The childhood dream to swim alongside a sea turtle is shared by all who grew up fascinated by wildlife. Perhaps it is the nomadic nature of these sea fairing transients that seems to tie the world’s ecosystems together. These reptiles can be found in oceans worldwide, from Alaska's Gulf Coast to the shores of Florida, Hawaii, Guam, Australia, and beyond. Like the polar bear, African elephant, or kangaroo, sea turtles are a landmark species. Anyone—wildlife enthusiast or not—can recognize a sea turtle. They are icons of nature’s untamed beauty, as well as its fragility in the face of environmental atrocities. They teach us to appreciate what we have, and to protect all that we stand to lose.
Most people will only ever read about sea turtles in books or watch them on film. The idea of a 1,500 pound leatherback, hauling itself through the sea at over 20 miles per hour, or the prospect of hundreds of thousands of Olive Ridleys coming ashore to nest in a famed arribada, seem almost too fantastic to be true. Turtles tease us with the wisdom of time itself, locked away in their boney shells. They are immortalized in our pop culture in the form of logos, T-shirts, and children’s movies. There is perhaps no creature so familiar, and yet so mysterious; for we know little of the daily lives of these sea-fairing giants.
As a young boy, I remember curling up on the couch with my parents to watch our nightly episode of The Crocodile Hunter. Steve and Terry Irwin introduced my generation to the world of wildlife. The imagery of Steve coaxing an elderly and emaciated green sea turtle into an Australian harbor has never left me. The khaki-clad duo didn't interfere with the aging reptile; they admired it for its tenacity and allowed nature to take its course. Every child who watched their show dreamed of wildlife encounters, and longed to chase adventures on far off islands.
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This past December, I had the chance to visit the big island of Hawaii. After spending all day on a plane, I had to pinch myself to check that I wasn't still a daydreaming eight-year-old. This was my first time to the Aloha state and I had little idea what to expect. Tracking down some of Hawaii’s rare and endemic wildlife was the first thing on my mind. Sitting over 2,000 miles from the nearest mainland, Hawaii’s isolation makes it a laboratory for evolution. Few plants or animals made it to the island; there are no native land dwelling reptiles, amphibians, or mammals (except for a bat). Those (likes birds and drosophila flies) that did make it to Hawaii’s rocky shores, diversified into countless species.
Hawaii is the most isolate archipelago on earth. This chain of volcanic islands spans 1,500 miles across the middle of the Pacific Ocean. Hawaii’s highest mountain Mauna Kea rises over 33,000 feet from sea floor to summit, making it taller than Mount Everest. The Hawaiian chain was born from a magma hotspot that has been pushing up through the ocean floor for millions of years. As the pacific plate drifts northwest (at about the same rate finger nails grow), the hotspot continues to spit out new volcanic islands, while older, extinct volcanoes sink under their own weight. Today, 8 main islands and over a hundred smaller islands make up the Hawaiian chain.
One creature that had no trouble finding its way to the islands was the Honu, the Hawaiian name for the green sea turtle (Chelonia mydas). Sea turtles can travel thousands of miles across the ocean as they move from feeding grounds to breed. Five species of sea turtles are known to frequent Hawaii’s waters, but only the green is seen with any regularity. These gentle giants feed on seaweed, jellyfish, and crustaceans around Hawaii’s shores. Few turtles actually nest on the main islands; most lay their eggs on the French Frigate Shoals—a tiny island in the Hawaiian chain, comprised of only 67 acres.
During the first few days of the trip, we had no luck finding these apparently common reptiles. After striking out at several beaches, we decided to drive to Punalu’u, one of the best known black sand beaches in the world. The black sand is actually hardened lava rock from the nearby Volcanoes National Park. Lava spewed into the sea by Kīlauea, one of the most active volcanoes on earth, is pulverized into a fine, black sand. Green sea turtles are a common visitor to Punalu’u along with the occasional hawksbill sea turtle. Upon arriving at the beach, I wasn't disappointed.
Like a smooth, rounded stone that had been weathered by the ocean surf, the turtle’s carapace glistened the same shade of black as the sand. Huge, wrinkled eyelids hung slackly over fist-sized eyes. Oblivious to the gawking beach-goers, the turtle slept, only moving to lift its head above the occasional wave. Like a painted turtle soaking up sun rays on a log, this sea-fairing behemoth was thermoregulating. Hawaii, Australia, and the Galapagos are the only places on earth where green sea turtles come ashore to bask. Most green turtles, along with other sea turtle species, never leave the water except to nest. They bask at the ocean’s surface, using patches of seaweed to stay buoyant.
It isn't fully understood why some sea turtles bask on land while others do not. Basking helps kick start the metabolism, aiding digestion and improving the immune system. Egg development may be another benefit, but since both male and female turtles can be seen ashore, this isn't the whole story. Seasonal fluctuations in the number of beach baskers points toward water temperature as a deciding factor. Scientists have found that when sea temperatures are below 23°C the turtles are more inclined to come ashore. February through April provide the best chances to see turtles hauled up on the beach.
Most reptiles are not thought to be social, and the same holds true for sea turtles. However, green turtles often bask in close proximity to one another rather than spreading out. Large, off-shore congregations are also common during the breeding season. As I moved down the beach, I came across three more of the huge turtles, all within a few feet of one another. With shell lengths of a meter or more, these were the largest wild turtles I had ever seen. Their huge flippers sunk into the black sand like leathery wings. Not your ordinary, everyday box turtle.
As global sea temperatures rise, land basking may be on the decline. The waters around Hawaii are increasing by 0.04°C per year—three times higher than the global average. By 2039, Hawaii’s waters will be permanently warm enough to sustain ocean basking. By the century’s end, sea temperatures around the world will have warmed beyond the land basking threshold. With the benefits of land basking still shrouded in mystery, it is unclear what warmer temperatures will do to sea turtle ecology.
6 of the 7 sea turtle species are listed as endangered. Like many of Hawaii's native wildlife, the green sea turtle was almost wiped out by the mid-1900s. Their name comes not from the color of their skin (which is usually brown), but from the green shade of their fat and cartilage. These turtles were exploited for their meat, shells, and eggs for centuries. The federal government established protection for these turtles in the 1970s making it illegal to hunt, harass, or even touch these giants.
Despite protection, sea turtles still face a host of threats. The illegal wildlife trade destroys countless nests for sale to foreign markets. Adult turtles are illegally harvested for their meat and their leathery skin is used to create commodities. Human development of important turtle nesting beaches and degradation of the ocean through pollution are also major problems for marine wildlife.
Found in sea turtles the world over, fibropapillomatosis or FP is a herpes virus thought to be linked to pollution. This disease causes enormous cauliflower-shaped tumors to develop on the turtles’ skin and internal organs. FP obstructs vision and locomotion, making turtles vulnerable to predation. Despite being first observed in the 1930s, this disease is still poorly understood.
Possibly the greatest threat to sea turtles is being accidentally caught by fishing vessels. Turtles that become trapped or entangled in nets often drown and are thrown back as bycatch. Fisheries may discard as much as 40% of their catch as undesirable. Turtles are not the only creatures to fall victim to these snares. Sea birds, dolphins, sharks, and seals are common victims of bycatch. To learn more about threats to sea turtles and things you can do to help save them, visit seeturtle.org.
As an aspiring turtle researcher, getting to see wild sea turtles at the black sand beach was a thrill. I even had the chance to snorkel with two huge individuals. They carelessly drifted past me with the bulk and grace of an armored submarine. I tried to keep a respectful distance, but the turtles often swam towards me faster than I could retreat. They didn't seem to mind my presence, or even take much notice as they munched away at algae-covered rocks.
As I looked closer at one of the huge reptiles, I noticed something odd near the front of the animal's shell. It was a white, rectangular patch of epoxy. Could it be the remnants of a radio transmitter? I stood there speechless for several moments, paralyzed by the coincidence. It didn't seem possible, but halfway across the world I was seeing an echo of my own Ohio box turtles in this huge prehistoric sea creature. These endangered marine reptiles have given me a new perspective and an even greater appreciation for wildlife conservation and research. Perhaps some day I'll be the one tracking them.
Next on my list: Hawaii's endangered native forest birds.
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