Fascinating Facts on the Sea turtles

…are a part of the animal group called reptiles

Reptiles (lat. reptilis – the one that crawls) are a class of vertebrates, which is the first in the course of evolution fully emerged on the mainland thanks to the development of the amniotic egg. These are cold-blooded – poikilotherm organisms, which means that their life cycle dependent on the ambient temperature. Sea turtles certainly spend a lifetime in the sea, why they have developed a series of adaptations which facilitate the movement of water. The main alterations are hydrodynamic shell and limbs that are transformed into the flippers. The front flippers are used for swimming, while the rear flippers have the function of rudder and serve to guide the body as well as for the excavation and backfilling of nest by females. Sea turtles live on average 60-70 years. They are slow growing species which become sexually mature around 20 years of age.

…are distributed mainly through tropical and subtropical seas

Due to the fact that they are cold-blooded organisms and their body temperature depends on the ambient temperature, sea turtles live mainly in warm seas. Only leatherback turtles, due to its size, inhabits the colder seas, located at higher latitudes.

…counts in total seven species trough world ocean. In the Adriatic Sea exist three sea turtle species – loggerhead turtle, green turtle, and leatherback turtle

All sea turtles belong to the superfamily called Chelonioidea. There exist in total seven species of sea turtles: the loggerhead turtle – Caretta caretta, the green turtle – Chelonia mydas, the hawksbill turtle – Eretmochelys imbricata, the flatback turtle – Natator depressus, the Kemp’s ridley turtle – Lepidochelys kempii, the olive ridley turtle – Lepidochelys olivacea and the leatherback turtle – Dermochelys coriacea. The most common species in the Adriatic Sea as well as in the whole Mediterranean Sea is the loggerhead turtle. In addition to loggerhead sea turtles, in the Adriatic Sea also the green and leatherback turtle are present, but the number of individuals of these two species is small.

…have hard shell made of skeletal plates. The leatherback turtle does not have a shell-like this, shell in this species is actually made of skin, based on which the species is named

The distinctive feature of all turtles on planet Earth is their shell. The shell has primarily a protective function. The shell is made of strong making strong skeletal components and scutes. Sea turtles have a different number of scutes, which allows their identification. The shell is composed of two parts: the carapace and plastron which are connected with skeletal bridges. Carapace, the dorsal part of the shell, is convex and is composed of five types of scutes: vertebral, costal, marginal, cervical and suprapygal. Plastron, the stomach part of the shell consists of six scute pairs: gular, humeral, pectoral, abdominal, femoral and anal. Sea turtles do not have the ability to drawn their neck, head and flippers into the shell as other land and freshwater turtles. The leatherback turtle is the only sea turtle which is lack of a bony shell. The shell is covered by thick leathery skin instead of horny plates. Along the upper shell are very prominent ridges, usually five or seven and four below.

…breath by lungs, why they have to go out on the surface to take a breath

The sea tutles life cycle is related to water. Since the lungs breath, occasionally come to the surface to take air. Athere exist two main “periods”, period of intensive ventilation – breathing, occurs when the turtle is on the water surface and period of breath holding, when turtle is under water. When resting or sleeping, se turtles can carry up under water up to 7 hours. The leatherback turtle can dive to great depths, up to 1200 m, and this is all thanks to a series of adaptations such as the presence of oil in the skin and the shell ability  to absorb nitrogen and thus prevent problems with decompression occurring at such great depths.

… are a part of the animal group which has a complex life cycle including the longest migrations due to mating. Some species crossing up to 6000 km in order to come to nesting beaches

The sea turtles life cycle starts ith laying eggs. Females lay eggs at night, and always return on the beaches where they were hatched themselves. This phenomenon is called philopatry. Depending on the species, the number of eggs in the nest ranges from 50-130, and incubation of eggs lasts from 50-80 days. In sea turtles “temperature-dependent sex determination” is present, gender depend on nest temperature. Ii is found that in loggerhead turtle females hatch when the nest temperature is higher than 29°C, otherwise males hatch. Young turtles hatch from eggs during the night to avoid predators, and with the help of moon and stars reflection on the sea surface they orient and move towards the sea. Then stasts period of life that is called pelagic period. During this period the young turtles intensively feed and grow. This period of life takes 10-15 years and it is a great mystery to scientists. After this period, the sea turtles make their way to coastal waters, where they mature, become sexually mature and remain there for life. This period of their life is called neritic period. In the breeding season, sea turtles migrate and travel long distances to the coast where they mate and lay eggs. The loggerhead turtles that inhabit the north Adriatic Sea migrate to the coasts of Greece where the mate and lay eggs after what return to the waters of north Adriatic. It is nteresting that the males during life never come ashore. It consists of females, and only when the eggs are laid. As youngs, sea turtles have many natural enemies, of 1000 juveniles only one survives.

…depending on the species, can reach weight up to 1 tone, while shell length can be even up to 3 m

The largest species of sea turtles today is the leatherback turtle. Length of the shell in this species is typically less than 2 m, but there have been few examples of 3 m shell length. The leatherback turtle is also one of the biggest, some individuals may weigh more than 900 kg. Other species are smaller, the length of their shell, depending on the species, ranges from 70 to 150 cm, and body weight typically ranges from 100-150 kg. Rare specimens of green turtle may reach a body weight up to 400 kg.

…are carnivorous species. Often eat plastic bags because they look like jellyfish on which sea turtles feed on

Sea turtles do not have teeth. They have a sharp beak-like mouth, which crushed sturdy prey such as shellfish and crustaceans. All species are carnivorous and feed on crabs, clams, sea urchins, sponges, jellyfish. The exception is the green turtle, which is a herbivore and feeds on seaweed.

…are endangered mainly due to negative anthropogenic factors and activities on the coast and the sea – coast destruction, fishing, maritime transport, sea pollution

As adults sea turtles have very few natural enemies. However, the greatest enemy of sea turtles are humans and they activities on the coast and the sea as: tourism development, intense urbanization and the expansion of cities, fishing, maritime transport, sea pollution One of the biggest threats to sea turtles in the Adriatic Sea is fishing. It is estimated that annually bycatch in the Adriatic Sea by bottom trawls is about 5,000 individuals. Usually these individuals are hibernation and proper handling by fishermen, can safe their life. Nets are much bigger problem, because almost all the turtles bycatch in nets die due to suffocation, because these nets stay in a water for a longer time. Longlines are also problem, because sea turtles frequently swallow prey from longlines, as well as hooks that damage their digestive system and often leads to death. Marine litter, especially plastic is a major threat to sea turtles. Sea turtles swallow plastic and other waste because it reminds them to their natural prey. Sea turtles often swallow plastic bags which looks like jellyfish, what unfortunately, in most cases, results in their mortalities. Tourism development, as well as population growth, led to the urbanization of coastal areas and destruction of sandy beaches where sea turtles lay eggs. Light and noise on the coast can fear females during laying eggs, and also affect the disorientation in juveniles after their hatchling and their “trip” to the sea.

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