It is common to see turtles whilst scuba diving around Koh Tao. In fact the island’s name – Koh Tao – translates from Thai as ‘Turtle Island’, (though I believe this is due to the topography of the island resembling a turtle, rather than the population of sea creatures).
One of the original settlers on Koh Tao, P’Wee (who has a dive site named after him), recounts a tale from many years ago. During night time, whilst he and his brother slept in a pit bed on the beach, a turtle crawled up out of the water and fell on top of them. Imagine!
Today we see two species of turtles around Koh Tao; Hawkbill Turtles and closely related Green Turtles.
Hawkbill Turtles are the most common turtle species around Koh Tao. They are distinctive due to the long head with curved beak, and saw-tooth edged shell. They typically grow to about 1 meter in length, weighing about 80Kg.
Though they can survive in colder environments, Hawbill turtles are mostly found in tropical waters. It’s understood that juvenile hawkbill turtles are pelagic (meaning they spend their time in the open sea). Then as the turtles mature, they spend more time in shallow coastal areas.
Around Koh Tao, we usually find Hawkbill Turtles relaxing and feeding around the shallow coral reefs. Their diet consists mostly of sponges, but not exclusively. They can also eat algae, jellyfish and anemones. This diet leads to a couple of astounding outcomes. The turtle’s ability to consume species which are poisonous to other marine life make Hawkbill Turtle’s flesh toxic. This in turn makes them an unattractive meal for most predators. And equally astounding, some of the corals which Hawkbill Turtles consume exhibit biofluorescence (glow in the dark). With prolonged consumption this phenomenon is passed onto the turtles, so they themselves have been seen to exhibit biofluorescence!
One significant difference between the Hawkbill Turtle and closely related Green Turtle is that Hawkbill Turtles move with an assymetrical gait (similar to the way humans walk). By contrast, Green Turtles use a more symmetrical motion.
Like most marine organisms, sadly the main threat to Hawkbill Turtles is the impact of humans. Fishing takes place and in some parts they are consumed as a delicacy. Combine this with their slow growth, late maturity to reproduction (typically 20 years) and slow reproductive rate and Hawkbill Turtles are now considered a ‘Critically Endangered Species’. It’s estimated that their population has declined by approximately 80% over the last century.
With a lifespan of up to 80 years, Green Turtles grow larger than Hawkbill Turtles, typically 1.5M long and can reach nearly 200Kg. They are also distinguishable by their short snout (rather than hooked beak). The name Green Turtle comes not from the color of their shell, but instead from a layer of fat separating their organs from their shell. This fat coloration is a consequence of their diet.
The distribution of Green Turtles is vast, found in both tropical and sub-tropical waters. They’ve been recorded in over 140 countries as far as 30°N and 30°S. Part of the reason for this is that Green Turtles perform huge migration patterns, alternating between breeding grounds and feeding areas. Remarkably, Green Turtles have been recorded making migrations of up to 2600Km. That’s pretty good underwater navigation skills!
Breeding grounds are beaches. Amazingly, some Green Turtles return to the same beach where they were born. Meanwhile for feeding, Green Turtles prefer shallow bays in coastal waters which are rich in their preferred foods.
Interestingly, juvenile Green Turtles are predominantly carnivorous. As they shift towards maturity their diet switches to be more herbivorous, favoring sea grass and algae.
Like all turtles, they need to surface to breathe air periodically. Green Turtles can stay submerged for an amazing 4-5 minutes on a single breath.
Similar to their relatives, Green Turtles are considered an endangered species. And again, the main threat to their survival is humanity. As above, Green Turtles are considered a food source, so fishing and egg poaching take place. Plus building developments on coastal areas can destroy their breeding grounds. It’s now illegal to collect or harm green turtles, plus protected nesting areas are being established.
Scuba diving with turtles can be an amazing experience. But as discussed above, we need to be considerate in our activities to help protect these endangered species.
So a few quick guidelines to remember when scuba diving with turtles:
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