A Starry Dragonet (Synchiropus stellatus) has turned these boulders into its playground.
The Starry Dragonet is a small, colourful dragonet belonging to the family Callionymidae (dragonets) and is native to the Indian Ocean. It is found in seaweed-rich areas and on algae-covered rocks, and can reach a length of about 7.5cm/3 inches.
Starry Dragonets, like all dragonet species, are benthic fish and lack a swim bladder; hence, they move around in a strange hopping manner.
The careful eye will have noticed a scorpionfish in the background. In fact, the area where these little colourful fish hop around is shared with many predators from the scorpionfish family (Scorpaenidae) and the stonefish subfamily (Synanceiinae). Reef Stonefish (Synanceia verrucosa), False Stonefish also known as Devil Scorpionfish (Scorpaenopsis diabolus), Decoy Scorpionfish (Iracundus signifer), Tasseled Scorpionfish (Scorpaenopsis oxycephala), and different Rhinopias species also live on these boulders. The local Starry Dragonet population doesn't seem to mind or be scared of these predators, which prey on small and medium fish species. There is a good explanation for the behaviour of both dragonets and predators: the Starry Dragonet's flamboyant red colouring is a form of aposematism that they exploit to defend themselves against these and other predators. It serves as a clear warning to predators not to eat them, as they produce a foul-tasting and foul-smelling secretion.
Starry Dragonets are carnivores and mainly feed on copepods and amphipods, which are very small types of crustaceans that live among the algae and seaweeds growing on this rocky Mauritian reef.
During courtship, the male Starry Dragonet, who is often more brightly coloured than the female, will show off his large dorsal fin. This dorsal fin is decorated with lines and sometimes with ocelli (round markings). The female's dorsal fin is black and ornamented with a white margin.
With its bright red colours, this little charismatic bottom-dweller really stands out against the algae-covered rocks. It was a beautiful underwater scene that I did not want to miss out on. However, filming this frantic hopping little Starry Dragonet between the big boulders of the reef proved to be quite a challenge. Barely 4cm/1.6 inches long, this flamboyant little gem challenged me at every stage. The large underwater camera rig with its long arms to hold the submersible video lights was very difficult to handle among these boulders. Each time I moved the underwater video camera forward a bit, the arms holding the underwater video lights were pushed backward against the rocks, disrupting the whole video lights setup. Sometimes, the flamboyant red dragonet would simply disappear in the gaps between the algae-covered boulders, only to reemerge a minute later or so.
The trick seemed to be trying to anticipate and predict the path of this little fish, in order to place the underwater video camera and lighting setup in a well-chosen spot and hope that the little critter would hop along the camera's lens. It was not only trial and error but also required a lot of patience and persistence, resulting in quite a nice outcome.
This short underwater videoclip has been filmed in Mauritius 🇲🇺
For a more in-depth description about aposematism please go to our vlog post 111 or click on this link: https://www.beyondscuba.com/post/inimicus-lll-aposematism
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