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The Kingdom of the Zulus is particularly rich in Sea Turtles and our divers often have the privilege of seeing these charming animals in their natural environment.

We have five species of turtles, three resident and two visitors.

Loggerhead Turtle (Caretta caretta)

An endangered species but one which is common in KwaZuluNatal's waters. The worldwide threat to the Loggerhead and the Leatherback is largely due to fishing and destruction of nesting sites. In Zululand, the indigenous population profit from 'turtle tourism' so that turtle fishing and the robbing or destruction of nests is not a problem, resulting in populations of Loggerhead and Leatherback Turtles increasing every year.

The Loggerhead has a shell of up to 1.20 metres with a total weight of 160 kilos. The shell is an orange/ brown and they have a relativelly large head and a powerful beak.

This species is largely carnivorous eating mainly crustaceans, sponges, fish and echinoderms but occaisionally also algae and marine grasses.

Sexual maturity is reached at 4 years. Every 2/3 years the female lays eggs up to 7 times between October and February each time around 120 eggs 40 mm in diameter, always at night and at the same site. We are not 100% certain but it seems that she identifies the site initially by her olfactory senses- her sense of smell. There are two theories-

1) The eggs during their development release pheromes into the sand which leach slowly into the sea. These pheromes are thought to guide the female to the nesting site.

Rivers which flow into the sea carry in suspension minerals, sediments and, unfortuneately, chemical pollutants which are specific to that area. It is thought that the 'aroma' of these materials helps the female to locate the nest area.

For both of these species, the incubation period is around 60 days but the amazing part is that the sex of the babies is controlled entirely by the ambient temperature during the first three weeks of incubation. If the ambient temperature during that period is below 24 degrees, there will be only male young. Above 29 degrees will give us only female young and between 24 and 29 degrees gives us a mix of sexes !!

After the 60 day incubation period, all the baby turtles break out of the eggs at the same time but remain recuperating from their efforts beneath the sand for 24 hours. The baby turtles take up less space when hatched than when they were in the eggs leaving a free space which gives them a reserve of air for their climb to the surface. This oxygen reserve is essential, especially for the Leatherback turtles whose nests are deeper than the other species. If the nest is too close to the high water mark, the sand's humidity reduces the available air reserve and all the babies die.

At a certain signal which we do not fully understand but which occurs always at night, all the baby turtles begin to dig for the surface. They mount en masse for the surface but if one is slower or weaker than the others, and does not keep up, it is buried and suffocates to death.

Arriving at the surface of the sand, the baby turtles march resolutely towards the greatest light source. On the Zululand beaches, this is inevitably the reflexion of the moon on the breaking waves and the babies march directly to the sea. Unfortunately in other parts of the world, this is not the case at all and the baby turtles, confused by man's artificial lights, are crushed crossing roads or simply never find the sea.

Leatherback Turtle (Dermochelys coriacea)

The second species which nests on our shores is the Leatherback Turtle. Again a species seriously endangered worldwide but, happily, increasing in numbers off Zululand.

The Leatherback is the largest reptile on the planet. It's carapace can be longer than two metres and the animal weigh 900 kilos. The carapace is not shell like other turtles but is cartilege covered in a kind of skin giving it the name 'Leatherback'.

The Leatherback has the most extensive migration of any turtle. The animals which nest on Zululand's beaches, migrate to False Bay near Cape Town -already 2,000 kilometres-before launching on a tour to the east of Madagascar before returning to our shores via the Mozambique channel. They move powerfully through the water using a movement of their front flippers more reminicent of a bird in flight than a sea creature.'

 

These powerful flippers can propel the turtle at a maximum speed of 9 km/hour and they can keep up speeds of 2.5 km/hour for enormous distances.

These enormous turtles live entirely on jellyfish and other soft bodied creatures.

This species, in Zululand at least, is much less precise in returning to it's nesting site than the Loggerhead. Between October and February, they nest six times but the site may vary by 40 kilometres. It seems that the Leatherback female locates the general nesting area by sensing pheromes in the water as does the Loggerhead but the exact nesting site is very much decided by the condition of the beaches. The contours of our beaches are constantly changing due to wave action. Due to her enormous weight, the Leatherback cannot cross reefs or unfavouably steep beaches so she uses the water movement close to the beach to locate a suitable exit point at which she can nest.

Green Turtle (Chelonia mydas)

The Green Turtle is resident on our coast but does not nest here.

In the nineteenth century, there were huge numbers of Green Turtles at Mauritius, Rodrigues Island, Agalega, La Réunion and the Seychelles but by 1900, they had virtually disappeared. Measures have now been taken to protect them and they are increasing in numbers in the French Europa Island in the Mozambique Channel ( where 10,000-18,000 females nest each year) as well as at Mohéli, the island of Tromelin and at St Brandon.

With it's heart shaped brown, olive or grey shell, the Green Turtle reaches a length of 1.50 metres and 250 kilos. They are 100% vegetarian grazing fields of algae. Unfortunately this diet gives the Green Turtle flesh a delectable flavour which is much appreciated by the island 'connaisseurs'. This is not helping in the preservation of the species !! On the other hand, research being done by the CEDTM and IFREMER on the French territory of Île de la Réunion is seen by our conservationists as a vital tool in assuring the continued wellbeing of the Green Turtle in the western Indian Ocean and is much appreciated by the Zululand diving fraternity.

 

 

Hawksbill Turtle (Eretmochelys imbricata)

The Hawksbill Turtle is the most endangered of all our sea turtles. In the 1800s the Island state of Madagascar exported 4,000 kilos per annum of Hawksbill Turtle shells. The trade is now officially banned but stocks continue to diminish.

This is a small turtle less than a metre in length and weighing a maximum of 60 kilos. It's heart shaped shell is reddish brown with yellow markings. It eats invertibrates, urchins, cephlapods, sponges as well as crabs and coral.

Ridley's Turtle (Lepidochelys olivacea)

The smallest of our sea turtles, the Ridley's barely reaches 0.8 metres and 45/50 kilos. The shell is as wide as it is long and well rounded.

It's diet is omnivorous preferring shrimps, molluscs, urchins, fish as well as algae.

Like the Hawksbill Turtle, the Ridley's is not resident on our shores but only a visitor. We do not have reliable statistics but the feeling is that their numbers are diminishing.

Our latest Pinnacles, Mozambique dive September 2017 Click

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