A Simple Guide to Coral Basics


Coral is a complex, yet simply brilliant creature that lives in the ocean. They form beautiful reefs across the oceans and some look out of this world. They create such a beautiful and alien looking world that they have amazed people from all across the world. But what is this thing we have come to admire and love? What is coral? We all know what fish are, who Nemo and Dory are but what about where they live? Well within this post I aim to explain (in basic and simple terms) what the building blocks of our ocean’s reefs are by answering the question, what coral is?



Before I start let me explain that within this post there will simply be the very basics of what coral is and the most common types of coral within the aquarium industry. There is so much information that I could write about corals, what they are, how they feed, how they grow etc but that will be for later posts. For now I simply want to explain what coral is a non scientific manor.


I remember what I first started off with my aquarium and all I wanted was to have Nemo. So within a few months of setting my tank up, I got my very first clownfish and I called him… well you can guess.


Anyway after a while I saw all these beautiful plants and flower that I could put in my aquarium. So I asked in my local fish store what it takes to look after them. Long story short it turns out those ‘plants and flowers’ were actually coral and the man in the fish store didn’t laugh but simply explained to me what they were.  Which was great as I was a young child who simply was amazed by coral.


It was this simple explanation that got me hooked and in love with coral…and this is what he said…



“Son, Coral aren’t actually plants although I can see why you would think this. It is after all an underwater forest.

Coral are actually really tiny animals that together form colonies. These tiny animals are called polyps. You see that over there (pointing at an anemone)? well they look similar to that but much smaller. Some form large structures where they live together in huge numbers, almost like leaves on a tree.”



Now I know its not the best explanation or necessarily correct but in telling me the above he had opened a door I simply would never shut.

Basically he was correct. Coral are tiny animals called polyps. Some are reasonably large and can stand alone and others for hard structures and live in colonies. It is these hard structures that are the building blocks of a coral reef.



# Anatomy of a polyp


Coral are small creatures that have tentacles that surround a mouth, digestive system, reproductive tract and a nervous system. The tentacles of each polyp are tipped with tiny stinging cells that they use to defend themselves and/or capture food.



Above is a simple diagram of a single polyp. Although they may all look different and come in a range of sizes, the basic anatomy of a polyp is the same.

There are three main types of coral that are found in our oceans. These are Soft Coral, LPS (Large Polyp Stony) Coral and SPS (Small Polyp Stony) Coral.



# Soft Coral


Soft coral is what it is, its soft coral. This basically means the coral does not have a hard ridged skeleton and is able to move with the flow of the water, similar to grass in the wind. This type of coral is by far the easier to keep within the home aquarium and the ideal coral for beginners as they tend to be rather hardy. Its also my personal favorite type of coral as I love the movement in the flow and the colours are amazing.


Soft coral can live as an individual polyp or as a colony. When I say colony I simply mean a lot of polyps link together to form a larger coral, make sense? If not the photos should help.

Below is a photo of some soft corals that are single polyps such as Zoanthid and mushroom coral. Each individual coral is a single large polyp.



Mushroom Coral ^




Zoanthid Coral ^



Below is a photo of soft coral colonies such as the Kenya Tree Coral or the Sea fan.



Kenya Tree Coral ^



# LPS Coral


LPS coral stands for Large Polyp Stony coral. This type of coral tends to have a larger, fleshier polyp than other coral types. Unlike the soft corals LPS coral form a hard skeleton in which they live in and are able to retract into for safety. As a result of having a hard skeleton LPS coral need sufficient levels of calcium to grow properly. It is for this reason they are considered a harder coral to keep along with having a delicate fleshy polyp that is easily damaged.

There are many variations of LPS coral but the most common types within the aquarium industry are probably the Acan coral and Torch, Hammer, Frogspawn etc coral. They come in a wide range of shapes and sizes and can look beautiful within the home aquarium if their needs are met.



Hammer Coral ^




Acan Coral ^



# SPS Coral


Possibly one of the hardest corals to keep are the SPS corals. They need specific and stable water parameters which is often difficult to do within the home aquarium, even for the experts! SPS coral stands for small polyp stony coral and just like LPS coral these have a hard skeleton. If LPS are the flowers of a reef SPS are the trees.

They have a hard skeleton with hundreds of tiny polyps covering it. They come in all shapes and colours and truly are a beautiful addition to a reef aquarium if you know how to care for them. SPS corals are considered the goal within the hobby for many reefers.



Plate Coral ^




Acropora Coral ^


So there we have it, the very basics of what coral is.


Like I said in the beginning this is just a simple and basic explanation of the three main types of corals found within the home aquarium. For those who already knew this,


#1 – I did state this in the beginner!

#2 – I will be adding detailed posts about how they feed, how they grow, what species are in each type and how to care for each type in the near future. Trust me!


But for now I simply wanted to ‘open the door’ for the beginners out there, just like the man in my local fish store did for me all those years ago.


To see more images of corals why not check out our Instagram!

Its full of critters and corals from a selections of aquariums.