Sea Turtles

Green Sea Turtle from Sri Lanka

• Wide Distribution

Sea turtles are found in all the oceans except the arctic, and they all (except the Leatherback [Dermochelyidae]) belong to the order Chelonia. The seven living species are the flatback, green sea turtle, hawksbill, Kemp’s Ridley, Olive Ridley, leatherback and the loggerhead.

• Turtle Reproduction

Turtle are thought to navigate by the earth magnetic fields and usually return every 2 - 4 years to the beach where they were born to lay their eggs (2-300) in a 500mm deep hole scooped in the sand. Barely 1% of the hatchlings survive their instinctive scramble down to the sea, and the survivors need the shelter of banks of seaweed, etc to survive to become mature enough (about 30 yrs old) to start the breeding cycle again.

• Natural Protection

Their natural protective mechanisms include the ability to retract their heads inside their shells (-some retract legs and tails too); and can stay underwater for hours. They have excellent eyesight in water and are supposed to have a keen sense of smell for finding food in murky water.

• Endangered Species

Hunted for their flesh for the table, for their shell for decoration, etc, and their eggs for food, all sea turtles are now endangered;  with the leatherback, Kemp’s Ridley, and hawksbill turtles listed as critically endangered.  Even their nesting grounds are under siege with dune buggies, foreshore development, and pressure from deliberate egg harvesting. Inadvertant harvesting by heedless elements in the fishing industry adds a further toll.

Turtle and Tortoise Shell

• Tortoise Shell

As the name suggests this is simply material harvested from the scutes (Scales) covering the (Hawksbill) turtle carapace.  Formerly (in Victorian Era) very popular for making nick-knacks, ornaments and Pique (Jewellery inlaid with [precious] metal) work, it enjoyed a revival during the 60’s and 70’s and was used for making such things as combs, hair brush backs, sunglasses and knitting needles. Guitar picks made of this were very durable, and had the coveted degree of flexibility and bending properties .  The warm tactile quality of the shell made these items popular to the point where the Hawksbill Turtle is now an endangered specie. Trade in this shell was prohibited under the CITES treaty in 1973.

Victorian Pique Tortoise Shell Button

• Faux (false) Tortoise Shell

Tortex (TMDunlop) is one of several products developed to substitute for turtle and tortoise shell.  It mimics the color and patterns of tortoise shell and has achieved wide acceptance as a replacement product.

• Tortoiseshell (or Calico) Cats

This is a quite distinctively colored animal with black, orange, cinnamon, red or chocolate markings.  Almost exclusively female in gender these animals are not a specific breed but simply a not uncommon combination of two  X chromosomes. The rare males with this combination are usually sterile.

The color marking in the coat is asymmetrical, and often has clear tabby patterns.  Varying degrees of white are common as is the characteristic and popular ‘white mittens and bib’ pattern pictured to the right.

Turtles as Pets

If you intend to keep Turtle Pets you need to do a little research first, so your expectations will be met.  They are cute rather than lovable, and you shouldn’t expect it to play ‘Fetch’ - unless you are really good at waiting.  You need to discover some basic info about turtles so that you will have a clear idea about the space you will need to house the animal, what it needs for warmth (coolth?), shelter, and some idea of its diet.  Best advice - get a book!

• Food for Turtles

This is important info, because you will very soon have a very sick animal if you feed lettuce to a meat-eater who thinks a handful of worms put through the blender rates as ‘tops’! Get the facts first, and you will then be aware of the likely ‘running costs’ in terms of turtle fuel. And while we are on the subject, if it does get sick, take it to the vet, unless you are trained yourself.

• Terrariums

This is just a fancy name (Terra = Earth) for an aquarium type box without water - which might be the perfect home for the small turtle you plan to keep indoors.  They come in many sizes and there is a good range of gadgets (humidifiers, etc) available to make them environmentally friendly to your pet. A larger turtle will require an outdoor cage or house with a securely fenced yard for exercise.

• Owners Manuals

There are plenty of books available for the commoner types of turtle, and you may even find the ‘manual’ for your selected breed in your library. Do look for a book specific to your particular reptile.

• Preventive Maintenance

I know that is what you do to the car, but it works on turtles too!  Fresh water (or use a filter system if you are too lazy to change it); adequate food specific to your pets diet;  proper housing; and exercise plus some TLC (Turtle Wax?), and you have covered most of the things that will prevent your pet ever needing to go to the vet.

• Find Out

How big will it grow? How long does it live? Some species live longer then you do! Have a chat with your local pet-shop, they might be knowledgeable about these reptiles, and they will certainly know what local legislation you need to be aware of - some places have bylaws against keeping endangered or given rare species of turtles as pets.

Turtles, Tortoises and Terrapins

Turtles are reptiles (Chelonia) with most having a hard shell.  The definition of turtle or tortoise depends which side of the Atlantic you are on, and “terrapin” is usually only for the diamondback terrapin. They are cold-blooded, breathe air, and lay their eggs on land. Turtles that live on land have their eyes looking down at objects in front of them. Some aquatic turtles have eyes closer to the top of the head. They can hide from predators in shallow water where they lie hidden except for their eyes and nostrils. Turtles withdraw their neck into their shell while contracting it under their spine; or contract their neck to the side.

• Air Breathing and Cold Blooded

"Chelonia" from Ernst Haeckel's Kunstformen der Natur, 1904

Although many turtles spend large amounts of time underwater, all turtles and tortoises breathe air, and need to surface regularly to fill their lungs. They can also spend much of their lives on dry land. This means that quite a few turtles are suitable to be kept as pets. Underwater  respiration in Australian freshwater turtles is now being studied. Some types have cavities that can absorb dissolved oxygen from the water, much as fish use gills to breathe.

• Turtle Eggs

Sea turtles lay their eggs on sandy beaches. Young sea turtles are not cared for by the adults. They can take  years to reach breeding age, and in lots of cases only breed every few years.

• Legs and Flippers

Land tortoises have short, sturdy feet and are noted for moving slowly, partly because of their heavy shell but also because of the sprawling, legs bent gait that they have, rather than legs being straight and directly under the body, as is the case with mammals. Amphibious turtles normally have limbs similar to those of tortoises except that the feet are webbed. These turtles swim using four feet, similar to the dog paddle. Some, such as the Pig-nosed Turtle, have real flippers, with the ‘fingers’ being fused into paddles

• Turtle Shell

The upper shell of the turtle is called the carapace. The lower shell that encases the belly is called the plastron and are joined together on the sides by bridges. The inside of a turtle’s shell is made up of about 60 bones that includes portions of the backbone and the ribs, meaning the turtle can’t crawl out of its shell. In most turtles, the outer layer of the shell is covered by horny scales. The leatherback sea turtle and the soft-shelled turtles are covered with leathery skin instead.

Most tortoises have a large dome-shaped shell that makes it difficult for predators to crush the shell between their jaws. One of the exceptions is the African pancake tortoise which has a flat, flexible shell that allows it to hide in rock crevices. Most marine turtles have flat, streamlined shells which are helpful for swimming and diving.

• Green Turtles

Green turtles are large Sea Turtles, and their name derives from the green fat beneath the shell.  Green Turtles occur in sub-tropical and tropical seas.  There are two distinct populations, found in the Pacific and the Atlantic oceans..  Almost all are threatened by exploitation and sadly, now belong to the endangered species, although many countries now have legislation in place to protect the turtle, its eggs, and its [nesting] habitat.