Fascinating Facts
Physical Characteristics
Sea turtle shells (also called a carapace) are strong, light and streamlined and provide protection, buoyancy and the ability to slip through the water with minimum effort. The back or top shell is called the carapace and the bottom is called the plastron.
The shell is made of flattened bones covered in horny plates called scutes, with the exception of leatherback turtles that have a shell made from many small bones embedded in a leathery skin.
Scientists use sea turtle shells to identify different species. Scutes are bony external plates covered with keratin that cover the sea turtle's shell. They also use the number of pairs of scales on a sea turtle’s head to identify them, in addition to scutes. Each of the 7 species of sea turtle has a distinct carapace with a varying number of scutes.
Unlike most land turtles, sea turtles cannot retract their heads into their shell for safety. They have exchanged this feature for powerful fore (front) flipper muscles that propel them at great speed through the water. Their muscles take up so much room inside their shell that there is no room for their heads.
Sea turtles have strong, paddle-shaped fore flippers to power them through the water whilst the smaller rear flippers are used for steering and digging nest chambers. While slow and clumsy on land, leatherbacks can swim up to 35 km/h, making them the fastest reptile possibly in the world!
Sea turtles are world champions at holding their breath. Green sea turtles can hold their breath for as long as 5 hours. This is done by slowing their heart rate to nine minutes between beats to save oxygen.
One of the reasons sea turtles are fantastic swimmers is they have their own built in swim goggles. Sea turtles have nictitating membranes that protect their eyes from saltwater damage and improve their sight underwater, which is critical for spotting food items or possible predators.
The ‘tears’ often seen around a sea turtle’s eyes when it is on land come from special glands located near the tear ducts that excrete excess salt ingested while feeding underwater.
Sea turtles have no teeth. Instead, they have a beak with serrated edges that’s made of keratin. That’s right, the stuff our fingernails are out of! Their mouths have evolved to either shear food such as sponges and seagrass in the case of hawksbill and green turtles, or to crush food such as crustaceans and gastropods in the case of loggerheads and olive ridley turtles.
While sea turtles look cute and innocent on the outside, on the inside lies a terrifying (but harmless) sight. A sea turtle’s esophagus is lined with spiky papillae, which prevent prey like jellyfish from slipping out of their mouths while they expel seawater.
Sea turtles grow slowly and – depending on species – take between 11–40 years to reach sexual maturity.
Habitat
Although much is known of sea turtle’s activities when they come ashore to nest, little is known of their ocean activities. The young of most sea turtle species drift and feed in the open ocean until they reach about 5-10 years old and about 30 centimeters in length when they settle at inshore feeding grounds.
Sea turtles can live for years in one place, often returning to the same location to sleep. They make long migrations from feeding grounds to nesting beaches. The longest recorded (tracked by a satellite device attached to the turtles shell) migration was a tagged leatherback as it made a 20,558-kilometre (12,774-mile) journey from its nesting site in Papua, Indonesia to feeding grounds off the coast of the US state of Oregon. The journey took the turtle 647 days to complete!
The Green sea turtle is the only species of turtle that has a mostly herbivorous diet. As juveniles, they like to snack on small fish, crustaceans, and bugs. But as they grow, they switch over to a plant-based diet of seagrass and macroalgae.
Sea turtles are more likely than other animals to ingest plastic. They are also considered indicator species for plastic monitoring in the area due to their being long-lived and particularly susceptible to ingesting and getting entangled in plastic. Indicator species are used as a “snapshot” of the overall health and behavior of an ecosystem. Because plastic can accumulate in turtles over time, they give a good picture of what plastic pollution in their environment looks like.
Nesting
Females return to nest on the same beach, or beaches nearby, on which they hatched. How they achieve this remarkable feat of navigation is poorly understood, however, it is thought they use a combination of clues such as ‘reading’ the earth’s magnetic field and ocean currents and even judging the angle of the sun.
Most female sea turtles breed only every 2-3 years, as an annual breeding pattern would be too exhausting due to long migrations and the energy required to produce and lay many hundreds of eggs.
Female leatherback turtles can make some pretty weird noises. When they come up on shore to nest, they can make a noise that is comparable to a human belch.
Hatchling gender is dependent on sand temperature where the nest is located. Cooler sands produce are greater percentage of males, warmer sands produce more females.
Sea turtle embryos can pause their development. In a process called “preovipositional arrest”, eggs can sense that they are in a low oxygen environment while still inside the mother and pause their development until they are laid in a nest.
The male sea turtle doesn’t need to return to land to nest like female turtles. They spend their entire lives at sea.