Subject:
A pair of Tiger Cardinalfish (Cheilodipterus macrodon) meddles with a shoal of Crown Squirrelfish (Sargocentron diadema).
This Cardinalfish species, one of the largest in its family, is a predator of small fish. It can reach a total length of 25cm/10in but is usually encountered in smaller sizes. The Tiger Cardinalfish is widespread in the waters of the Indo-Pacific region, where it is found at a depth of up to 40m/120ft.
The Squirrelfish mainly feed on crustaceans, mollusks, and gastropods, and pose no threat to smaller fish species. However, any small fish believing they are safe in the vicinity of squirrelfish are hopelessly deceived, as the Tiger Cardinalfish, disguised by its red and white stripes mimicking the squirrelfish, poses a threat to them.
The Tiger Cardinal fish are like a wolf in sheep's clothing. For the Tiger Cardinalfish to successfully deceive small fish species, they also need to share the same habitat and distribution as the squirrelfish, which they do.
This form of mimicry reminds me of the Brothers Grimm’s fairy tale of The Wolf and the Seven Young Goats, where the wolf smears white flour over its coat, turning his black feet white. When the little goats see his white feet and hear his sweet voice, they open the door. The wolf then jumps into the house and gobbles up six of the little goats. The famous fairy tale of Red Riding Hood also has some resemblance to this mimicry, where the wolf, disguised as the grandmother, jumps out of the bed and eats the little girl. Many similar stories exist in different parts of the world, where one is deceived by some sort of masquerade. Although it is impossible to prove, one can assume that these stories are based on many different observations in the natural world.
There are many theories about mimicry, and different forms of it have been observed in many different animal and plant species all over the world. These masquerades are a product of evolution and have evolved slowly over millions of years as a result of genetic mutations caused by damage or replication errors in an organism's DNA. Although it may appear that an individual is copying certain characteristics of another, these mutations are always random and not planned. If these mutations are beneficial, the offspring is more likely to survive and reproduce, if not a species will go extinct.
Technique:
A lot of suspended particles in the water column, resulting from a few days of heavy rain, made filming conditions difficult on the day this underwater videoclip was filmed. Positioning video lights too close to the subject generates a lot of backscatter (light reflecting on suspended particles), while positioning them too far away underexposes the subject.
With some trial and error, I managed to set up the video lights so that the backscatter was reduced to a minimum, yet the fish were still illuminated enough to bring out the red colour in their scales. Noise-reducing software was applied in post-production to reduce the adverse effects of the water conditions.
Filming location:
This short underwater videoclip has been filmed in Mauritius 🇲🇺
For another in-depth description about another Cardinalfish species with stripes please go to our vlog post 85 or click on this link: https://www.beyondscuba.com/post/a-cardinalinhispyjamas
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