English Documentary on Sea Turtles with Transcript & Flashcards

English Documentary on Sea Turtles with Transcript & Flashcards to perfect your English and expand your vocabulary. You can also watch the video podcast and ready the corresponding transcript

Source of documentary: National Geographic YouTube Channel

Source of image: https://www.nbcnews.com/

Listening comprehension

Reading comprehension

Sea turtles

Sea turtles are ancient mariners. Present in all but Earth’s coldest oceans, these marine reptiles are well-adapted to a life on the move.

Sea turtles’ ancestors

Sea turtles have existed since the time of the dinosaurs. The earliest known marine turtle lived about 120 million years ago. Named Desmatochelys Padillai, it was six feet long and had the characteristic features of modern sea turtles, including a carapace or top shell and paddle-like limbs.

Today, there are seven species of sea turtles with the largest being the leatherback growing as long as eight feet and weighing up to 2,000 pounds, it is larger than known fossils of its prehistoric ancestor, the Padillai.

Reproduction

Sea turtles can lay more than 150 eggs at a time. Called the clutch, these large egg deposits help ensure the survival of the sea turtle hatchlings. Once a female lays her eggs, she returns to the sea, leaving her hatchlings to fend for themselves.

Fewer than 0.1% of hatchlings survive to adulthood in part due to numerous predators on the beach. Emerging in large numbers increases the chance that some will survive.

Gender

A sea turtle sex is determined by temperature. Unlike most vertebrates, a sea turtle sex is not determined by sex chromosomes; instead, the temperature of the nest determines the sex of the hatchlings. When temperatures are warm at about 88 degrees Fahrenheit, most of the hatchlings will be female, but when temperatures are cooler, less than around 82 degrees Fahrenheit, most of the hatchlings will be male.

Navigation

Sea turtles use Earth’s magnetic fields to navigate. Sea turtles have geomagnetic abilities, which serve as an internal GPS. The turtles have particles of magnetite, a magnetic mineral in their brains. The magnetite likely plays a role to orienting sea turtles to Earth’s magnetic poles, similar to a compass.

Baby sea turtles imprint on the unique magnetic signature of the beaches where they hatch. This magnetic map can guide them back to the same beaches several years later to lay their own eggs.

Vulnerable creatures

All seven sea turtle species are threatened with extinction. Once abundant, sea turtle populations have dramatically declined in the past two centuries. Fishing is a major threat to sea turtles. As they become caught in the fishing nets as bycatch or accidental catch, illegal harvesting of turtle eggs, trafficking internal products, and ocean pollutions are also concerns.

However, policies have been enacted to reduce bycatch, protect turtle habitats, and prohibit the killing of sea turtles and their eggs.

By continuing this kind of intervention, humans can help stop the decline of sea turtles, helping keep these ancient mariners in the world’s oceans.