In April 2011, I spent a tad over 3 weeks diving several areas along the Wallace Line n search of some of these species.
There are parts of Indonesia that are special places, especially those that fall along what has been named by biologists as the Wallace Line. This imaginary line (actually it is defined geologically) separates the ecozones between Asia and broadly-speaking Australia. Along the line the biodiversity is exceptionally high and there are many rare, uncommon and distinctly unusual species.
LEFT: A purple phase Weedy Scorpionfish (Rhinopias frondosa) although brighly coloured is highly camouflaged amongst the surrounding coral rubble.
The water will be cold - I had been told....
I’d been warned that the water would be cold. Despite the warning, I still gasped as I fell from the boat into the 21 degree water. Considering I was diving in Indonesia, which straddles the equator, it was surprising to be almost suffering heat exhaustion on the surface and then to be exhibiting the mild symptoms of hyperthermia 10 minutes later.
LEFT: A purple phase Weedy Scorpionfish (Rhinopias frondosa). It's interesting that many fish cannot see colour, but can define tones. So, why is Rhinopias coloured so brightly.
I was diving in the region of Alor and Flores in search of unusual fish and nudibranches. In particular I was hunting (photographically speaking) a relatively uncommon and rare fish with the spectacular name of Rhinopias. I’d only seen fish belonging to this genus a couple of times when diving in Papua New Guinea, and on these dives I was unfortunate to not have my underwater camera with me.
Rhinopias sp. - An Unusual Fish Species
Rhinopias means “long nasal septum” and comes from the Greek and Latin translation. All species belonging to this genus have this same characteristic - a long slender snout leading to a huge cavernous mouth. What separates the different species is subtle characteristics such as the type and number of appendages, and size of pectoral fins, and the locations in which the fish is found. Colour and size, which can be controlled by food supply and environment. have no direct relationship to each species.
Cold Water & Muck Diving
The water was mind-numbing cold and despite wearing a full wetsuit, I found it i
ncreasingly difficult to maintain my vigilance searching along the muddy bottom for the prized fish. This area was not a beautiful reef in brilliantly clear sunlit water, but rather rocky substrate adjacent to a village populated by a few thousand Indonesians living an almost “hand to mouth“ traditional lifestyle. The visibility was limiting due to silt and debris entrained within the water column, and the bottom strewn with silt-covered boulders. This was one of the favoured habitats Rhinopias; this style of diving is what has been named by the diving community as “muck diving”.
LEFT (2 images): A Paddle-flap Scorpionfish (Rhinopias eschmeyeri). Note the different colour hue and the lack of white "highlighted" eyebrows to that of the same species in upper photograph; variation is common amougst Rhinopias sp.
Muck diving came of age after intrepid divers decided to begin to explore the not so often dived areas adjacent to bridges, rivers, marshes, wetlands and villages. You won’t the usual reef dwellers here, but you are liable to find the unusual, the ugly, and the strange. You may also come across the juvenile forms of many of the more common reef species, as these backwaters are a safer habitat for small fry.
To add to discomfort a chilly thermocline had developed at a depth of 25 meters and I was reluctant to sink into the shimmering layer as the water here was colder than the warmer water above. The shimmering water meandered its way across the rocky slope enveloping me for a minute or so before moving deeper; it was like going from a warm bath to a bath with floating ice cubes – then back again.
Why Are Rhinopias Special
Rhinopias is a genus of scorpionfish (Scorpanidadae) containing six species, and like other scorpionfish, utilise camouflage to blend in with their surroundings; I’ve always found it odd that a bright red, pink, yellow or purple fish can be almost invisible as you swim over it. Even when photographing the Rhinopias, I often find myself searching for the animal after swimming off a distance before making another run to take photographs - so good is nature to have provided such as tantalizingly beautiful veil of deception.
LEFT: A yellow phase Weedy Scorpionfish (Rhinopias frondosa) showing detail of the lure appendage over the cavernous mouth.
Rhinopias are rare fish, and sometimes appear in the aquarium trade, where they fetch high prices. They are lie and wait predators and generally are not fast swimmers. Their camouflage is unusual as the fish are brightly coloured over an often dappled base colour. This bright colouring however, doesn’t appear to offer any resistance to their reputation of being exceptionally dangerous bottom dwellers. To add to their concealment, are variously sized appendages which assist to breakup the visual outline of the fish and help disguise the large lips and mouth.
The appendage above the head of Rhinopias is used a lure and is often waved about like a small worm on a hook. Any interested passer by, stopping to investigate the waving appendage is quickly consumed as the fish opens its mouth and lunges quickly forward. The movement and opening of the mouth is enough to create a vacuum which sucks into the mouth any unsuspecting small fry.
Photographing Rhinopias
The most difficult part of photographing Rhinopias is actually finding the fish. Because this species often resides in silty and muddy environments, ensuring that the water remains as clean as possible is a photographer’s first task. Inappropriate fin movement and hand placement can completely envelope you and the fish with silt removing any opportunity you may have had to produce a good photograph. Therefore, good diving practices are required and neutral buoyancy must be maintained at all times; a somewhat trying task when swimming in a current.
Visibility was quite poor during this particular dive and despite being slack tide, the tidal current carried copious volumes of silt and debris from a the mouth of a nearby stream. Backscatter was a major concern and to minimise this backscatter (seen as bright spots in a photograph) accurate strobe placement is essential. I wanted the light from the twin strobes to just touch the fish and not illuminate the background water and entrained silt.
The photographs were taken with a Canon 5D MK2 in a Subal housing. The camera and strobes were set to manual to allow complete control over shutter speed, aperture and exposure.
Jostling With the Current
The current, heavy camera housing and twin strobes conspired against me as I jostled for a suitable shooting position. Several times I had to float past the fish, turn and swim back up-current for another run, because I was not in the correct shooting position. Everything from strobe placement, shooting angle, aperture and exposure had to be pre-visualised so as to acquire a successful photograph.
The prize photograph is a Rhinopias lunging with its mouth open, but despite repeated attempts none of the fish I observed appeared interested in doing this for the camera, despite being offered a few tender morsels as a reward!
In my next post dealing with this visit to Indonesia, we’ll look at some of the other bizarre creatures encountered whilst diving: crocodile eels, rare nudibranchs, colourful morays and frogfish.
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