Sea Turtles Spend Their Entire Lives at Sea
Table of Contents
Sea turtles are marine reptiles that have evolved millions of years ago from terrestrial turtles and have developed numerous features that allow them to spend their entire lives in the water. Being reptiles that breathe with the help of lungs, turtles need to come to the surface to get air, but some species, such as the green turtle, are able to spend up to 5 hours underwater without surfacing and this is only one of the traits that allow them to live in the sea.
Sea turtles are widespread in all warm and temperate waters. They feed in the water, they sleep in the water, they mate in the water and they spend most of their time in the water, emerging on the surface only to breathe and climbing out of the water only to nest and to lay their eggs. Given the fact that sea turtles migrate over huge distances and they stay underwater almost all the time, very little is known about their behavior and they are, therefore, much studied by scientists.
Sea turtles live in salt water, and therefore one of the most important evolutionary features they have developed is the salt gland. This small organ is located in the orbital cavity of the animal and is there to remove the excess salt that the turtle ingests with its food and would be impossible to digest otherwise. The gland is of special importance for species that feed predominantly on jellyfish and plankton, such as the leatherback turtle. More than 90% of the jellyfish body is sea water that contains the same concentration of salt as the sea itself, and the species that feed on such prey rely on the salt gland to cope with the high salt concentration.
Sea turtles have developed flippers to enable more efficient swimming, and most of them have flexible carapaces that make it possible for them to endure the increased pressure in the deeper layers of water. The structure of their lungs also serves aquatic lifestyle: the lungs are very large and, upon resurfacing, the turtle is able to refill them with one quick and very strong breath; then, the animal returns under the surface.
Sea turtles come out of the water only for nesting. After mating in the sea, the females come to the shore to dig their nests and lay their eggs. Depending on the species they belong to, females lay 50-350 eggs into the hole they have previously dug into the soft sand close to the water. After laying the eggs, the females refill the hole with sand, some species even cover the nest with leaves or other vegetation for camouflaging, and then they return to the sea without waiting for their eggs to hatch. Incubation takes 50-60 days, then all the eggs in a nest hatch in a very short time and the young turtles start their first journey towards the sea.
Sea Turtles Spend Their Entire Lives at Sea: An Oceanic Odyssey
Sea turtles, those graceful mariners of the marine world, lead lives that are inextricably intertwined with the vastness of the ocean. From the moment they scramble towards the sea as hatchlings, to their final days as ancient voyagers, these creatures embody the essence of oceanic endurance and mystery. With their scientific classification falling under the superfamily Chelonioidea, sea turtles have roamed the world’s oceans for millions of years, adapting to life in a salty, fluid realm far removed from terrestrial constraints.
The Lifecycle Journey of Sea Turtles
Hatchling Hustle to Oceanic Odyssey
The journey of a sea turtle begins in a remarkable spectacle as hatchlings emerge from their sandy nests under the cover of darkness. This critical phase, often termed the “hatchling hustle,” is a perilous trek where these tiny creatures must evade numerous predators to reach the relative safety of the sea. Once in the water, they embark on what scientists call the “lost years,” a period where little is known about their whereabouts, as they drift and grow within the ocean’s vast pelagic zones.
Navigational Marvels of Mature Turtles
As they mature, sea turtles become navigational marvels, capable of migrating thousands of miles between feeding grounds and nesting sites. This incredible journey is guided by an innate sense, allowing them to use the Earth’s magnetic field as a compass, a phenomenon known as geomagnetic imprinting. Their migrations underscore the turtles’ deep connection to specific coastal areas, where females return to lay their eggs, often on the very beaches where they were born.
Unique Adaptations to Ocean Living
Physiological Mastery for Deep Dives
The oceanic lifestyle of sea turtles demands a suite of physiological adaptations that enable them to dive to impressive depths while foraging for food. Their ability to slow down their heart rate to conserve oxygen during deep dives is a testament to their evolutionary refinement. The leatherback turtle (Dermochelys coriacea), for example, can dive deeper than 1,000 meters, enduring the crushing pressures of the deep ocean to feast on its preferred prey, jellyfish.
Shell Evolution and Hydrodynamic Design
The evolution of the sea turtle’s shell reflects a masterclass in hydrodynamic design, allowing these creatures to glide effortlessly through their aquatic environment. Unlike their terrestrial relatives, sea turtles have a streamlined shell that minimizes drag and facilitates agile movement through the water. This adaptation is crucial for their long-distance migrations and evasive maneuvers to escape predators or navigate through treacherous reef systems.
The Role of Sea Turtles in Marine Ecosystems
Keystone Species in Oceanic Balance
Sea turtles play an indispensable role in maintaining the health and balance of marine ecosystems. As keystone species, their feeding habits help control the population of their prey, such as jellyfish and sea grasses, thereby preventing these populations from exploding and causing imbalances in the ecosystem. This ecological role extends to their nesting behavior, where the nutrients from unhatched eggs and hatchling remains provide vital nourishment to beach ecosystems.
Ingenious Contributors to Coral Reefs and Seagrass Beds
In their interactions with coral reefs and seagrass beds, sea turtles exhibit a remarkable symbiosis with their surroundings. Their grazing on seagrass beds is akin to a gardener tending to their lawn, promoting healthy seagrass growth and preventing the beds from becoming overgrown. Similarly, by feeding on sponges and other invertebrates in coral reefs, they play a critical role in maintaining the diversity and health of these vibrant underwater communities.
Conclusion
Sea turtles’ entire lives, spent roaming the vast expanses of the ocean, tell a story of resilience, adaptation, and ecological importance. Their journey from vulnerable hatchlings to majestic adults encapsulates the challenges and wonders of marine life. As sentinels of the ocean’s health, their survival and well-being are intricately linked to the conservation of marine habitats and the global commitment to sustainable ocean practices.
FAQs
What do sea turtles eat and how does it affect their habitat? Sea turtles have varied diets depending on the species. For instance, green turtles (Chelonia mydas) primarily eat seagrasses and algae, which helps maintain healthy seagrass beds. Leatherbacks consume large amounts of jellyfish, helping to keep jellyfish populations in check. Their feeding habits are essential in maintaining the balance of their respective ecosystems.
How do sea turtles navigate across the ocean? Sea turtles navigate the vast ocean through an extraordinary ability to detect the Earth’s magnetic field, a skill known as geomagnetic imprinting. This innate sense allows them to undertake long migrations across the ocean to feeding grounds and nesting sites, often returning to the exact beach where they were born to lay their eggs.
Why do sea turtles come ashore to lay their eggs? Sea turtles come ashore to lay their eggs because their ancestors were terrestrial reptiles, and this nesting behavior has been retained through millions of years of evolution. Laying eggs in the sand protects them from predators found in the ocean and ensures the right temperature and conditions for incubation.
How long do sea turtles live? Sea turtles are known for their long lifespans, often exceeding 50 years, with some individuals living up to 100 years or more. Their longevity, combined with their late maturity and low survival rate from hatchling to adult, makes their populations particularly vulnerable to threats.
What are the “lost years” in the life of a sea turtle? The “lost years” refer to the early period in a sea turtle’s life after it enters the ocean until it reappears in nearshore waters as a juvenile. During this time, which can last for several years, little is known about their whereabouts and behaviors. This period is crucial for their growth and development away from the predation pressures of coastal areas.
