This edition’s fish is one of the best known and most sought after photography subject on the reef, the Ocellaris Clownfish!
The Ocellaris clownfish, also known as the Common clownfish, Clown anemonefish or the False Percula clownfish, is one of the best known members of the Pomacentridae family. The Pomacentridae family has around 385 species containing the clownfish and the damselfish and are known for being highly territorial. They are most famous perhaps as the characters Marlin and Nemo from the ‘Finding Nemo’ films, however they would be a little different in real life, as we’ll talk about below!
The Ocellaris Clownfish
What’s in a name?
The Ocellaris clownfish gets its name from its eyes. The name ‘Ocellaris’ is Latin for ‘a little eye’ and was given to the fish because it’s eyes look every small. This is an illusion, however, as they have a large greyish/orange iris which matches their body colour. As it blends in from a distance, it looks as though the fish has tiny, pin-prick black eyes. The Amphiprion part is made of two Greek words; ‘amphi’ meaning ‘on both sides’ and ‘prion’ meaning ‘saw’. This refers the white bars on the flank of the fish.
Habitat and distribution.
Clownfish can be found on most tropical reefs around the world but the Ocellaris clownfish can be seen in the Eastern Indian and the Western Pacific. They are found exclusively on the reef to a maximum of around 15m. The main reason for this is that they live in a symbiotic relationship with sea anemones. Sea anemones rely on symbiotic zooxanthellae for some of their food, made via photosynthesis, meaning they need to stay close to the surface to receive as much sunlight as possible. They also tend to be found in more sheltered areas, such as lagoons and reef slopes out of strong currents.
Looks that kill.
Visually compelling, the Ocellaris clownfish is a perfect photography subject. Not only is the fish itself vivid and beautiful, the anemone can add a splash of colour to the background of your shot. As eggs they appear as a knobbly orange carpet underneath their parent’s anemone. If you approach carefully, you can clearly see the eyes of the fish inside the eggs as they develop. Once they have hatched, they already look like miniature versions of the adults, albeit with slightly less defined lines along their sides.
Let’s talk adults! They are a bright orange colour with three thick, slightly undulating white bars along their flanks. There is a thin black line along the outline of the white making them really pop out from the orange. These white bars help to camouflage the fish amongst the tentacles of the anemone that they are hiding in. They also have thin black lines along the edges of their fins.
As mentioned before, their iris is large and a similar colour to their bodies, making them appear small. This might be a way of confusing predators as to which end is the head end of the fish. There is another clownfish, called the Percula Clownfish (Amphiprion percula) which looks very similar to the Ocellaris but it has much thicker black lines and blotches along its body. There is, however, no difference between males and females.
A little about anemones.
One of the anemones that the Ocellaris clownfish is most often seen with is the Magnificent Sea Anemone (Heteractis magnifica). This looks like a deep purple coloured ball with creamy white tentacles. Alongside purple they can often be electric blue, lime green, pink red or chocolate brown. As it is a part of the Hexacorallia subclass, it has tentacles in multiples of six positioned in concentric circles. There’s a project for our budding biologists out there, why not try and count next time you see one! They can grow to approximately 50 cm across and can open or close their oral discs so either lots or few of their tentacles are on display.
Like a lot of the fish we have talked about in this series, Ocellaris clownfish are hermaphrodites. In this case they are protandrous hermaphrodites which means they are all born males with dormant female reproductive organs. The largest and strongest male becomes a female and keeps a harem of smaller males to breed with. This sex change makes more sense biologically than changing from female to male as producing eggs is far more energy consuming than producing sperm. Larger animals which are more successful hunters have more energy that they can spare to make the eggs.
The males form a social hierarchy, with the more dominant fish breeding with the female and the less dominant fish fighting to move up the queue. If the female dies, the most dominant and biggest male will change sex to become the female. So the next time you watch ‘Finding Nemo’ know that in the real world, Marlin would have changed sex and become Nemo’s mother before going out the find him!
The males also take care of the eggs once they have been laid, fanning them with their tails to keep water flowing over them and eating the dead or infected eggs.
Life on the reef.
Ocellaris clownfish are found on sheltered reefs and lagoons, wherever their anemone host can settle. These fish are not found without an anemone, any extended time spent away from it can lead to high levels of stress which can be fatal. They are diurnal, meaning they are active during the day and sleep at night. This is the same for the host anemone which can often be seen closed up on night dives. The clownfish eats algae and plankton that drifts past the anemone, some of which is eaten by the anemone itself to supplement the photosynthesis.
The Ocellaris clownfish, like other clownfish species, secrete a skin mucus that prevents it from being stung by the tentacles of the anemone. You can also see them wiping themselves on the mantles of the anemone to cover themselves in mucus from the host. This is believed to be a way of fooling the anemone into thinking the fish is a part of itself. The tentacles provide a great shelter for the fish from predators and in turn the clownfish defend the anemone from other fish trying to eat the tentacles. Ocellaris clownfish are highly territorial, often chasing and biting fish (and divers!) many times their size. They can be seen biting their reflections in camera lenses, mistaking the reflection for competing clownfish.
I always try to hunt out these little guys whenever I am in the area as they make for beautiful photo. Students love to see them on dives as well, any who are a bit nervous tend to relax when they see them. However, it is always worth approaching them with caution. They are very bold and have no problems nipping a diver that comes too close to them. A dive guide with me once had a chunk taken out of his finger by a large female after he pointed at her for too long! I will not give you too much photo advise myself as one of our photo pros, Mario Vitalini, wrote his own excellent article about it. I’ll put a link to it here, it’s full of advice for beginners and pros alike trying to nail these little guys down.
The bottom line.
Ocellaris clownfish are a delight to encounter on a dive. They are fun to watch for a while, flitting around in and out of the tentacles or you can spend hours trying to get that perfect photo. There is a reason why these little guys are so many divers favourite fish, few others have so much character!