Subject:
A Peacock Flounder (Bothus mancus) is scanning its surroundings with its elevated, protrusible eyes.
There is a lot that can be told about the eyes of flounders. First of all, all members of the suborder Pleuronectoidei, generally known as “flatfish,” are born with their eyes on both sides of their bodies, just like normal fish. However, all flatfish species like flounders, turbots, halibuts, and soles will undergo a strange metamorphosis; the fish is going to tilt its body to one side, going to live flat on one side on the sea’s bottom. As a result, the fish’s eyes will slowly migrate to the same side of the head in the adult fish. Some species will have both eyes on the left side, which is called sinistral or left-eyed, and other species will have their eyes on the right side; they are the dextral or right-eyed flatfish, and some species have their eyes migrating in either direction. The eye that makes the move is called the migrating eye.
Besides that, adult flatfish have one migrated eye; it must be said that both eyes are protrusible, meaning that they are able to move their eyes in an upward position, like a periscope, and retract them to the same height as the fish’s body. This retractable eyes on stalks feature is extremely handy for fish living on the ocean’s floor. By elevating the eyes, the flatfish is able to see much further than if the eyes were flattened on or embedded in their heads.
Another amazing feature of the flatfish’s eyes is that both eyes of these fish species can move independently, efficiently scanning the seafloor in search of food or to identify possible dangerous predators of flatfish. By doing so, they can have a near-complete view of their surroundings.
Adding to this the flatfish camouflage ability. Lying completely flat on the bottom, having almost the same colouration, and being able to cover their entire body with sand, they become almost invisible. Under some circumstances, of this Peacock Flounder, who can reach a total length of 45cm/18 inches or so, only the eyes on stalks would be the only part of the fish that can be observed by scuba divers.
Technique:
This particular flounder was filmed on a night dive. All the little crustacean-like critters that suddenly take-off are more than likely triggered into a frantic flight like an uncontrolled projectile by my submersible video lights. As I positioned the lights far enough away from my underwater videocamera’s dome, they are not much of a nuisance.
As I record my images at a 24fps rate, the beautiful effect of motion blur is enhanced. This is especially true near the end of this underwater videoclip in the very short part where the flounder takes off. The sudden hasty departure of the flounder stirs up the sandy bottom resulting in a beautiful motion blur of the flatfish and the grains of sand. This effect is only possible when filming in a low frame rate. If you would be filming in, for example, a 60fps rate, the motion blur would be much less obvious. This example is just one of the reasons that I prefer to film in the cinematographic frame rate of 24fps.
Filming location:
This short underwater videoclip has been filmed in Mauritius 🇲🇺
More about this topic:
For other in-depth descriptions about the Peacock Flounder please visit vlog post 180:
and vlog post 129:
Join us on a journey of discovery and entertainment as we explore fascinating marine wildlife topics and explore the many exciting underwater adventures on our YouTube channel and our Facebook page!
Unlock the power of marine wildlife videography and unleash your inner filmmaker with our online Marine Wildlife Videography course!