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40. Juvenile Golden Trevallies (Gnathanodon speciosus) piloting a Pink Whipray (Pateobatis fai)



Subject:

Four juvenile Golden Trevallies (Gnathanodon speciosus) are piloting a Pink Whipray (Pateobatis fai previously known as Himantura fai) on a sandy patch in Mauritius.


The Golden Trevally is a relatively large fish, measuring up to 120cm/47inch in length and weighing as much as 15kg/33lb in its adult stage. This jack or mackerel is widely distributed in the tropical and sub-tropical waters of the entire Indo-Pacific region, but it does not inhabit the Atlantic Ocean. The golden colouration, hence its name, with black bars in juveniles fades to a more silvery colour with less pronounced bars as adults. However, their fins remain yellow, often with a greenish hue.


Piloting is the behaviour of swimming in front of, close to, or constantly following a bigger fish or big marine animals. Juvenile Golden Trevallies are known to mimic the looks and behaviour of the related black and white striped Pilotfish (Naucrates doctor) (both species are Jacks/Carangidae) by aggregating around bigger fish (usually sharks, groupers, or rays) and other big marine animals such as dugongs and sea turtles to enjoy protection from predators. Very small (or very young juveniles) also take shelter among the tentacles of jellyfish as a means of protection from predators.


Because of their symbiotic lifestyle with bigger marine animals, they might at times take up the role as cleaners. These Trevallies are toothless, relying on their big fleshy lips to swallow their food whole. The Golden Trevally is a foraging carnivore that filters feeds through its gills, extracting small organisms from sandy substrates; sand is expelled, and small organisms are trapped and swallowed.


The first part of the scientific name or binomial nomenclature of the Golden Trevally (called the generic name and identifies the genus to which the species belongs) comes from the Greek word “gnathos" meaning jaw and “aodus” meaning without teeth. The second part of their scientific name (called the “specific name” and distinguishes the species within the genus) is ‘speciosus,’ and it means beautiful in Latin.


Technique:

Because blue (the dominant colour in this clip) and yellow (the little Trevallies) are complementary colours (= any two colours that are direct opposites in the colour wheel), the juvenile Trevallies jump off the screen and easily catch the viewer's eye. Just a little enhancement of the contrast in the blue spectrum and a small increase in the saturation of the yellow was enough to make these images pop.


The sand and gravel sounds were added during the editing process and were not recorded during the filming of this clip underwater. These little beauties are quite easy to film. However, recording nice footage of these youngsters really depends on the fleeing distance of their host. When their host decides that it is time to leave the scene, the small aggregation of juvenile Trevallies follows without hesitation. To avoid spooking the host, a prudent approach as an underwater videographer or photographer is recommended.


Filming location:

This short underwater videoclip has been filmed in Mauritius 🇲🇺


More on this topic:

For a more in-depth description about the Pink Whipray please go to our vlog post 176 or click on this link: https://www.beyondscuba.com/post/a-pink-whipray-himantura-fai-swims-over-the-wreck-of-the-tug-ii

For a more in-depth description about flight distance please go to our vlog post 70 or click on this link: https://www.beyondscuba.com/post/flight-distance


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