Do Sea Turtles Hold The Key To Immortality?

Sea turtles are ancient creatures that have inhabited the Earth's oceans for over 100 million years. With seven distinct species, these marine reptiles are known for their long lifespans, which can range from 50 to 100 years or more. While it is challenging to determine the exact age of any sea turtle species, their longevity is comparable to that of humans. Sea turtles take decades to mature, typically between 20 to 30 years, and remain reproductively active for about another decade. Despite facing various natural predators and human-induced threats, sea turtles have evolved to live extended lives in their natural habitats.

Human impact on sea turtle lifespan

Sea turtles have been roaming the Earth's oceans for 110 million years, but their populations are on the decline due to human activities. While it is challenging to accurately determine their lifespan, estimates suggest that some species of sea turtles can live up to 50 years or more, with similarities to human lifespans. The impact of human activities on their lifespan is significant and multifaceted.

One of the most detrimental human impacts on sea turtle lifespan is accidental capture by fishing gear. Thousands of sea turtles are entangled and drowned in commercial fishing nets, such as shrimp nets and gill nets, each year. This issue is particularly severe because sea turtles need to surface to breathe and cannot survive underwater for extended periods. Longline fisheries, with their miles-long lines and thousands of hooks, also accidentally catch sea turtles as bycatch.

Human development projects, such as beach construction and the building of sea walls, rock jetties, and other structures, reduce suitable nesting sites for female sea turtles. The lights, noise, and trash associated with these developments can disturb nesting sites, causing females to return to the sea without laying eggs. Climate change and rising sea levels further compound the issue by impacting the availability and quality of nesting beaches.

Pollution, including plastic debris and oil spills, also takes a toll on sea turtle lifespans. Leatherback sea turtles, for instance, often mistake plastic bags, plastic pellets, and balloons for their jellyfish prey, leading to intestinal blockages and reduced feeding ability. Oil spills can cause ulcers, organ damage, immune suppression, and reproductive failure in sea turtles, as well as decrease hatching success.

Poaching and illegal hunting for meat, shells, and eggs are additional human activities that negatively impact sea turtle populations. Six out of the seven sea turtle species are classified as endangered due to these threats. Furthermore, deforestation may indirectly threaten sea turtle nests by causing a rise in the water table, which could drown the nests.

Propeller and collision injuries from boats are also a frequent cause of injury and death for sea turtles, especially in areas with high levels of recreational boating. These human activities significantly impact the lifespan and survival of sea turtles, highlighting the need for conservation efforts and responsible human practices to protect these ancient creatures.

Sea turtles' natural predators

Sea turtles face a multitude of risks from natural predators throughout their life cycles, and are especially vulnerable as hatchlings.

Before they hatch, sea turtle nests may be raided by mammals such as raccoons, foxes, dogs, and wild pigs, as well as several species of crabs, insects, and microbes.

Once they emerge from their nests, hatchling turtles are at even greater risk from mammals, birds, and crabs as they cross the beach to the sea. During their frantic swim to deeper water, they are vulnerable to large bony fish, sharks, and sea birds.

Even once they reach deeper waters, the risks don't disappear. In these habitats, turtles are still consumed by large bony fish and sharks.

Adult sea turtles are perhaps more immune to predators, but they are not entirely safe. In Central and South America, American crocodiles and jaguars are a threat to nesting females, and in the Indo-Pacific, saltwater crocodiles prey on adult turtles on nesting beaches and in inshore waters. At sea, large sharks, especially tiger sharks, are the primary predators of adult sea turtles, although killer whales are also known to occasionally eat sea turtles.

Sea turtles have evolved several adaptations to protect themselves from predators, such as their hard shells and camouflage. They may also choose lower-risk habitats to reduce the hazard posed by predators like tiger sharks.

Sea turtles' reproductive life

Sea turtles have a long reproductive life, with some species living up to 50 years or more. The lifespan of sea turtles varies depending on species, size, metabolism, water temperature, and habitat. For example, the Kemp's ridley sea turtle has a lifespan of around 30 years, while the green sea turtle can live up to 80 years. The leatherback sea turtle can even live up to 100 years or more.

Sea turtles typically take decades to reach sexual maturity, ranging from as early as 7 years for leatherbacks to more than 40 years for some Australian populations of green sea turtles. Once sexually mature, sea turtles remain reproductively active for about another 10 years. During this time, they migrate long distances and face various natural predators, such as sharks and crocodiles.

The reproductive behaviour of sea turtles involves courtship and copulation. Courtship patterns vary, from aggressive interactions to more subtle approaches, such as the male vibrating his forefeet to titillate the female. Fertilisation is internal, and copulation takes place in the water just offshore.

After mating, female sea turtles come ashore to lay their eggs. They dig a body pit and an egg cavity, depositing 50 to 200 eggs, depending on the species. The eggs are soft-shelled and protected by a thick layer of clear mucus. The female then covers the nest with sand to hide and protect it.

The number of eggs laid by sea turtles varies by species, with smaller turtles producing fewer eggs. For example, the leatherback sea turtle lays an average of 50-90 eggs per clutch, while the hawksbill lays 140-160 eggs. Sea turtles typically nest every 2-4 years, and females may lay between 1 and 9 clutches of eggs per season.

Sea turtles' diet

Sea turtles have a varied diet, depending on the species. Some are carnivorous, some herbivorous, and some are omnivorous. Their diet also changes as they age.

Green Turtles

Green turtles are predominantly herbivores, eating seagrass, seaweed and algae as adults. However, as hatchlings, they are omnivores, eating jellyfish, snails, crabs, and shrimp. They have finely serrated jaws, like a saw, which help them tear grasses and seaweeds, and scrape algae off rocks.

Hawksbills

Hawksbills are spongivores, with a specialised diet of sponges. They have a sharp, narrow beak that helps them reach within crevices on coral reefs to find their prey. They also eat small amounts of tunicates, shrimps, and squids. Their digestive system can neutralise the sharp, glass spicules and toxic chemicals found in sponges, which makes them toxic for humans to eat.

Loggerheads

Loggerheads are carnivores, with strong, massive jaws that enable them to crush hard-shelled prey like lobsters, crustaceans, and fish. Their jaws are adapted for crushing and grinding. Hatchlings are omnivores, eating both plant and animal material.

Kemp's Ridley

Kemp's Ridley are omnivores at the beginning of their lives, eating seaweed and small creatures like crabs and snails. As adults, they become carnivorous, eating fish, crustaceans, molluscs, squids, and jellyfish.

Olive Ridley

Olive Ridleys are omnivores, eating jellyfish, snails, crabs, shrimp, and occasionally, algae and seaweed.

Leatherbacks

Leatherbacks are gelatinivores, with a diet consisting almost exclusively of jellyfish and other soft-bodied invertebrates. They have sharp, pointed cusps on their jaws that enable them to pierce their prey. They also have sharp, downward-curving spines in their mouth and throat, called papillae, which help them swallow soft foods.

Flatbacks

Flatbacks are mainly carnivorous, eating sea cucumbers, jellyfish, soft corals, shrimp, crabs, molluscs, fish, and seaweed. They have slightly serrated lower jaws and feed in shallow, soft-bottomed habitats, avoiding rocky or coral reefs. They are particularly fond of sea slugs.

How to protect sea turtles

Sea turtles are fascinating ancient creatures that have roamed the Earth's oceans for around 110 million years. They are a vital link in marine ecosystems, such as coral reefs and seagrass beds, and are of great cultural and tourism value. Unfortunately, human activities have put their survival at risk. The good news is that there are several ways we can protect sea turtles and help ensure their long-term survival. Here are some detailed, direct, and instructive guidelines on how to achieve this:

Reduce Human Impact

Human activities have significantly harmed sea turtle populations. To protect them, it is essential to address issues such as pollution, habitat destruction, and poaching. Reducing pollution, especially plastic waste, is crucial as sea turtles can mistake plastic for food, leading to fatal consequences. Enforcing laws and agreements to minimise the dumping of pollutants and solid waste into the ocean is vital. Additionally, establishing protected areas and reducing uncontrolled coastal development can help preserve their natural habitats.

Address Accidental Capture

Sea turtles often fall victim to accidental capture in fishing gear, which is one of the greatest threats to their survival. To mitigate this, enforcing the use of Turtle Excluder Devices (TEDs) and gill net regulations can significantly reduce turtle deaths. Working with fisheries to adopt more turtle-friendly practices, such as using "circle" hooks or special turtle excluder devices, can also help.

Protect Nesting Beaches

Nesting beaches are crucial for sea turtles, and it is essential to establish parks, refuges, or regulations to protect these areas. Reducing disturbances, such as artificial lighting, beach armoring, and limiting human impacts, can create a safer environment for nesting. Educating the public about the importance of these areas and the threats they face can also help foster a sense of conservation and protection.

Combat Overharvesting and Illegal Trade

Sea turtles are still harvested unsustainably for human consumption and the trade of their parts. Addressing this issue involves providing alternative livelihoods for communities dependent on turtle products and promoting the economic value of live sea turtles through sustainable tourism. Training and equipping local rangers to patrol nesting beaches and enforce laws against poaching and illegal trade is also essential.

Minimise Climate Change Impacts

Climate change has impacted the nesting sites and sex ratios of hatchlings. By working with communities to monitor and protect nesting beaches, we can help sea turtles become more resilient to climate change. This includes raising awareness about the threat of sea-level rise and the importance of shade for nests. Additionally, addressing the loss of foraging grounds due to warmer sea surface temperatures is crucial.

By following these guidelines and working together, we can make a significant difference in protecting sea turtles and ensuring their long-term survival.

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