Saturday, August 19, 2017

Using the Coral Finder


Check out the learning pathway and training movies in the Learning Centre for tips on how to use the Coral Finder and the Coral Hub. This is the easiest way to learn.

Alternatively, this article provides a recipe or worked example of the 3-steps method for using the Coral Finder. Also, check out this early training movie –  it’s an oldie but a goodie!

To reliably identify corals it is important to confirm identifications made using the Coral Finder. Seeing the answer using the Coral Finder is a great way to get started, but it is also important to know why a coral is what it is. The Coral Finder and the Coral Hub were designed as complementary tools to help you move forward in this way.

What do you need?

Ideally to get into groove you will need:

  1. A warm, sunny day on a coral reef in either the Indian or Pacific Ocean (though sitting in your lounge chair next to your reef tank will do! 😉
  2. A copy of the Indo Pacific Coral Finder.
  3. A sheet or underwater paper, plastic clutch pencil and a cheap magnifying glass – all optional – see the Tips & Tricks movie.
  4. An underwater camera – again optional – but it will greatly assist your topside learning experience.

Note: if you find yourself landlocked and snowed in by a northern hemisphere winter then try:

  1. A cup of cocoa.
  2. A Coral Finder.
  3. Some pictures of corals.
  4. Another cup of cocoa!

The worked example starts here

The example assumes you have a Coral Finder in your hot little hand and that you are familiar with the terms in blue on the glossary page reproduced below. If you make the effort to learn these simple terms / concepts you will be able to use the Coral Finder to resolve around 70 genera regardless of growth form.

The simple glossary from the Indo Pacific Coral Finder (c)

The simple glossary from the Indo Pacific Coral Finder (c)

Step 1: select the Key Group most like your coral

So you are on a dive and suddenly you are confronted by a ferocious coral with meandering valleys! What do you do?

At a glance the grey target coral clearly has meandering valleys. Consult your coral Finder Key page!

At a glance the grey target coral clearly has meandering valleys. Consult your coral Finder Key page!

Step 2a: use the text on the Coral Finder Key Page to refine your selection and choose a Look-Alike page number

The Coral Finder Key Page offers an obvious selection here – the Meandering ridges and Valleys Key Group. Note that we now need to think about the scale of the corallites and the type of corallite walls. Have you read and understood the glossary?


The Meandering Ridges and Valleys Key Group on the cover page of the Coral Finder

In this example, you can see that neighbouring valleys have a common wall. With regards to the corallites size, just note the average valley width measured at right angles to the valley walls (we will discuss how to measure corals in another article). From top-to-top of the walls the valleys appear to average around 10mm across – sometimes more, sometimes less.

Always check the true scale of your coral first.

Always check the true scale of your coral first.

Step 2b: choose a Look-Alike page number

From the information we gleaned in the previous image we are favouring a beastie with a common walls and >10mm valleys. So lets try Look-Alike page 9.  (Note that variability is rampant in corals so if you weren’t sure about the valley width being greater than 10mm in this example, you could always quickly check page 8 anyway.  It’s quick, it doesn’t hurt and it’s free!)

Does it have separate of common walls? And how wide are the valleys?

Does it have separate or common walls? And how wide are the valleys?

Step 3a: go to the Look-Alike page, scan and confirm your coral genus

Using the tabs turn to page 9 and quickly scan your options. There are four genera displayed in the standard Coral Finder wideshot / midshot / closeup image grids. For those of you following along with your Coral Finder, it’s easy to dismiss Physogyra at the bottom (because our coral lacks daytime extended grape-like vesicles). Likewise a quick look reveals Symphyllia to be too fleshy and spikey for our customer.

So your choice quickly drops to two: Pectinia and Oulophyllia. Let’s look a bit closer.

Scanning Look-Alike page 9 for good candidates

Scanning Look-Alike page 9 for good candidates

Step 3b: Select the right genus

Underwater, with the benefit of 3D, the choice is fairly easy – Oulophyllia just “looks” like the “right” answer. Do a quick review of the text and tips in the characters section to help you learn and confirm. Oulophyllia has thicker walls and more regular septa than Pectinia. Remember colour is rarely meaningful in coral identification and if it is helpful the Coral Finder will say so.

A close up of the first two genera on page 9 of the Coral Finder

A close up of the first two genera on page 9 of the Coral Finder

Who is the coral in question?

Who is the coral in question?

Basic familiarity with corals

Take the time to look closely at corals and their detailed structure. Basic familiarity with corals counts for a lot. You need to get up close and see them in real life to improve your identification – take your Coral Finder for a snorkel or to an aquarium, and practice. Then find a way to see / handle some coral skeletons (in a museum perhaps) so that the terms in the glossary (above) become tangible and meaningful. The Coral Finder strips away most of the terminology that gets in the road of learning coral identification and replaces it with just ten or so terms / concepts. Make the effort with these basics and you will be able to separate about 70 genera of corals regardless of growth form.

Understanding the Coral Finder’s character description text

(see image Step 3b)

While Oulophyllia may “look” like the right answer we now need to confirm it is our genus using the Coral Finder’s character descriptions. The bold text highlights characters that are distinctive, though it’s the description as a whole that is important. Explanatory comments are in red.

Coral Finder: Domed or massive colonies.
Our field photo would have been “domed” originally but this colony has had a hard life and has become irregular.

Coral Finder: Valleys 10-20mm wide with sharp / narrow upper edge1 to valley walls. Septa regular & neat2.

Note: bold text means a “key character”. Superscript numbers refer to yellow “tip” arrows which point to that feature. Clearly, we are trying to point out that the corallite walls of Oulophyllia have a wider base; become narrower at the top and that the septa are regular and neat.

Coral Finder: Valleys larger / wider than Platygyra (CF p8); thicker walls and more regular septa than Pectinia (above).  

This text is designed to help you understand why Oulophyllia is a better choice than the other similar genera listed – again compare and contrast the characters.

Most people with a good eye for detail will just see / understand  that Oulophyllia and Pectinia are different. But by confirming and understanding the key characters you will be able to explain why those two genera are different. In effect you are training your mind to understand the science of coral taxonomy – which you will then be able to pass on to others. It is important to confirm the key characters to avoid making mistakes.  By confirming the characters you can collect high quality information about the corals of interest.

Summary of the Coral Identification process using the Coral Finder

Coral identification with the Coral Finder is a 3 step process.

  1. Select a Key Group

  2. Choose a Look-alike page

  3. Scan and confirm your coral genus

In our example:

  • the Key group is Meandering Ridges and Valleys
  • the Look-Alike page is a cluster of coral genera that fit the description: Meandering -> Corallites with Common  or Indistinct Walls >10mm
  • the Genus is Oulophyllia

Record your info on the Coral Finder’s slate (or on underwater paper). Take a photo to further your knowledge about your coral using the Coral Hub website.

Avoiding common errors

From teaching workshops with the Coral Finder we know that their are two main sources of error from early learners. To avoid mistakes:

  • always check the true scale
  • remember to confirm your findings with the character information on the right-hand side of the Coral Finder pages every time.


The MOST COMMON error is mistaken scale. An error of scale typically occurs where the user chooses a candidate genus that “looks OK” but doesn’t check that the scale of that coral is realistic. That is why the TRUE SCALE box is included for each genus in the Coral Finder with a bright orange border next to the text description and the close up. This problem is easily avoided. When you first look closely at a coral, check the width of its corallites using the scale bar provided on the inside back cover of the Coral Finder.  Scale is often required to choose a Look-alike page in any case so just get in the habit of checking the scale every time you first begin your coral interview. With this knowledge you can safely proceed to Step 3 of your identification. However best practice is to check the scale again at the final stage of making your determination. That’s because you will now have a Look-Alike page open with access to true scale images of all the potential candidates. Check the scale a second time – just do it – we beg you!


The second source of error may occur with experience and confidence. Because the Coral Finder empowers people to get the name of a coral very quickly and easily, people tend to rapidly improve their coral identification skills. The door opens to a new world.  The problem comes with what happens next. Everything is GOOD while your are following Coral Finder best practice which includes using the key characters to confirm your identification of each coral. After a while you may become tempted to jump to instant/confident recognition, i.e. you look at something and you say, “I know that – it is  X”, without checking the Coral Finder. It’s natural to do so, but with around 500 species all changing shape with environment there is scope for a few blunders along the way. The way to avoid this potential pitfall is to learn the key characters of similar genera and run through a mental checklist each time.

“There are more things in heaven and earth, Horatio, Than are dreamt of in your philosophy.”

WILLIAM SHAKESPEARE / Hamlet Act 1. Scene V abt. 1601


And so it is with corals.