Looking into the Green Turtle's Eye (Chelonia mydas)...
Near-sighted on land, the Green Turtle's eyes are perfectly adapted to perform underwater. Red and orange colours are not seen well (as these are the colours that disappear first with depth), but the range from yellow to purple is well perceived. These are the colours that are most important to see at depth.
The Green Turtle only comes to the water's surface to breathe and occasionally to bask. This is also true for all other marine turtle species. Female turtles come out of the water to lay their eggs; male turtles will never venture out of the water. The only time when males are to be spotted out of the water is right after birth when they leave the nesting site and make a run over a sandy beach for the "relative" safety of the ocean. Once the little hatchlings are in the water, there is no imminent need to return to land. Females will return to that same beach where they first saw the light in their lives more than 25 years later or so to Digg a nest and lay their eggs. They will, however, repeat this every two weeks or so for a period of several months before returning to the safety of the deep. This egg-laying event will only take place every 2 to 5 years or so.
In an entire lifetime, the Green Turtle will only spend a fraction of its life near the surface and out of the water. This is probably why their eyes are more adapted to life underwater than for a terrestrial one.
Green Turtles and other species alike face a number of threats in our oceans. By-catch in commercial fisheries and entanglement in fishing gear (discarded nets, fishing hooks, etc.) resulting in drowning is probably the greatest threat to the survival of marine turtles. The poaching of eggs on nesting sites and the illegal hunt for adults also have a significant impact on the species' survival. Habitat loss and pollution are also reasons for the decline in turtle numbers worldwide. Vessel strikes and climate change are also having their impact on the survival rates of these herbivorous marine reptiles.
When filming bigger animals such as turtles, it is important to approach these animals cautiously. Any sudden or rushed movement will scare the animal and, therefore, result in an escaping subject.
There is something called the "flight distance," and for every animal, that distance is different. When a potential predator, or in our case, an underwater videographer or photographer, comes too close for comfort, the animal that perceives that threat will make a run for it. Fleeing critters won't make nice underwater footage anyway. Remember that underwater everything will outswim you; yet another reason not to chase animals. Get close to your subject without spooking it, move slowly, avoid jerky movements, and only then will you gain the animal's trust. Don't forget that with your scuba tank on your back, a big camera rig, and a constant repetition of air bubble bursts, you, as an underwater videographer are a big, noisy, and scary thing to most animals underwater. Once the animal is used to your presence, its fears are gone, and that trust is established; you can start filming.
This short underwater videoclip has been filmed in Mauritius 🇲🇺
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