knowledge of sea fan identification is too limited to identify them, and I do not have friends who are familiar enough with this group to provide tips on the identification. Hopefully I will eventually get to know someone who can help me with this! :)


Family Clavulariidae

Clavulariid soft corals do not form colonies with a thick common tissue. Instead, they either form encrusting colonies with polyps joined at the base by root-like creepers (stolons), or bushy colonies with branches connected the polyps.

Carijoa spp.
Carijoa spp. form small bush-like colonies, with long primary polyps producing many secondary polyps by lateral budding. They usually occur at shady areas, such as under jetties, in caves or under overhanging coral colonies. Sometimes, the colonies may be overgrown with encrusting sponges, such as the ones in the insets which are covered with orange and light brown sponges. They have light coloured polyps, and lack zooxanthellae.

  • Chou, L. M. 1998. A Guide to the Coral Reef Life of Singapore. Singapore Science Centre. 128 pp.
  • Erhardt, H. and D. Knop. 2005. Corals: Indo-Pacific Field Guide. IKAN-Unterwasserachiv, Frankfurt. 305 pp. 
  • ETI BioInformatics. 2012. Marine species identification portal. Retrieved Dec 29, 2012, from
  • Goh, N. K. C. and L. M. Chou. 1996. An annotated checklist of the gorgonians (Anthozoa: Octocorallia) of Singapore, with a discussion of gorgonian diversity in the Indo-West Pacific. The Raffles Bulletin of Zoology 44 (2): 435-459
  • Ofwegen, L.P. van, and D.S.J. Groenenberg. 2007. A centuries old problem in nephtheid taxonomy approached using DNA data (Coelenterata: Alcyonacea). Contributions to Zoology, 76(3): 153-178.
  • Ruppert, E.E. and R.D. Barnes. 1991. Invertebrate Zoology (International Edition). Saunders College Publishing. U.S.A. 1056 pp.
  • World Register of Marine Species. 2012. Retrieved Oct 3, 2012, from

Tuesday, December 25, 2012

Hard Corals (Phylum Cnidaria: Order Scleractinia) of Singapore

Hard corals (phylum Cnidaria, class Anthozoa, subclass Hexacorallia, order Scleractinia) are radially symmetrical animals with hard calcareous skeletons. Like other cnidarians, they possess explosive, harpoon-like cells called cnidocytes. Each cnidocyte contains a secretory organelle (cnidae), which can be a nematocyst that discharges a harpoon-like stinger carrying toxins, a ptychocyst that discharges sticky substances, or a spirocyst that discharges lasso-like threads. Hence while cnidocytes are often called "stinging cells", they do perform other functions apart from stinging.

Coral polyps
The coral animal, or polyp, has a simple body comprising a stomach (coelenteron) and a mouth surrounded by tentacles (where most of the cnidocytes are located), appearing like a little flower. The tentacles occur in multiples of six, and hence they are in the subclass Hexacorallia. It does not have an anus, and hence the mouth performs both functions of ingesting food and removing waste. The polyp resides in a calcareous structure called a corallite, and most species can clone themselves into huge colonies stretching many metres, comprising thousands of corallites side-by-side.

Coral Reef
The many colonies of hard corals occuring side-by-side form a coral reef. Most corals appear brownish, due to the unicellular algae, zooxanthellae, which live inside them. Corals with zooxanthellae are called hermatypic corals, and they have extensive calcareous skeletons which contribute to reef-building. Corals without zooxanthellae are called ahermatypic corals, and they do not contribute to reef-building. The zooxanthellae produce food through photosynthesis and share the food with the host corals, and in return get shelter and nutrients (waste products of the corals). While hard corals also actively feed on plankton with their tentacles, studies have shown that the zooxanthellae sometimes contribute to as much as 95 percent of the corals' nutritional needs.

While most corals appear brownish, there are some that are vividly coloured too. The bright colours mostly come from the corals' own colour pigments, believed to act as a "sun block" to protect the corals from ultraviolet rays. In some cases, the zooxanthellae may be brightly coloured as well.

Coral bleaching
Sometimes, the corals may expel their zooxanthellae or the latter may leave the coral due to environmental stress, resulting in a phenomenon known as coral bleaching. Without the zooxanthellae giving the corals their base colour, the corals turn white and appear bleached. One of the main causes of coral bleaching is the rise in water temperatures. If the situation does not improve and the corals cannot recruit new zooxanthellae to replace the lost ones, they may die.

Intratenacular budding and extratentacular budding
Hard corals can reproduce asexually or sexually. In asexual reproduction, the polyp can split into two (intratenacular budding), or a new clone may grow from the base of an existing polyp (extratentacular budding). Sometimes, part of a coral may be broken off and moved by the currents to another location, where it may attach itself to the substrate and form a new colony if the conditions are right. In sexual reproduction, some species broadcast their eggs and sperm into the sea in mass synchronous spawning, while others fertilise their eggs internally. The fertilised egg develops into a free-swimming larva called a planula, which will cement itself onto a suitable hard substrate, builds a corallite, secretes a hard skeleton, and eventually clones itself to form a colony.

Parts of a corallite
Singapore has more than 260 species of hard corals, and to identify them, it is important to know the parts of a corallite. Much of my knowledge on coral identification was gained from marine biologists Jani Thuaibah and Michelle Lee (thanks both!). My knowledge is certainly nowhere near to theirs, and I can only try to identify many of them to their genera. So if you find any mistakes below, do let me know!

Family Acroporidae

Acroporid corals are usually the dominant corals in pristine reefs, as they tend to be fast growing. However, they are highly dependent on the zooxanthellae for nutrition, and hence prefer clear water which allows more sunlight to reach the sea bed for the algae to photosynthesize better. As such, they are less abundant in Singapore's murky waters, though the diversity remains rich.

Acropora spp.
Acropora spp. often exhibit branching growth forms, and can be identified by a prominent corallite at the tip of each branch. The coral colony as a whole can be bush-like, antler-like or table-like with a flattish top. Some may be encrusting, forming a layer of finger-like structures over rocks or bigger shells. Due to the variety in growth forms, they have been given names such as table coral, staghorn coral, branching coral, and even finger coral.

Montipora spp.
Montipora spp. can be recognised by the papillate, granulated or spiny surface, and the corallite lacks a columella. The colonies may occur in branching, encrusting, or plate-like growth forms. Sometimes, the same colony may exhibit a few forms together, such as being plate-like at the edge of the colony, but have branching structures in the middle. They can appear rather similar to some Porities corals, but the latter has an obvious columella in the middle of the corallite, and does not appear "hollow" like the Montipora corals.

Astreopora spp.
Astreopora spp. often occur in massive boulder-like colonies, though smaller colonies may also occur in encrusting forms. The corallites are conical, and hollow-looking with deep-seated columella, and the coenosteum is granulated. Astreopora corals can be differentiated from the similar-looking Turbinaria corals by the granulated surface and deep-seated columella, as the latter has a smoother surface and a shallow columella.

Family Agariciidae

Agariciid corals generally have small polyps and corallites with indistinct walls. The corallites are situated within depressions or valleys separated by ridges. They generally have a leafy or plate-like appearance.

Pavona spp.
Pavona spp. can be recognised by their corallites, which are separated by prominent septo-costae forming intricate patterns with poorly defined walls. The colony usually exhibits a leafy or plate-like appearance.

Pachyseris spp.
Pachyseris spp. have prominent ridges that are mostly parallel to the edge of the colony. The two species recorded from Singapore are fairly easy to differentiate most of the time: Pachyseris rugosa (main picture) with irregular ridges running in various directions; and Pachyseris speciosa (inset) with concentric ridges.

Family Dendrophylliidae

Dendrophylliid corals generally have rounded and tubular corallites. They can tolerate low light conditions, and hence are commonly seen in local waters. Some species harbour zooxanthellae, while others lack the algae and feed on plankton.

Turbinaria spp.
Turbinaria spp. have big and round (usually tubular) corallites (wider than 0.5cm) with broad and compact columellae. They harbour zooxanthellae, and the colony can have leafy, plate-like, boulder like or columnar growth forms. In some species, the leafy or plate-like structures may twist and overlap each other, giving the colony a turban-like appearance, and hence they are sometimes called turban corals.

Tubastrea spp.
Tubastrea spp. often come in bright colours, which are due to the corals' own colour pigments since they lack zooxanthellae. They have cup-like, circular corallites, and the septa are not fused in adults. The polyps are large and fleshy. The species most commonly seen in Singapore is Tubastraea aurea, which is bright orange in colour. Tubastraea diaphana, which is black in colour, is more often seen in deeper waters. This group is not very well-studied in Singapore, and hence there are probably many species that are not recorded.

Dendrophyllia sp.
Dendrophyllia spp. can appear very similar to the previous species, as they can also come in bright colours, and may have circular to oval corallites. They can, however, be differentiated by their fused septa, forming Y-shaped patterns converging towards the middle of the corallite. The polyps are usually larger than those of the previous species as well. This group is also not very well-studied in Singapore.

Family Caryophylliidae

Caryophylliid corals have prominent polyps which conceal the skeleton when they are extended. The polyps are usually thick and inflated in the day, but deflated when it gets dark.

Euphyllia spp. have fleshy tentacles with U-shaped tips, rounded tips or branching tentacles with both. Those with U-shaped tips are often called anchor corals. The corallites lack a columella, and the septa are prominent and smooth-edged. The corallites are trumpet-like with separate walls, and have rounded, meandering or branching outlines.

Plerogyra sinuosa
Plerogyra sinuosa is the only species of its genus that has been recorded from Singapore. It has bubble-like vesiclesIt has trumpet-like corallites with separate walls. I have only seen this while diving in local waters, but never in the intertidal area.

Physogyra lichtensteini
Physogyra lichtensteini is the only species from its genus that has been recorded from Singapore. It has bubble-like vesicles, but often with pointed tips. The colonies have corallites with meandering outlines and short, widely spaced valleys. It appears to be uncommon in shallow waters, as I have only seen it a few times in the intertidal area.

Family Faviidae

This is the largest family of hard corals in the world with more than 25 known genera. Many faviids have massive, boulder-like colonies, while others can be encrusting, plate-like, columnar or even branching. The family name comes from the Latin word favus, which means "honeycomb", as many faviids colonies consist of tightly packed, small rounded or angular corallites which give them the "honeycomb" appearance.

Caulastrea spp.
Caulastrea spp. generally have phaceloid colonies (with trumpet-like corallites). It may resemble Lobophyllia corals, but unlike the latter it lacks the sharp, protruding teeth found on the septa of the latter. The polyps may have lighter-coloured stripes on them.

Cyphastrea spp.
Cyphastrea spp. generally have small, round, protruding coralllites (smaller than 0.5cm) with separate walls, prominent septa and columella. There are 10 primary septa (check for thick and complete ones).

Oulastrea crispata
Oulastrea crispata is the only species in its genus, and is easily recognised by the small encrusting colonies, black coenosteum and protruding corallites with white septa.

Diploastrea heliopora
Diploastrea heliopora is also the only species of its genus, and can be identified by the shallowly dome-shaped corallites, very thick walls, and small openings.

Favia spp.
Favia spp. have corallites with separate walls, though in some species (like above) they may be very tightly packed. The colony grows by intratentacular budding, and hence some corallites may appear peanut-shaped as they are splitting. They usually form boulder-like colonies.

Favites spp.
Favites spp. have corallites with shared walls, and usually no paliformed lobes. They usually form boulder-like colonies.

Goniastrea spp.
Goniastrea spp. also have corallites with shared walls, but have well-defined paliformed lobes. The corallites may appear rounded or elongated, with a maze-like appearance.

Leptoria spp, Platygyra spp. and Oulophyllia spp.
Several other coral genera have maze-like appearance, and they include Leptoria spp, Platygyra spp. and Oulophyllia spp. Unfortunately I did not have closeup photos of the above corals, and hence could not identify them. Generally, Leptoria spp. usually has narrow (less than 0.4cm) but strongly parallel "valley and ridges", and the columella is a solid wall. Platygyra spp. generally have more ragged wall with exerting septa, have no paliformed lobes, and the columellae come in a continuous tangle of spines. Oulophyllia spp. have thinner septa, the valleys are short and wide, and paliformed lobes and/or columella are present.

Echinopora spp.
Echinopora spp. are rather different from most other faviid corals in local waters as they usually exhibit a plate-like and/or branching growth forms. They can be mistaken for Echinophyllia spp. or Oxypora spp., but has granulated coenosteum instead of the spiny ones found in the latter two species.

Family Fungiidae

Fungiid corals are mostly free-living and solitary as they mature, though there are several sessile and/or colonial species too. The juvenile free-living species are attached to the substrate by a stalk, and together with their gill-like septa, they somewhat resemble mushrooms, and hence they are often called mushroom corals. As they mature, they will eventually break away become free-living. They move by taking in more water into their body and shifting with the currents. Unfortunately I do not have clear photos of the sessile species, and hence will only highlight the motile species here.

Fungia spp.
Fungia spp. are solitary animals, i.e. , every “mushroom” is a single huge polyp sitting in its own corallite by itself. They are among the biggest coral animals, reaching up to 20 cm in diameter. Depending on the species, they can be circular or oval-shaped, and hence the common name "disk mushroom coral", but the mouth is usually located in the middle of the corallite. The tentacles are short, and are fully retractable.

Heliofungia actiniformis
Heliofungia actiniformis, commonly known as the sunflower mushroom coral, is also disk-shaped but has long tentacles with white tips that are always extended and never fully retracted. They are sometimes mistaken to be sea anemones, but unlike the latter, they have a hard skeleton and are free-living. This coral is the only species of its genus.

Ctenactis spp.
Ctenactis spp. were previously placed under the genus Fungia. The shape of the skeleton is oval or oblong, and they can have one or multiple mouths along the groove in the middle (called the fossa). The septa have obvious saw-like teeth.

Herpolitha limax
Herpolitha limax is a free-living colonial species, and each colony has several polyps in the axial groove in the middle, and smaller polyps in the grooves by the sides. They are commonly called boomerang corals as the colonies can be boomerang-shaped sometimes, but mostly they are oblong. Sometimes, Y-shaped or X-shaped colonies can also be found.

Polyphyllia talpina
Polyphyllia talpina is the only species in its genus. It is also a colonial species, with numerous polyps distributed over the upper surface of the colony, which can be oval, oblong or boomerang-shaped. The finger-like tentacles have white tips.

Family Merulinidae

Merulinid corals have corallites with fused walls, forming bumps or ridges. This family exhibits a variety of growth forms, and the colony may be massive (boulder-like), encrusting, plate-like, branching or columnar.

Merulina spp.
Merulina spp. usually form plate-like or encrusting colonies with short straight valleys running towards the edge, spreading out like a fan. In bigger colonies, branch-like or columnar structures can be seen extending out from the middle of the colony.

Hydnophora spp.
Hydnophora spp. have distinctive small ridges and bumps (or hydnophores) covering the surface of the colony, formed by fused walls of adjacent corallites. The tentacles are short and surround the hydnophores. The colonies may be branching, encrusting or boulder-like.

Family Mussidae

Mussid corals generally have thick and fleshy polyps, and large corallites with thick walls. The septa are lined with sharp, protruding septa teeth. They usually feed on zooplankton at night. Many mussids have thick meandering ridges on the surface of the colony, giving them a brain-like appearance, and hence these corals are also commonly called brain corals.

Symphyllia spp.
Symphyllia spp. are usually found in massive (boulder-like) colonies with wide valleys and thick meandering ridges (more than 1cm) form by fused walls. A narrow groove can usually be found on top and between the two fused walls. Sharp septa teeth can on the fused walls.

Lobophyllia spp.
Lobophyllia spp. have big and fleshy polyps and big corallites with separate walls. Like the previous genus, they have sharp septa teeth, differentiating them from other similar-looking corals with trumpet-like corallites forming submassive colonies.

Acanthastrea sp.
Acanthastrea spp. form massive but flattish colonies. The corallites have shared walls, and are circular or angular in shape. The septo-costae, which are marked with sharp teeth, are thicker nearer to the wall, but thinner near the columella. The polyps are big, thick and fleshy, and usually marked with bead-like fleshy structures on the surface. They can sometimes be confused with corallimorphs, but can be differentiated by their hard skeleton and septa teeth, which corallimorphs lack.

Family Oculinidae

Oculinid corals have crown-like corallites with sharply pointed septa. The tentacles have prominent white tips, somewhat resembling a galaxy of stars, and hence they are commonly called galaxy corals. They appear to be quite tolerant of sedimentation, and can occur in large colonies on our reefs.

Galaxea spp.
Galaxea spp. are represented by two species in Singapore: Galaxea astreata (main picture) with uniformly circular corallites; and Galaxea fasicularis (right-bottom) which has both round and oblong or oval corallites. Both species have crown-like corallites with protruding septa teeth, and white-tipped tentacles.

Family Pectiniidae

Pectiniid corals often exhibit a plate-like or leafy appearance. Many species produce a lot of mucus, possibly to gather and remove sediment from the colony. Most species have long sweeper tentacles for feeding.

Pectinia spp.
Pectinia spp. are often called lettuce corals for their leafy, lettuce-like appearance. The surface is irregularly covered with numerous thin septa.

Oxypora spp. or Echinophyllia spp.
Oxypora spp. and Echinophyllia spp. are two very similar-looking groups of corals from this family, and I am still unable to differentiate them. They usually form encrusting or plate-like colonies with round or oval corallites. The surface of the colony is usually covered with spiny structures, instead of the granulated surface found in the similar-looking Echinopora spp.

Family Pocilloporidae

Pocilloporid corals often exhibit branching growth forms. The polyps are small, and when they are extended they form a "furry" layer over the colony

Pocillopora damicornis
Pocillopora damicornis is one of two species of this genus that can be found in Singapore. This species can be recognised by the scar-like patterns of the corallites. The other Pocillopora species generally have verrucae (cone-like bumps) on the surface of the colony.

Family Poritidae

Poritids corals generally have small corallites with shared walls.The columella is present.

Porites spp.
Porites spp. have tiny and inconspicuous polyps and corallites forming tiny depressions on the surface of the colony with complete septa and columellae. They usually exhibit massive, columnar or branching growth forms.

Goniopora spp.
Goniopora spp. are sometimes mistaken for sea anemones due to their long and fleshy polyps concealing the skeleton. Each polyp have 24 tentacles, and the colonies may be submassive, massive or encrusting. They are very similar to corals of the genus Alveopora from the same family, but the latter has 12 tentacles per polyp.

Family Siderastreidae

Siderastreid corals may occur in leafy, plate-like, columnar or encrusting forms. The corallites have poorly defined walls and the septa are usually partially fused to form fan-like groups.

Psammocora spp.
Psammocora spp. have corallites which form tiny petal-like structures on the surface of the colony. Depending on the species, the colony may be columnar, encrusting, submassive, or leafy in appearance.

Pseudosiderastrea tayami
Pseudosiderastrea tayami is the only species in its genus. It usually forms small, encrusting (at most slightly dome-shaped) colonies. The corallites have shared walls, and are polygonal in shape. The septa are usually fused with each other in fan-like groups.

Family Trachyphylliidae

Trachyphylliid corals have huge polyps, large paliformed lobes and fine septa teeth.

Trachyphyllia geoffroyi
Trachyphyllia geoffroyi is the only member of this family in Singapore. It has thick fleshy polyps and big corallites with thick walls. The juvenile is attached to the substrate, after which it will clone itself to form a colony and break away to become free-living. It is sometimes called the open brain coral, due to the many gaps among the brain-like colony.

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