Description
Image from National Geographic
The Caretta Caretta sea turtle is commonly known as the 'Loggerhead' due to their overly large heads and thick, horny beaks compared to other sea turtles. It has a hard shell and is the largest of all the hard shelled turtles.
The shell is a reddish brown colour and the front flippers have two claws, these can be seen in the picture on the left. Their skin ranges from pale yellow to brown with a mottled appearance.
A fully grown adult can weigh up to approximately 100 kg and be over a meter in length.
These beautiful creatures can reach speeds of 24 km/h when effortlessly gliding through the water but are rather ungainly and slow on land. Turtles that have had trackers fitted have been known to travel nearly 5000 km in their search for food before returning to their nesting ground.
The shell is a reddish brown colour and the front flippers have two claws, these can be seen in the picture on the left. Their skin ranges from pale yellow to brown with a mottled appearance.
A fully grown adult can weigh up to approximately 100 kg and be over a meter in length.
These beautiful creatures can reach speeds of 24 km/h when effortlessly gliding through the water but are rather ungainly and slow on land. Turtles that have had trackers fitted have been known to travel nearly 5000 km in their search for food before returning to their nesting ground.
Life History Of The Loggerhead Turtle
Image from nmlc.org
As a tiny embryo within its egg the sex of the Loggerhead is determined by the temperature of its environment. The incubation temperature generally ranges from 26 - 32 degrees Centigrade. Those eggs which incubate at the higher range of temperatures generally become females, whilst those incubated at the lower end of the scale become males. This means that in most cases the turtles hatched at the top of the egg chamber are females.
Anywhere between 50 -80 days after being laid, the hatchlings first begin to break out of their shells and dig their way to the surface. This usually occurs at night, but as can be seen by the video on this web-site, it can happen at any time of day. The hatchlings make their way to the brightest source of light, normally the ocean. Unfortunately, due to our passion for lights along beach fronts, the hatchlings can get confused and make their way inland. This is why we shade the nests.
The lucky ones who make it to the sea without getting lost or being picked off by predators use the natural undertow of the water to pull them out the first few metres. Their trek from the nest to the sea allows each hatchling to develop their lungs and muscles, an essential part of the process as they will swim for about 20 hours to reach the relative safety of the deeper seas. Without this walk the hatchlings may drown due to their underdeveloped musculature and lungs.
Juvenile hatchlings will hide amongst clumps of floating seaweed and other debris. This is a good source of food for the young turtles and provides protection from many predators at this vulnerable stage. Once the juveniles reach about 45cm (18 inches) in length they move from this slender protection and start to swim nearer shore in their search for food and later in life, mates.
Loggerheads occupy waters with a surface temperature ranging from 13 - 28 degrees Centigrade and rarely come ashore except to nest. The male may never come ashore at all. They can reach sexual maturation at around 17 years old and the whole cycle will begin again. The female will return back to the same area of coastline where she was born to mate and lay her own eggs.
Anywhere between 50 -80 days after being laid, the hatchlings first begin to break out of their shells and dig their way to the surface. This usually occurs at night, but as can be seen by the video on this web-site, it can happen at any time of day. The hatchlings make their way to the brightest source of light, normally the ocean. Unfortunately, due to our passion for lights along beach fronts, the hatchlings can get confused and make their way inland. This is why we shade the nests.
The lucky ones who make it to the sea without getting lost or being picked off by predators use the natural undertow of the water to pull them out the first few metres. Their trek from the nest to the sea allows each hatchling to develop their lungs and muscles, an essential part of the process as they will swim for about 20 hours to reach the relative safety of the deeper seas. Without this walk the hatchlings may drown due to their underdeveloped musculature and lungs.
Juvenile hatchlings will hide amongst clumps of floating seaweed and other debris. This is a good source of food for the young turtles and provides protection from many predators at this vulnerable stage. Once the juveniles reach about 45cm (18 inches) in length they move from this slender protection and start to swim nearer shore in their search for food and later in life, mates.
Loggerheads occupy waters with a surface temperature ranging from 13 - 28 degrees Centigrade and rarely come ashore except to nest. The male may never come ashore at all. They can reach sexual maturation at around 17 years old and the whole cycle will begin again. The female will return back to the same area of coastline where she was born to mate and lay her own eggs.
Predators
Image from Virtual Tourist.com
As an adult the Loggerhead turtle is very rarely attacked by natural predators due to their size, but sharks, killer whales and seals have all been known to attack full grown Loggerheads.
Unfortunately predators are abundant for every other stage of the turtles life, from egg to juvenile.
Eggs are preyed upon by everything from certain types of insect to cats, dogs, snakes and birds. In some areas of the world man also hunts out nests for the eggs, but luckily in Crete this is not the case. Hatchlings are at risk from birds, crabs and a host of small animals on their trek to the sea and the problems do not finish when they reach the relative safety of the ocean. Once in the water moray eels, parrot fish and crabs will all strive to make a meal of the young turtles.
While man is not a natural predator, many Loggerheads die each year in unattended nets and long line fishing lines. Another cause of death to the turtles is the rubbish we throw away. A plastic bag can look a lot like a jellyfish to a Loggerhead turtle, and once swallowed can block the intestines causing a slow, painfull death.
Unfortunately predators are abundant for every other stage of the turtles life, from egg to juvenile.
Eggs are preyed upon by everything from certain types of insect to cats, dogs, snakes and birds. In some areas of the world man also hunts out nests for the eggs, but luckily in Crete this is not the case. Hatchlings are at risk from birds, crabs and a host of small animals on their trek to the sea and the problems do not finish when they reach the relative safety of the ocean. Once in the water moray eels, parrot fish and crabs will all strive to make a meal of the young turtles.
While man is not a natural predator, many Loggerheads die each year in unattended nets and long line fishing lines. Another cause of death to the turtles is the rubbish we throw away. A plastic bag can look a lot like a jellyfish to a Loggerhead turtle, and once swallowed can block the intestines causing a slow, painfull death.
Nesting
In the Mediterranean it is Greece that proves the most popular area for the nesting Loggerhead turtles with approximately 3000 nests along its coastline each year (spotila 2004, p166).
Unfortunately the number of nests is in decline due to many natural factors, but mainly due to mans influence on their nesting environment. The Loggerhead does need all the help it can get to produce hatchlings from its nests.
Only the female Loggerhead will come ashore to nest. Usually at night she will exit the sea and make the arduous climb up the beach. The female will then scrape away the top layer of pebbles and sand to make a body pit to lie in whilst laying her eggs. With her hind limbs she will then dig out an egg chamber where she will deposit her eggs. After laying her eggs she will carefully cover it over with sand to camouflage the nest before returning to the sea. The whole process can take up to 4 hours to complete.
The same Loggerhead turtle can do this 4 or 5 times each nesting season with an average egg count in each nest of 70 eggs. Between 49 - 79 days after laying the eggs, all being well, the first hatchlings should appear and start making their way to the sea.
These hatchlings will return to the same stretch of beach to lay their own eggs once they reach sexual maturity, 17 years or so later.
Unfortunately the number of nests is in decline due to many natural factors, but mainly due to mans influence on their nesting environment. The Loggerhead does need all the help it can get to produce hatchlings from its nests.
Only the female Loggerhead will come ashore to nest. Usually at night she will exit the sea and make the arduous climb up the beach. The female will then scrape away the top layer of pebbles and sand to make a body pit to lie in whilst laying her eggs. With her hind limbs she will then dig out an egg chamber where she will deposit her eggs. After laying her eggs she will carefully cover it over with sand to camouflage the nest before returning to the sea. The whole process can take up to 4 hours to complete.
The same Loggerhead turtle can do this 4 or 5 times each nesting season with an average egg count in each nest of 70 eggs. Between 49 - 79 days after laying the eggs, all being well, the first hatchlings should appear and start making their way to the sea.
These hatchlings will return to the same stretch of beach to lay their own eggs once they reach sexual maturity, 17 years or so later.