Hawaii's Ancient Ones




 

Green sea turtles, known in Hawaii as honu, are one of the few species on the planet so ancient that they swam alongside dinosaurs during the Jurassic period.  These reptiles crawled into the sea around 150 million years ago where visitors can commonly spot them swimming in the surf off the rocky shores and beaches of Kaua‘i as they feed on sea grasses below the surface.

Named for the green fat underneath the honu’s shell, it is the largest hard-shelled sea turtle. Growing up to 45 inches and weighing as much as 200 to 400 pounds by the time it reaches maturity at the average age of 25 years, their heads are proportionally much smaller than that of other turtles, making their dark eyes appear even larger.

A common petroglyph carved into lava rocks, ancient Hawaiians often depicted the honu with its four flippers out as if swimming through the ocean, with a vertical line down its shell.  There are some Hawaiian legends, which claim that turtles were the first to guide the Polynesians to the Hawaiian islands, making the green sea turtle a symbol of the navigator that is able to find its way home time and time again—just as in real life.  Amazingly, the honu will swim hundreds of miles to its own birthing place to lay eggs.

After mating in the water, the female honu crawls above the beach’s high tide line during the cool of the night where she digs a hole with her hind flippers and deposits between 100 to 200 eggs.  After laying her eggs, the mother then covers the nest with sand and returns to the sea.  Somewhere between 45-75 days later, the hatchlings emerge and instinctively head toward the water.  As they scramble to the waves, predators such as birds and crabs hunt them while in the ocean seals and fish wait patiently. This is the most dangerous time in a turtle's life and a significant percentage of the hatchlings never make it to adulthood.

The Hawaiian green sea turtle was nearly extinct not too long ago as humans present both intentional and unintentional threats to the survival of the species. Intentional threats include continued hunting and egg harvesting.  However, even more dangerous are unintentional threats including boat strikes, fishnet entanglement, pollution and habitat loss.  An infectious tumor-causing disease known as fibropapillomatosis is also a problem in some populations.  The disease kills a sizeable fraction of those that it infects, though some individuals appear to have immunity.  Because of these multiple threats, many populations have declined giving them endangered species status and making it illegal to collect, harass or kill honu.  Due to federal and state protection laws and conservation outreach efforts, these turtles are happily becoming a frequent sight again.

Sea turtles spend almost all their lives submerged beneath the waves but must frequently breathe air for the oxygen needed to meet the demands of their vigorous aquatic activity.  With a single exhalation followed by rapid inhalation, sea turtles lungs are capable of conducting a rapid exchange of oxygen while preventing dangerous gases from being trapped during deep dives.  During routine algae foraging, a honu can dive for four to five minutes and surface to breathe for only about two seconds. Turtles can rest or sleep underwater for several hours at a time; but submergence time is much shorter while diving for food or trying to escape predators.

As turtles breathe air, it is extremely important not to disturb them, especially when they are surfacing.  If you come across the turtles playing in the surf while swimming or snorkeling, typically they are eating algae growing on the rocks off the shoreline.  By keeping a respectful distance of at least 15 feet you can enjoy these ancient creatures, while minimizing any disturbance.  Remember, spotting a honu bobbing in the waves is relatively easy, but having your camera ready to land a shot when they emerge for air can be a true challenge!

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