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Sea Turtle

  Sea Turtle: The Ancient Navigator



Marine turtles serve as vital bio-indicators for the world's ocean environment, playing a crucial role in preserving our marine life. These magnificent reptiles are not only ancient but also a distinctive component of marine biodiversity, having evolved over 150 million years ago. Originating from giant land turtle ancestors who transitioned to sea life during the age of dinosaurs, marine turtles have since roamed the world's oceans. There are seven recognized living species of sea turtles across six genera, including Olive Ridley (Lepidochelys olivacea), Green turtle (Chelonia mydas), Loggerhead (Caretta caretta), Leatherback (Dermochelys coriacea), Hawksbill (Eretmochelys imbricata), Kemp's Ridley (Lepidochelys kempii), and Flatback (Natator depressa). Each sea turtle species possesses unique characteristics. Regrettably, all species, with the exception of the Australian Flatback, are listed as either threatened or endangered.

Sea turtles face a multitude of perils as they traverse the oceans. These threats include entanglement in fishing gear intended for other species, loss of nesting and feeding habitats, direct hunting, and pollution.

Here are some key facts about marine turtles:


Adaptations to the Marine Environment: Marine turtles are air-breathing reptiles perfectly adapted to their oceanic habitat. Their size varies significantly among species, from the small Kemp's Ridley, weighing 80-100 pounds, to the colossal Leatherback, which can exceed 1,000 pounds.

Exceptional Navigators: These ancient creatures are remarkable navigators, capable of recognizing their own nesting beaches even after many years. Female turtles return to their birthplace to lay eggs. Scientists believe that they use Earth's magnetic field for navigation. During their travels, they transport vital nutrients and enhance the productivity of coastal underwater vegetation. Sea turtles are prodigious travelers, covering distances as great as 12,000 kilometers to reach their nesting grounds. Unlike many higher animals, sea turtles can perceive color.

Longevity and Reproduction: Marine turtles are long-lived, with maturity achieved between 15 to 50 years. They undertake extensive migrations, moving across oceans for nesting, foraging, and mating. Although the exact lifespan of sea turtles is still under investigation, once they reach sexual maturity, some species may reproduce for up to 30 years.

Diet: Different species of marine turtles have distinct dietary preferences, with specialized mouths and jaws to help them consume their preferred prey. They inhabit distinct areas for eating, resting, mating, and swimming.

Life and Reproduction: Despite their oceanic lifestyle, sea turtles must return to the shore to breathe and lay eggs on tropical sandy beaches. They spend their entire lives at sea, with female turtles coming ashore to lay eggs multiple times each season, every 2-5 years. After a nesting event, eggs are buried in 50-100 cm deep egg chambers and incubate in the natural heat of the sun for 50-65 days. These strong swimmers can reach speeds of over 50 kilometers per hour.

Ocean Life: Once sea turtle mothers lay their eggs on the beach, they have no further responsibility for their offspring. Hatchlings find their way to the sea at night, guided by the brightest horizon. The sex of marine turtle hatchlings depends on the incubation temperature. In their early years, they roam the open ocean before moving to protected bays, estuaries, and other nearshore waters. Male sea turtles rarely leave the ocean, aside from occasional visits to remote, uninhabited beaches. During nesting, female sea turtles search for safe sandy beaches and, if undisturbed, leave the water to nest.

It is disheartening to note that marine turtle populations worldwide have significantly declined due to various human influences. Overdevelopment of coastal areas has resulted in the loss of natural nesting habitats. The capture of adult turtles for their eggs, meat, leather, and tortoiseshell has significantly diminished breeding populations. Incidental capture of adults in fishing nets and shrimp trawls has pushed the Kemp's Ridley turtle to the brink of extinction. As a result, all species of sea turtles are internationally protected.

In Bangladesh, marine turtles are protected by the law under the revised Bangladesh Wildlife (Preservation) Act of 2005. This law prohibits any harm or harassment to marine turtles, their nests, or eggs. Violations of the law can result in civil penalties or imprisonment.

However, despite these protective measures, marine turtles in Bangladesh face numerous threats and challenges. Illegal egg collection, loss of nesting grounds due to developmental activities, predation of sea turtles, eggs, and nests, turtle mortality in the sea due to bycatch, the impact of tourism, and the issue of lighting along the coast are just a few of the concerns. These challenges have led to a significant reduction in the sea turtle nesting population.

Despite these challenges, marine turtles play a vital role in the health of our oceans. By saving sea turtles, we can also help preserve our oceans. Sea turtles are considered keystone species, and their presence indicates the overall health of the marine ecosystem. Marine turtles help regulate the marine environment, and the loss of these species can lead to the collapse of entire ecosystems.

You can make a difference in marine turtle conservation by following these recommendations:

  • Refrain from littering to protect sea turtles from harm.
  • Encourage fishermen to use Turtle Excluder Devices (TEDs) to reduce turtle mortality.
  • Avoid walking on the beach at night during the sea turtle nesting season.
  • Never keep sea turtles in captivity.
  • Minimize bright lighting along the beach to prevent disorientation of hatchlings.
  • Report stranded, injured, or healthy sea turtles to the appropriate authorities.
  • Educate others about the importance of sea turtle conservation.
  • Support organizations and initiatives working to protect marine turtles.

By taking these steps and spreading awareness, we can contribute to the survival of these magnificent creatures and the preservation of our oceans.

 

 




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