tortoise es a terrestrial reptile belonging to the order Testudines They are characterized by having a shell that develops from their ribs and that helps them protect themselves against predators. This order includes all species, both living and extinct. The first known species date back 220 million years, being the oldest reptiles ahead of snakes or crocodiles.

Species

Currently 356 species of living turtles are known, of which some are in danger of extinction. The different species of turtles vary in size, color and diet.

Clade: Testudinata

  • Gender: Pappochelys

Disaster, tortoises

  • Suborder: Pleurodira
    • Superfamily: Cheloids
      • Family: Chelidae
    • Superfamily Pelomedusoides
      • Family: Pelomedusidae - Pelomedúsidos (Freshwater turtles)
      • Family: Podocnemididae - Madagascar Big-headed Tortoise and Podocnemis (River Turtles)

Clade: Polycryptodira

Clade Pantrionychia

  • Superfamily: Trionychoidea
    • Family: Carettochelyidae - Papuan loggerhead turtle
    • Family: Trionychidae - Trioniquids (Softshell Turtles)
  • Superfamily: Testudinoid
    • Family: Emydidae - Emydids and Terrapene.
    • Family: Geoemydidae - Geoemydids, Asian leaf turtle, quora and Batagur.
    • Family: Testudinidae - True turtles

Clade Americhelydia

  • Family: Chelydridae - Snapping turtle
  • Superfamily: Kinosternoidea
    • Family: Dermatemydidae - River turtles
    • Family: Kinosternidae - Eastern Marsh Turtle
  • Superfamily: Chelonioidea - Sea Turtles
    • Family: Cheloniidae - Herbivorous sea turtles
    • Family: Dermochelyidae - Leatherback turtle

Extinct tortoises

Giant tortoises of the genera Geochelone, Meiolania they existed in North and South America, Australia, and Africa. They became extinct at the same time that humans began to exist, who hunted them for food. The largest turtle in history was the sea turtle of the genus Archelon ischyros that lived in the Upper Cretaceous that was 4,6 m long.

The following families and genera of turtles are extinct:

Clade: Testudinata

  • Family: Proganochelyidae
  • Family: Australochelidae
  • Family: Proterochersidae

Clade: Mesochelydia

  • Family: Indochelyidae
  • Family: Heckerochelyidae

Clade: Perichelydia

  • Family: Chelycarapookidae
  • Family: Sichuanchelyidae
  • Family: Helochelydridae

Clade: Meiolaniformes

  • Family: Meiolaniidae
  • Family: Otwayemyidae
  • Family: Trapalcochelys
    • Gender: Chubutemys
    • Gender: Dangerchelys
    • Gender:Patagoniaemys
  • Family: Kallokibotiidae

Disaster, tortoises

  • Suborder: Pleurodira
    • Family: Apertotemporalidae
    • Family: Platychelyidae
    • Family: Dortokidae
    • Family: Notoemyidae
    • Superfamily: Pelomedusoides
      • Family: Araripemydidae
      • Family: Euraxemydidae
      • Family: Bothremydidae
  • Suborder: Cryptodira
    • Infrared: Paracryptodira
      • Family: Pleurosternidae
      • Family: Compsemyidae
      • Family: Baenidae
    • Infrared: Eucryptodira
      • Family: Macrobaenidae
      • Family: Eurysternidae
      • Family: Plesiochelyidae
      • Family: Xinjiangchelyidae

Disaster, tortoises

  • Suborder: Pleurodira
    • Family: Apertotemporalidae
    • Family: Platychelyidae
    • Family: Dortokidae
    • Family: Notoemyidae
    • Superfamily: Cheloids
      • Family: Chelidae
    • Superfamily: Pelomedusoides
      • Family: Araripemydidae
      • Family: FaEuraxemydidae
      • Family: Bothremydidae
  • Suborder: Cryptodira
    • Infrared: Paracryptodira
      • Family: Pleurosternidae
      • Family: Compsemyidae
      • Family: Baenidae
    • Infrared: Eucryptodira
      • Family: Macrobaenidae
      • Family: Eurysternidae
      • Family: Plesiochelyidae
      • Family: Xinjiangchelyidae

Clade: Centrocryptodira

  • Family: Osteopygidae
  • Family: Sinemydidae

Clade: Polycryptodira

Clade Pantrionychia

  • Family: Adocidae
  • Superfamily: Testudinoid
    • Family: Haichemydidae
    • Family: Lindholmemydidae
    • Family: Sinochelyidae

Clade Americhelydia

  • Superfamily: Chelonioidea
    • Family: Toxochelyidae
    • Family: Thalassemydidae
    • Family: Protostegidae

Features

The tortoise is classified as amniotes, along with other reptiles, birds, and mammals. Like other amniotic animals, they breathe air and do not lay their eggs under water, although many of them live most of their life in it. The life expectancy of a tortoise is very similar to that of humans, although some species far exceed humans, such as the giant tortoise that can live for more than 150 years.

They are ectothermic animals (cold-blooded animals) so the internal temperature of their body varies according to the environment where they are. However, sea turtles due to their metabolic system have a higher body temperature than that of the water around them.

Sea turtle

Sea turtle

Head

The vast majority of tortoises that spend their lives on land have downward-facing eyes. Aquatic birds have their eyes closer to the top of their heads. These species of turtles hide in shallow water to hide from predators but do not completely submerge their bodies, since they must leave their eyes and nostrils outside the water. Sea turtles, living all their lives in the sea, must drink salt water, so to expel the salt they have glands that generate salty tears that release the excesses.

They have a stiff beak at the top of their heads and you use jaws to cut and chew food. Apparently they lost their teeth 150-200 million years ago, so instead of teeth the jaws are covered by horny grooves. In carnivores the grooves are usually sharp like knives to cut their prey. Herbivores have grooves with serrated edges to cut the toughest plants. With their tongues they swallow food, however, they cannot stick their tongues out to catch their prey like other reptiles do.

Size

The largest turtle is the leatherback turtle (Dermochelys coriacea), a marine animal that reaches a length of about 20 m and can weigh about 900 kg. Those that inhabit fresh water are smaller species but there are always exceptions, such as the Cantor's tortoise (Pelochelys cantorii) a strange species of turtle that does not have a shell, in which specimens of up to 20 m have been found. This dwarfs the known alligator turtles (Macrochelys temminckii), the largest tortoise in North America, which can reach 8 m in length and weigh 112,4 kg.

Of the only currently surviving giant tortoises found on the Seychelles and Galapagos islands, they can measure more than 13 m and weigh 300 g. The smallest in the world are spotted turtles o Cape spotted turtles (Crocodylia sealed;) measuring 8 cm and weighing 140 g. Other species of small turtles are the eastern marsh turtle or common marsh turtle (Kinosternon subrubrum) and the common musk turtle (Sternotherus smell) that inhabit from Canada to South America.

Retractable movement

They are divided into two groups according to how they retract the neck into their shell (something that the ancient late Triassic tortoises could not do). The neck is retracted laterally to the side, anterior to the shoulder girdles in the Pleurodira suborder. And it retracts straight back, between the shoulder girdles, in the genus Cryptodira. These movements can be carried out thanks to its morphology and arrangement of the cervical vertebrae.

In recent tortoises, the spinal column is made up of nine joints and eight individually independent vertebrae. Since these vertebrae are not fused and are rounded, it allows you to easily move your neck back and to the sides. This movement is believed to have evolved to prioritize food, rather than protection. Thanks to the retraction and extraction of the neck, they can go further to capture their prey while swimming.

The protection that the shell provides to the turtle is not the main function for which the retraction was "intended", however, it was later perfected to give it a different use, this is called exaptation.

Shell

Turtles are known for their shells, but only the upper part (the one that is visible and hard) is called that. The lower part that covers the belly is called the plastron and it is a much softer part than the upper part. The two are linked by bony structures called bridges. It is trapped in its shell, as the inner layer is made up of about 60 bones that include parts of the spine and ribs.

In most species, the carapace is covered with horny scales that are part of the outer skin. They are made of fibrous keratin protein that other reptiles also possess. The scales help give the shell strength. Some turtles do not have horny escapes, such as the laud turtle (Dermochelys coriacea) or as turtles belonging to the family Trionychidae called softshell turtles, which are covered in leather skin.

The function of the outer shell is to protect itself from predators. However, it does not cover the entire body so both the head, legs and bellies are unprotected and are quite soft and soft. To protect the unprotected parts, the turtle is able to retract its limbs into the shell. The carapace varies in size depending on the type of turtle and species, measuring a few centimeters to a couple of meters.

Tortoise shell from above

Tortoise shell from above

The shape of the shell determines how a turtle lives. Turtles have a large dome-shaped shell that makes it difficult for predators to crush the shell with their jaws. There are also exceptions like la rock turtle or pancake turtle (Malacochersus tornieri) that has a flexible shell that allows it to access rock crevices. In aquatic turtles it has flat and aerodynamic shells that help it to swim and dive. Other turtles, such as alligator turtle (Macrochelys temminckii) o common musk turtle (Sternotherus smell) They have a cross-shaped plastron that provides them with more efficient movement to be able to walk better on the bottom of lakes and streams.

The color of the carapace varies by species. They are usually brown, black, or olive green. In certain species, they may have red, orange and yellow or gray markings or irregular spots, lines or spots. The most colorful turtle is the eastern painted turtle, which has a yellow plastron and a black or olive shell with red markings on the edges.

In land turtles the shell is very heavy compared to aquatic turtles which have a soft and light shell to avoid sinking and swimming faster. Lighter shells have large spaces between the bones of the shell called fontanelles. In the shell of the leatherback turtle (Dermochelys coriacea) lack scales and contain many fontanelles which makes them very light in water.

Breathing

For amniotics, breathing is achieved through the contraction and relaxation of specific muscle groups made up of intercostals, abdominal muscles or diaphragm that are attached to the internal rib cage that expands or contracts helping the lungs in the flow of air. However, in chelonians the carapace is fused with the ribs and they are external to their pelvic and pectoral girdles, a unique characteristic of turtles. That is why they have developed special adaptations to be able to breathe.

Pulmonary respiration in turtles is carried out using certain groups of abdominal muscles that are attached to the viscera and shell that push out of the lungs in a ventricular manner during inspiration, where the air is exhaled through a negative pressure gradient ( Boyle's Law). On expiration, the contraction of the transversus abdominis is the driving force that pushes the viscera into the lungs and expels air under positive pressure.

In contrast, relaxation and flattening of the abdominal oblique muscle pulls back the transversus, which, once again, returns air to the lungs. This process is accompanied by the auxiliary muscles are the pectoralis, which is used together with the transversus abdominis in inspiration, and the serratus, which moves with the oblique abdominal that accompanies expiration.

River turtle breathing

River turtle breathing

The lungs of the testudins are multi-chambered and connected across the shell. The number of chambers varies among taxa, although they commonly have three lateral chambers, three medial chambers, and a terminal chamber. As we've said before, the act of specific abdominal muscles lowering the viscera (or pushing up) is what allows turtles to breathe.

The large size of the liver of the turtles which pulls or pushes the lungs. In the coelomic cavity, the liver of turtles is attached directly to the right lung, and their stomach to their left lung by the ventral mesopneumonium, which is attached to the liver by the ventral mesentery. When the liver is knocked down, inspiration begins. The support of the lungs is the postpulmonary septum, which is found in all testudins, and is believed to prevent the lungs from collapsing.

Water breathing

All turtles breathe air, so aquatic ones need to come to the surface at regular intervals of about 8 hours on average, to fill their lungs with oxygen. Some species have large cloacal cavities that are lined with many finger-like projections. These projections, known as papillae, have a rich blood supply and increase the surface area of ​​the cloaca. They can absorb dissolved oxygen from the water using these papillae, in the same way that fish use gills to breathe.

Skin and molt

The outer layer of the carapace is part of the skin and each groove corresponds to a single modified scale. The rest of the skin has very small scales, very similar to those of other reptiles. They do not shed their skin all at once like snakes do, but constantly shed it in small pieces. When kept in aquariums, small sheets of dead skin can be visualized in the water (which can look like a piece of plastic) that comes off when they have been detached when animals rub against other objects. They also lose skin, but dead skin accumulates in thick knobs and plates that protect parts of the body outside the shell.

It is possible to determine the age of a turtle by counting the rings that form in the pile of the smallest and oldest scales on the largest and newest. To do this correctly, you must know the number of scales that occur in a year in that species in which you want to determine the age. However, the method is not very precise, since the growth rate of the scales is not constant and because some scales may detach from the shell.

Ends

Land tortoises are known for their slow movements. Their legs are short and sturdy, restricting the length of the stride. The shell is heavy and cumbersome. All of these factors affect your movements.

Aquatic turtles have limbs that are very similar to those of tortoises, but the feet are webbed, and in certain species they have claws. These types of turtles swim in a "puppy" shape, moving their legs slightly with the difference that they alternate the thrust between the left and right legs. The larger the turtles, the less they swim and prefer to walk along the bottom of the river or lake, like the alligator turtle (Macrochelys temminckii). When they have claws, they are very long and are used to easily get out of rivers and to climb floating logs, to sunbathe. Males have larger claws than females, which are used to stimulate the female during mating. Some turtles, such as tortoise boba papuana (Carettochelys insculpta) have true fins, with the fingers fused in the shape of paddles and the claws being relatively small. These species swim in the same way as sea turtles.

Sea turtles spend most of their lives in the sea, therefore they have fins instead of legs. These flow through the water in an up and down motion with the front fins to generate thrust. The hind legs are used as a rudder. Compared to freshwater turtles, they have very limited mobility on land. Besides the race from the nest to the sea as hatchlings, the males never leave the sea. However, the females must return to the ground to lay their eggs, where they move very slowly and awkwardly, pushing themselves forward with their flippers.

Behavior

Senses

Turtles are considered to have exceptional night vision thanks to the unusually high number of rod cells in their retinas. They have the ability to see in color with a large number of cone subtypes ranging from near ultraviolet (UVA) to red. In tortoises, the pursuit movement capacity is very low, since it is usually needed more in animals that hunt extremely fast moving prey. Although carnivorous tortoises are able to move their heads quickly to split their prey in two.

Communication

Normally we think that turtles are mute and do not make sounds, but it is a totally wrong approach. Turtles are capable of making various sounds to communicate. The most famous are those issued when they court or mate. Many aquatic species emit low-frequency sounds, invaluable to humans, from the time they are in the egg until they are adults. These vocalizations are used to communicate when migrating in groups.

Financial

There are reports that determine that the forest terrapin tortoise (Chelydridae imprinted) is much more efficient at solving mazes than white mice. There are also case studies where turtles have lived together playing with each other. However, the scephalisation quotient is really low in relation to their body mass and their hard shells allow them to live without fast reflexes and without the need to elaborate great strategies to flee from predators.

In the laboratory the turtles (Pseudemys nelsoni) have been shown to be able to store information and learn new operational tasks within 7,5 months.

Habitat

The turtle prefers the environment to be humid and open. The adaptability of turtles is very varied, managing to survive in various environments.

  • Turtles: They prefer forests, deserts and tropical jungles, although in their surroundings there must be water to be able to drink and keep their body constantly hydrated. When winter comes, many species decide to hibernate.
  • Aquatic turtles: They are present in rivers and lakes.
  • Sea turtles: It is perfectly adapted to the sea and only the female must go ashore to lay eggs, preferring ocean basins and tropical beaches.

Distribution

Turtles are found throughout the planet. The marinas are concentrated in the ocean currents of Japan and California. They are also distributed from the Chilean coasts to Alaska. Tortoises are concentrated in Europe and Africa. The giant tortoises that remain alive live only on the Seychelles and Galapagos Islands.

Food

The turtle varies its diet depending on where it lives. Adult turtles feed on aquatic plants, invertebrates such as insects, snails, and worms, and have been reported to occasionally prey on dead marine animals. Some small freshwater species are carnivorous, feeding on a wide variety of aquatic species. When they are young they need protein to grow so they are all purely carnivorous.

Sea turtles consume jellyfish, sponges, and other soft-bodied animals. Some species with stronger jaws eat shellfish, while others, such as the green turtle (Chelonia mydas) is strictly herbivorous with a diet composed of algae.

Predators

The turtle has certain natural predators according to the habitat where they live and the species. Generally, tortoises have as predators dogs, wild cats, crocodiles and wolves. Other animals some birds, mammals and even reptiles feed on the eggs. Sea turtles are victims of dolphins, sharks and killer whales.

Humans are also a predator of turtles, especially in indigenous populations and parts of Asia. Meat is considered an aphrodisiac delicacy, unfortunately it is an erroneous belief and with its shell objects and artisan tools are made. Certain species are also caught to be sold as pets.

Reproduction

It takes many years for turtles to reach reproductive age, and in some cases, they reproduce every several years instead of once a year.

As in many reptiles, turtles lay soft, white eggs. The eggs are spherical in the largest species, while those of the rest of the species are elongated. In some species, temperature is key to determining the gender of the young. If the temperature is high, it will cause a female. If it is low it will cause a male. Unlike bird eggs, turtle eggs do not coagulate as they are made up of a different protein. Ready-to-eat eggs consist of yolk only.

The eggs are deposited in large quantities in holes dug in mud or sand, which are then covered and incubated by themselves. The eggs hatch in about 70-120 days, depending on the species. When the hatchlings hatch, they must dig to surface and head towards the sea or to a safe area in the case of terrestrial ones. This stage is crucial, as many will be hunted by predators.

State of conservation

The conservation status of turtles is highly variable depending on whether they are terrestrial, marine or aquatic (freshwater). In February 2011, the Tortoise and Freshwater Turtle Specialist Group published a report on the 25 species of turtles most likely to become extinct, along with 40 other highly endangered species. of extinction. Sea turtles are excluded from the list, but both the leatherback turtle (Dermochelys coriacea) as the olive ridley turtle (Lepidochelys kempii) would be among the top 25.

Between 48 - 54% of the species are considered threatened, a higher percentage if we compare it with other species of vertebrates. Of the 263 species of freshwater and terrestrial aquatic turtles, 117 are considered threatened, 73 are in danger of extinction and one of them is currently extinct. Being the Testudinidae family the most affected with 33 threatened species of the 58 species that make up the family. 70% of all species are extinct or in danger of extinction. Asian species are the most affected, closely followed by the five endemic species of Madagascar.

Turtles face numerous threats such as habitat destruction, collection for consumption, and the pet trade. The high risk of extinction for Asian species is mainly due to long-term unsustainable exploitation of turtles for consumption and traditional Chinese medicine, and to a lesser extent for the international pet trade.

Land turtle

Land turtle

Relationship with humans

Humans have been related to turtles in various ways throughout history. They are currently kept as pets or used as food, traditional medicine and cosmetics.

As pets

Humans keep certain species as pets. The favorites are the small tortoises and fresh water like the russian tortoise (Testudo horsfieldii), The African spurred tortoise (Centrochelys sulcata) And painted turtle, elusive turtle or jicotea (Trachemys scripta).

As a curiosity, in the United States the United States Food and Drug Administration (FDA) has not allowed the sale of turtles under 4 years of age (100 mm) since 1975. The reason is because salmonlosis can be easily contracted through of casual contact. However, they are still sold in some markets, because the FDA law contains a loophole that allows them to sell them if it is for educational purposes.

I eat food

The meat of some turtles are considered a delicacy in certain parts of the world. Turtle soup is highly regarded in Anglo-American cuisine and also in certain parts of Asia. Gopher tortoise stew was popular in Florida.

On the island of Grand Cayman, turtles are still eaten and are a highly valued food of the traditional diet to the point of depleting wild populations. But they did not stop there, some farms were established to create sea turtles and thus be able to consume their meat. However, not everything is negative, as the farm releases specimens to the Caribbean Sea in order to reprove it again.

Cosmetics

In the Caribbean and in Mexico, turtle fat is still used as the main ingredient in foodstuffs that are traded under the name "Tortoise Cream."

Traditional medicine

Plastrons are widely used in traditional Chinese medicine. Hundreds of tons of plastrons are imported into Taiwan each year. With the plastrons, the guilinggao jelly is prepared, mixing it with a variety of herbs. Currently, it is only prepared with herbal ingredients.

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