MARINE CONSERVATION CENTRE
WHO ARE THEY?
Turtle-like creatures first appear in fossil records from 200 million years ago. The turtles we see today remain relatively unchanged over the last 110 million years. There are now roughly 250 species of turtles, tortoises, and terrapins, of which 7 are sea turtles.
The largest living species of sea turtle is the leatherback The largest specimen was found off the coast of Wales in 1988 and measured 3m. However, the largest species of sea turtle that ever lived was called Archelon and measured 5m from snout to tail. This species lived about 70 million years ago.
There are 7 different types of sea turtles.
Caretta Family Members
Caretta Caretta
Eretmochelys imbricata
Chelonia mydas
Lepidochelys kempii
Dermochelys coriacea
Lepidochelys olivacea
Natator depressus
There are 2 two species of sea turtles nesting on Turkish coasts. One of these, the loggerhead sea turtle (Caretta caretta) is carnivorous, and the green sea turtle (Chelonia mydas) is herbivorous.
In the Manavgat region, which we have taken under protection, a large number of Caretta caretta species come to lay their eggs.
Basic biology
Sea turtles are reptiles. They are covered with protective plates, they breathe air into the lungs and reproduce by laying amniotic eggs. Amniotic eggs are eggs with fluid-filled sacs with soft but tough calcareous shells that protect the embryo from dehydration.
Sea turtles are cold-blooded (ectotherms). This means that they cannot regulate their internal body temperature and instead rely on their surrounding environment. A layer of fat under the carapace insulates the turtle’s insides, slowing down heat loss. Cold-blooded animals have lower metabolic rates and, as a result, require less oxygen than us meaning they can hold their breath and stay submerged for long periods of time – much longer than we can! A loggerhead turtle at rest can hold its breath for up to 10 hours, a green turtle for 4-5 hours, and a leatherback for about 30 minutes.
IUCN Redlist
IUCN (International Union for the Conservation of Nature) Redlist assigns a conservation status to species of plants and animals based upon current knowledge on population data, trends, threats, and other factors. The situation does not look good for sea turtles.
The Hawksbill and Kemp’s Ridley Turtles
Are Critically Endangered. It is actually estimated that there are fewer than 1,000 breeding female Kemp’s ridley turtles left in the wild.
Green Turtles
Are Endangered
Loggerhead, Leatherback, And Olive Ridley Turtles
Are listed as Vulnerable to extinction globally.
The Flatback Turtle
Is Data Deficient. That means 6 of our 7 sea turtle species are threatened with extinction if we don’t do something. For the ‘data deficient species, this means we simply don’t know enough about it to assign it a conservation status.
Sea turtles in trouble
The reason that sea turtles are in trouble is that they face a variety of threats:
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Targeted capture - International trade in all sea turtle species and their parts is prohibited under the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).
However, illegal trafficking still occurs. Turtles are slaughtered for their meat, skin, and shells, and they are vulnerable to poaching – especially their eggs, which are valuable on the black market. They are also killed for medicine and religious ceremonies.
Fisheries bycatch
This is thought to be the biggest threat facing the world’s sea turtles. Worldwide, hundreds of thousands of sea turtles a year are accidentally caught in shrimp trawl nets, on longline hooks, and in fishing gill nets. Sea turtles need to reach the surface to breathe, and therefore many drown once caught in the nets or on the line if they cannot reach the surface to breathe. Such untargeted fishing capture (bycatch) is a serious hazard for sea turtles.
Turtle Excluder Devices (TEDs) have been developed for trawl nets – global uptake has been slow, but progress is being made. Engagement with the fishing community is vital to ensure support and reduce the likelihood that TEDs are tampered with.
Marine debris
Pollution harms turtles at both population and individual levels. Poor water quality affects turtle health, and marine debris is a major cause of turtle deaths.
Plastics in the ocean are mistaken for jellyfish and ingested by turtles. Ingested plastics can damage the digestive tract and/or cause blockages leading to a slow and painful death.
Turtles can also become entangled in debris and drown. A disease called fibropapillomas, caused by pollution, is having a devastating effect on turtle populations.
Habitat loss
Sea turtles are dependent on beaches for nesting. Uncontrolled coastal development, vehicles on beaches and other human activities have directly destroyed or disturbed sea turtle nesting beaches around the world.
Green turtle feeding grounds such as seagrass beds are also at risk from coastal development onshore, which leads to pollution and sedimentation.
Climate change
Climate change has an impact on turtle nesting sites by altering sand temperatures, which could affect the gender of hatchlings and skew the sex ratio.
Warmer sea surface temperatures can also lead to the loss of important foraging grounds for sea turtles, while increasingly severe storms and sea level rise can destroy critical foraging grounds, nesting beaches and/or nests.
Boat strike
Because sea turtles must surface to breathe, they are at risk of being hit by passing speed boats/jetskis causing irreparable damage to the shell or skull. It is more difficult for the drivers of fast-moving vehicles to notice surfacing turtles, and react to avoid them in time.
Predation
Predation by feral animals is also a problem, particularly for new nests and hatchlings.
Why should we care if turtles disappear from our oceans?
Sea turtles have very important roles in the marine ecosystem. For example, sea turtles get cleaned by surgeonfish/tangs, so they rely on turtles for their food (parasites, algae & dead skin cells).
Batfish are often observed following turtles as they eat turtle poop. Remoras use turtles like free taxis, and also feed on their food scraps. Sponges make up the bulk of the diet of the hawksbill turtle with one adult eating an average of 1,000lbs annually. They help to ensure that sponges don’t outcompete corals by grazing on them.
They are a flagship species for the marine environment and by protecting them and their habitats we also benefit many other species.
Turtles are also culturally significant in some places around the world. They have an important role in many mythologies and religions around the world, especially in Asia and North America, and are often associated with creation myths.
In several religions, mythology and folklore from around the world, turtles symbolise wisdom, longevity, tranquillity and steadfastness.
The portrayal, and celebration, of marine turtles is also remarkable for its antiquity and diversity. Perhaps the oldest examples derive from the Middle East and the Arabian Peninsula, where cylindrical seals, stamps for decorating food preparations, reliefs on palace walls, and other cultural artefacts clearly depicting marine turtles are several millennia old.
They are much loved by children and feature in many animated movies (Finding Nemo – Crush & Squirt) and cartoons (Teenage Mutant Ninja Turtles – Leonardo, Donatello, Raphael & Michelangelo).