About Sea Turtles

Species of Sea Turtles  |  About Turtles  |  Reproduction Cycle of Sea Turtles  |  Sea Turtle Navigation  |  More Sea Turtle Links

This graphic is provided courtesy of Peppermint Narwhal Creative.

Fun fact: a group of sea turtles is called a bale or flotilla. This graphic is provided courtesy of Peppermint Narwhal Creative.

Species of Sea Turtles

Kemps Ridley sea turtle Green Sea Turtle Loggerhead Sea Turtle
Hawksbill Sea Turtle

Common Threats to Sea Turtles


A Little Information on Turtles

Sea turtles are reptiles and a part of the Order Testudines which includes all turtles and tortoises. The most distinctive trait of this group is the protective shell. Like all reptiles, turtles have lungs and scaled skin. The shell is made up of two main parts: the ribs and backbone, and the dermal plates. The ribs and backbone are fused to the dermal plates on the top shell. The top shell is referred to as the carapace. The lower shell is called the plastron. These two bony parts are connected on the sides by cartilage. A layer of keratin (the same substance as your finger nails) covers both shells.

The only species of sea turtle without this type of shell is the leatherback. Their shell is cartilaginous (like your ears and nose). The shape and characteristics of the shell are variable between different members of the Order Testudines.

Sea turtles have a number of adaptations for life in the ocean. The shell of sea turtles is flattened to increase their ability to swim quickly. Their legs are elongated into paddle-like flippers. These two changes make it impossible for a sea turtle to “hide” or retract body parts inside their shell. Instead of hiding, speed and agility are used to out maneuver fast predators like sharks or whales.

Reproduction Cycle of a Sea Turtle

A female Kemp's ridley sea turtle buries her nest in 2012. Sea Turtle Inc. photo.

A female Kemp's ridley sea turtle buries her nest in 2012. Sea Turtle Inc. photo.

During the breeding season, male and female sea turtles come together and mate offshore. The males mount the females in the water and internally fertilize the eggs. Later, the female swims closer to shore and begins looking for a good place to nest. She walks ashore into the soft sand and excavates a body pit. Once this is complete, she begins to scoop sand with her rear flippers in an alternating fashion. The female digs a rounded, flask-shaped hole with a narrowing neck. The amount of eggs deposited in the nest depends on the species and size of the individual. On average, 50-180 leathery eggs are laid. The eggs incubate for 48 to 62 days depending on the beach temperature. The eggs are tightly packed and in contact with one another. Metabolic heating within the nest helps to speed up the hatching process in the final stages of incubation.

90 Kemp's ridley turtles fight their way to the ocean on the morning of July 8. The odds are tough for the Kemp's ridley. Only one to three in 1000 will live long enough to return to the Texas beaches to nest. Teresa Shumaker photo.

90 Kemp's ridley turtles fight their way to the ocean on the morning of July 8. The odds are tough for the Kemp's ridley. Only one to three in 1000 will live long enough to return to the Texas beaches to nest. Teresa Shumaker photo.

The hatching process occurs over a couple days. Once the hatchlings have absorbed their yolk sac, they crawl upward toward the warmer temperature of the surface of the sand. The sea turtle hatchlings usually emerge from their underground sandy nests under the cover of darkness. Then, when a majority of hatchlings are on the surface, they make a synchronized frenzied rush to the awaiting surf. As they scurry across the sand, predators including ghost crabs, vultures, seagulls, raccoons, coyotes and feral dogs predate many of the hatchlings. The hatchlings “imprint” on the beach as they walk out into the water. This refers to their ability to remember that specific beach and return to it as an adult sea turtle.

Once the baby turtles enter the water, they swim aggressively toward the origin of the waves, surfacing approximately every two minutes to breathe. Less than 1 percent of the hatchlings will survive their first year. Many animals in the water like crabs, fish, sharks and whales eat sea turtles. Regardless of the species of sea turtles, little is known where the young spend the first year of their lives, or "the lost year." Many biologists speculate that they float in and among rafts of sargassum weed, feeding on the rich variety of small creatures that seek refuge in it. Then, once the sea turtles reach maturity the cycle will begin anew. Depending on the species of sea turtle, it can take 15 to 30 years to reach maturity.

Sea Turtle Navigation

A Kemp's ridley hatchling follows the light of the rising sun to navigate to the ocean. Teresa Shumaker photo.

A Kemp's ridley hatchling follows the light of the rising sun to navigate to the ocean. Teresa Shumaker photo.

Scientists have demonstrated that hatchling turtles crawl toward the horizon and that they are able to detect subtle differences in light intensity. Artificial light sources from automobiles or street lights close to hatchling beaches tend to disorient the babies and many die as they crawl away from the ocean and onto roads and highways. According to biologists Salmon and Lohmann (1989), once in the water, the hatchling turtles orient toward the direction of the waves.

Dr. Kenneth J. Lohmann has recently made a strong case for the turtles having a built-in magnetic compass which enables them to orient themselves using earth's magnetic field to guide their long distance marine journeys. Placing newly hatched loggerhead sea turtles in a circular experimental tank, Dr. Lohmann mechanically reversed the magnetic field, causing the turtles to swim in the opposite direction. Dr. David Owens of Texas A&M University likewise has made a strong case for turtles responding to a particular water chemistry through their sense of smell (olfaction). Yet, other biologists believe that sea turtles utilize celestial cues, or "star maps." Perhaps a combination of these theories explains how sea turtles navigate.

Interesting Sea Turtle Links

Seaturtle.org has a wealth of information about sea turtles.

U.S. Fish & Wildlife Sea Turtle Brochure. Download the PDF.

The Anatomy of Sea Turtles by Jeanette Wyneken, PhD. View the book.

A selection of informative video clips are available at the NOAA website. View video page.