10 Mind-Blowing Facts about Marine Turtles

Updated: Nov 2, 2020

Turtles are some of the worlds' most loved sea creatures. And rightly so, it's so very easy to fall in love with their beauty and charm. If you've ever been lucky enough to see these majestic creatures gliding effortlessly through the warm waters of the tropics, you'll know just what I'm talking about. But there's a lot more to these angelic creatures than first meets the eyes.


1. ALL sea turtles are threatened with extinction

Worldwide, there are 7 species of marine turtle and ALL but one of these species are considered vulnerable, endangered or critically endangered. The flatback turtle (Natator depressus) being the only species exempt from this ONLY because the data is insufficient and scientists are unable to definitively say flatbacks are experiencing a downward trend in populations.



2. Temperature determines their sex

Scientists have been concerned about marine turtles for many years now, for a multitude of reasons. From plastic pollution to fisheries bycatch, turtles have a lot to overcome out there in the deep blue. However, possibly the most fascinating of them all is the impact global warming is having on the sex ratio of newborn turtles. When incubation of turtle eggs stays around 27°C, most babies will be born male. If incubation happens at 31°C then most will be female. And even more worryingly, after 35°C, most turtles will actually cook inside their shell and pass away. Not enough is known about how this gender ratio will impact future breeding opportunities for turtle populations, but it is likely that if global warming trends continue to increase, there will no doubt be a lack of potential male partners available for mating.


3. All the odds are against them

Unfortunately, I've got more bad news, because the damaging impacts of human activity on marine turtles become a lot scarier when you know only 1 in 1,000 hatchlings will survive to sexual maturity. This is the natural survival rate and does NOT take into account anthropogenic impacts such as global warming, plastic pollution or bycatch. To put this into context a Hawksbill turtle (Eretmochelys imbricata) can lay up to 200 eggs in one clutch. It would take 5 clutches of 200 eggs to produce 1000 eggs, and all of these eggs would need to hatch (which is virtually impossible due to naturally occurring threats like predation). This means not even 5 female hawksbills can produce 1 hatchling that will survive until adulthood.


4. Sea turtles are able to hold their breath for as long as 4 hours

Sea turtles spend the majority of their lives underwater, and will only venture onto land when the females need to lay their eggs. This means they eat sleep and do, well, pretty much everything in the ocean. Turtles have therefore evolved the extraordinary ability to hold their breath for up to 4 hours! Like many other diving animals, marine turtles are able to slow down their heart rate (some species to just 1 beat every 5 minutes when sleeping) to conserve the oxygen in their blood, allowing for such long breath holds.


Adult Hawksbill turtle (Eretmochelys imbricata) in Balicasag, Philippines.


5. The inside of their mouths is something out of a horror movie

Turtles don't have teeth to chew their food. Instead, they have 'papillae' lining their entire oesophagus. All these structures are directed down towards the stomach to aid digestion and swallowing. When a turtle grabs hold of a delicious jellyfish, it is inevitable that water will also end up in the mouth of the turtle. This isn't ideal, therefore the papillae 'grab' hold of their prey so the turtle is able to expel the water without letting the prey escape. It looks extremely terrifying and unexpected for such an adorable sea creature but they're extremely important!


Papillae inside a Leatherback turtles' (Dermochelys coriacea) throat (Source: CMAST)


6. Each is as unique as a snowflake

Turtles have specialised bony plates called scutes. These are all over their body, including their face. These facial scutes can be used to identify individual turtles as they are completely unique to each turtle. It is thought that an individual's scutes will not change as they grow old, meaning you could identify a turtle from hatchling till they're fully grown.


Green turtle (Chelonia mydas) at different life stages. It is thought that their facial scutes will stay the same throughout its life, therefore allowing researchers to track individuals as they grow.


7. Hatchlings are great at working as a team

Researchers have recently discovered that hatchlings are able to vocalise to their brothers and sisters that they are ready to hatch. This is how hatchlings are able to hatch en masse. They will use their 'egg-tooth' on the end of their beak (a 'caruncle') to break through their shell and their movements will also stimulate nearby eggs to hatch. Once enough turtles have hatched they then begin making a break for the surface, all together. A lone turtle hatchling would be unable to make it out of such a deep nest by itself, so this mass hatching allows them to work as a team and push up through the sand together.


8. They'll experience frenzied swimming for days

As soon as hatchlings break through the surface of the sand they experience an extreme surge of energy and will not stop moving until they make it to the ocean. This sprint for the ocean is vital as there are many predators such as frigate birds, who would love to munch down on a baby turtle. Energy absorbed from the yolk in their egg provides them with the energy to sprint to the ocean and sustain their frenzied swimming for roughly 3 days.


Hawksbill turtle (Eretmochelys imbricata) hatchings during their 'frenzied' stage. This can last for up to 72 hours.


9. The 'Lost Years'

From the moment hatchlings make to the ocean till the moment they come back as juveniles to forage and feed on coral reefs, no one actually knows what happens to them. These are called the 'lost years' and can be as long as a decade. Scientists are finding it very difficult to keep track of such small animals especially because their survival rate is so low. It has been hypothesised that young turtles swim out to favourable currents and find shelter under seaweed or ocean debris until they are old enough to come back to the reef, but this is only an educated guess.


10. They know exactly how to get back home

Turtles have an extraordinary way of finding the exact beach they were born on when they're ready to lay their eggs. After spending almost 30 years away from their natal beach, foraging on distant reefs and coastlines, they are still able to come all the way back to lay their eggs in almost the exact spot they once emerged from. Scientists believe turtles imprint on the 'unique magnetic signature' of their coastline, which they can then use as an internal compass.


From left to right: A young Green turtle in Balicasag, Philippines (Chelonia mydas), Hawksbill hatchling in Conflict Islands, Papua New Guinea (Eretmochelys imbricata) and a young Green turtle in the Philippines.


Cuteness overload! Couldn't write about turtles without adding this video in. Hawksbill hatchling (Eretmochelys imbricata).


Mimi x


Sources:


https://www.iucnredlist.org/species/14363/4435952


https://www.researchgate.net/profile/Charles_Caillouet_Jr/publication/310149939_Hook_and_line_bycatch_of_Kemp's_ridley_sea_turtles_Lepidochelys_kempii_along_the_Texas_coast_1980-1992/links/5829b4dd08ae509544735274/Hook-and-line-bycatch-of-Kemps-ridley-sea-turtles-Lepidochelys-kempii-along-the-Texas-coast-1980-1992.pdf#page=94


https://conserveturtles.org


https://www.cbc.ca/natureofthings/m_features/turtle-teamwork-sea-turtles-help-each-other-out-before-theyve-even-left-the


https://www.cell.com/current-biology/fulltext/S0960-9822(14)01638-8


https://bio.biologists.org/content/9/2/bio049247


https://www.nationalgeographic.com/news/2018/01/australia-green-sea-turtles-turning-female-climate-change-raine-island-sex-temperature/



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