Turtle

Turtle is an umbrella term used to define all types of shelled animals. Turtle and tortoise are the terms that are generally used interchangeably by people. Turtle is considered a reptile. It can be said that all tortoises are turtle but not all turtles can be characterized as tortoises. Turtle can be defined as the oldest reptile group residing on planet earth, they are even older than their reptile counterparts like snakes and crocodiles. The characteristic feature of the turtle tortoise duo is the presence of the shelled structure. The shell is made up of cartilage that arises from the ribs and covers the body. The main purpose of the shell is to act as a shield of defense for turtle and tortoise. This article focuses on the general understanding of the turtle reptile and tortoise, it also focuses on the habitat, classification, feeding habits, behaviour, and reproduction of the reptile.

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Classification of Turtle

Turtle is considered as a reptile, they are the oldest living reptile species that are found on the planet, they are even older than the snakes and crocodiles. The evolutionary study suggested that the earliest members of this group date back to the Middle Jurassic. Turtle and tortoise belong to the same order that is they belong to the order Testudines. The Testudines is alternatively named as Chelonia. They are the order that consists of the animals that have a true shell on the body. Although turtle and tortoise belong to the same order they belong to different genus and species. Both turtle tortoise duo is considered to be a reptile. 

The taxonomical classification of the turtle reptile is important to understand the position of the reptile in the natural ecosystem it also gives us a brief idea about the evolutionary history and relationship of the organism. Turtles belong to the taxonomical kingdom of Animalia, in the kingdom they are further classified into the phylum Chordata, which is characterized by the presence of the spinal cord. As mentioned above turtles are classified as reptiles, according to the taxonomical classification the turtles are classified under the class of reptilia, which is further classified into clade Perichelydia, this clade consists of the living or extinct organism (turtle tortoise and another relative organism) that dates back to Middle Jurassic to Holocene era in the geological time period. The clade is further classified into order. Turtle tortoise both belong to the order Testudines. There are various species of turtle classified under the order. Some of the examples of the turtle species include the Indian tent turtle and the Indian black turtle.

The taxonomical classification of the tortoise is similar to the turtles they also belong to the same order as turtles that order Testudines. This is also formerly known as the order Chelonia. Although the tortoise belongs to the same order they belong to different genus and species from turtle under the taxonomical classification. The order is further classified into suborder Cryptodira, they are then classified into superfamily Testudinoidea, which contains the family Testudinidae. Under this family, various species of the tortoise are classified. Example of such species includes Indian tortoise, red eared tortoise. The largest tortoise species is Galápagos tortoise.

Morphology and Features 

The distinctive feature of turtle morphology is the presence of the true shell. The shell covers the body and acts as a shield, the main function of the shield is to provide protection to the organism. The complete morphology and features f the organism both turtle tortoise can be defined on the basis of size, shell, head and neck, and also limbs description.

Size 

The size of the turtle is generally considered to be large. The largest turtle species the leatherback turtle can range up to the length of  2.7 m (8 ft 10 in) and the weight of the organism reach over 500 kg (1,100 lb). These species of turtles are considered as the fourth largest reptile species among the reptiles. There are also some species of turtle that are very small one of the examples of such species include the speckled padloper tortoise that is found in South Africa. They are considered smallest in turtle and tortoise they grow up to 8 cm (3.1 in) in length, and weighs about 140 g. The largest tortoise is the Galápagos tortoise. The Galápagos tortoise can range up to 1.87 m (6.1 ft) in length, and weights of over 417 kg (919 lb).

Shell

The shell is the outer protective covering of the body. The tortoise shells is made from the bones, they generally arise from the rib cartilage and extend to the body. The bones that form the shell of the body can be categorized into two groups, these groups are named as carapace and plastron. The carapace contains 50 to 60, the carapace bones cover the back of the organism. The plastron bone contains about 7 to 11 bones, the plastron bone is mainly responsible for the coverage of the belly of the organism.  The vertebrate of the turtle is fused with the carapace. The plastron of the organism forms the shoulder girdle, sternum, and dermal bones, gastralia, these bone structures are present to provide protection to the carapace. 

The shape of the tortoise shells varies in turtles and tortoise, the land dwelling turtles have a more pronounced doom shape of the shell. This shape ensures the protection of the organism from being crushed by other animals. The shape of the tortoise shell is flatter because they are generally found in the sea, the flat structure of the shell helps them to swim easily by cutting the water.  Shells of turtles and tortoise vary in their flexibility, the flexibility also changes from species to species in both turtle and tortoise. Recent studies also suggest that apart from providing physical protection and acting as a barrier the shell of both turtle and tortoise act as pH regulators. The shell helps in maintaining the pH of the body.

Head and Neck

The head and neck of the turtles lay outside the shell of the organism.  The mouth of the organism does not possess any teeth. Rather than teeth tortoise has a very strong bony cusp in the buccal cavity of the head. Also, it is interesting to note that the skull bones that make the head structure vary in shape and size among different species. Some of the skull bones are longitudinal in shape. Whereas some of the skulls of the species consist of flattened skull bone which is very broad in comparison to the skulls of the different species.  

The neck of the organism is very flexible. The flexibility is necessary to compensate for the rigid structure of the shell. The length of the neck varies from species to species. The neck of the turtle and tortoise contains 8 vertebrates. This number is consistent in both the organism. 

Habitat and Distribution

The turtles are widely distributed in the plant the only region where none of the turtle or tortoise is present is the polar regions. The turtle is found in aquatic terrestrial and pelagic environments that is they can inhabit a wide range of areas they can live in either of the mentioned habitats. Some of the species of the turtles are found in both land and water that is they live in the land for a specific period of time from their life span and then move to the ocean or sea. It is important to note that tortoise habitats are generally the aquatic ecosystem. Tortoise is generally found in the ocean or pelagic ecosystem whereas the turtles are generally considered to be terrestrial organisms. Depending upon the species the suitable environmental factor for the habitat can change, for example, turtles are generally not found in deep altitudes but some of the species of turtle like leatherback sea turtle can dive into the depth of  4,100 feet in the sea. Conversely, there are some species that reside in high altitude areas example of such species is  Terrapene ornata, this species is found in Mexico they live at a height of 6,600 feet. 

The major areas that have a huge population of turtle and tortoise include the following, the Amazon basin, the Southeastern United States, the coastal countries of tropical West Africa, Southeast Asia, Himalayan mountain ranges, the mountain ranges extending till Bengal. Some other regions that also have the species diversity in turtle and tortoise include Myanmar, Thailand Malay peninsula, Sumatra, the island of Borneo, Cambodia, Vietnam, and the southern coastal area of China.

Reproduction 

Since the turtle belongs to one of the evolved species that follow sexual reproduction, the mating behaviour varies from, species to species but one thing that is prominent in all the species is the lack of formation of mating pairs. As mentioned earlier the size is different among males and females of the species that is male of the species are generally larger in size than the females, this leads to rising of sexual dimorphism. Sexual dimorphism can be defined as the difference in size between the male and the female counterpart of the same species. It is generally seen that a male with a large body is preferred for mating. Thus it can be said that the largest tortoise mates with multiple females. Another important thing is the display of secondary sexual characters, the species where the males are not sufficiently larger than females for example in oceanic turtle species, the males display various aspects of dominance to gain mating access. The process of fertilization is an internal process, the female of the species then lays eggs.  

It is important to note that irrespective of species all the tortoise and turtle lay eggs. The eggs of all the species are laid on eggs. Although the turtle and tortoise are evolved they do not provide any parental care.  The mating among these organisms is recorded to be seasonal, they generally prefer mating during the spring and early rainy season. This can be explained as the parental care is minimal with these organisms, these seasons provide maximum feeding opportunities to the newly hatched young ones of the species. 

The life span of the turtles is very long, it is recorded that for some of the tortoise the lifespan can extend up to 176 years. It is also found that the adult male of the species shows about ninety nine percent of survival rate. 

Diet 

Most of the turtle and tortoise species are considered to be omnivorous. An omnivore can be defined as an organism that eats both plants and animals. It is generally seen that the terrestrial or land-dwelling species of turtle are herbivore dependent on plant leaves, and fruits. The ea or oceanic species of turtle are generally carnivores,  they generally feed on animals like mollusks, worms, and insect larvae. These are generally found in the sedimentary layer. These organisms are preferred because the turtle or tortoise does not have the agility and speed required to hunt other animals. Some species are exceptions to this generalization that is prey on various animals including small turtles and tortoise. Examples of such species include African helmeted turtle and snapping turtles both of these are land-dwelling species they considered as a dangerous turtle that prey on animals like amphibians, reptiles (including other turtles), birds, and mammals; they may take them by ambush but also scavenge. The turtle living in the aquatic ecosystem generally eats the marine grasses but in a case when these are not available, the diet of the organism changes from grass to algal growth in the water. These animals also sometimes eat bone remnants and the hair of other organisms to provide supplementary nutrition. 

Predators of Turtle and Tortoise

Turtle and tortoise have strong shells but they can be predated by mammals that are stronger than the turtle. The seawater turtles have predators that belong to the shark family. The predominant predator of the sea turtle is the tiger shark. Another key predator is the killer whales, the killer whales predate mostly the leatherback turtles. The young ones or the eggs of the species are generally eaten by the fishes, dogs, seabirds, raccoons, ghost crabs, and other predators. The larger mammals that live on the land can crush the tortoise shells of the land dwelling turtle and tortoise. The freshwater species of the turtle, as well as the tortoise, are hunted by crocodiles and alligators. 

Example of Indian tortoise

There are various species of Indian tortoise, it is recorded that about 28 species of tortoise and turtles are found in India,  some of the examples of Indian tortoise includes the following:

• Indian Tent Turtle

• Indian Black Turtle

• Leith’s Softshell Turtle

• Black Softshell Turtle

• African Helmeted Turtle and Snapping Turtles Are Considered Dangerous Turtle.

• Geochelone Elegans Is Also Known as Indian Star Tortoise.

• Red-Eared Tortoise Although Not Endemic to India Visit to Coastal Areas of India Like Chennai.

Difference Between Turtle and Tortoise

Although both of these organism groups are very similar share a large resemblance with each other, there are some differences that are listed below.

Conclusion

Both the turtle and tortoise are considered to be a reptile. The characteristic feature of this organism is the presence f the shell structure in the body, they are classified under the order Testudines. The size ranges from species to species the largest tortoise is the  Galápagos tortoise which can range up to 1.87 m (6.1 ft) in length and weighs over 417 kg (919 lb). The shell of the organism is made up of bones, which cover almost completely the body. The main purpose of the shell is to provide protection to the organism. They are found in both aquatic and terrestrial regions. They are also found in the freshwater ecosystem. The reproduction pattern can be defined as polygamous, that is male mates with many females. The sexual dimorphism is prominent in almost every species, the fertilization is internal. The organism lays the egg. It is interesting to note that they provide minimal to no parental care. Turtle and tortoise are considered omnivores but some of the species can strictly carnivores or herbivores. The carnivore predates on mollusks, worms, and insect larvae. Some of the examples of tortoise and turtle include Indian tent turtle, Indian black turtle, Leith’s softshell turtle, Black softshell turtle and, red eared tortoise, African helmeted turtle and snapping turtles are considered as the dangerous turtle.