AboutSeaTurtles
TURTLEHawaiian Green Turtle
Kingdom: Animalia  Phylum: Chordata  Class: Reptilia  Order: Testudines 
Family: Chelonidae  Genus: Chelonia  Species: mydas 
Scientific name: Chelonia mydas
Common name: Hawaiian Green Turtle
Hawaiian Name: Honu

Hawaiian Green Turtles are a genetically isolated population of the Green Turtle (Chelonia mydas) and is sometimes known as the black form of the Green Turtle. They grow to a maximum length of about 4 feet and up to a weight of 440 pounds.

TURTLETurtles are reptiles, covered with a scaly skin typical of their Class, and returned to a life in water from terrestrial ancestral stock more than 200 million years ago. Turtles, like all reptiles, are ectothermic meaning their body temperature tracks the environmental temperature. This confines them to the warmer ocean regions such as Hawaii. Their bodies are encased in a heart-shaped bony “shell” called a carapace that is composed of fused backbones and ribs along the back and its underside side is protected by a boney plate (the modified breastbone), called a plastron, that is fused to the carapace. Turtles have evolved flippers from modified front legs that propel the animal like a marine bird such as a penguin. Like penguins, their hind feet are modified as rudders.

Hawaiian Green Turtles have a small head and jaw-line edged by horny plates with which they can crop seaweeds and consume other encrusting organisms such as sponges from the rocks. Although their color varies the genetically distinct race of the Hawaiian Green Turtle is often dark in color and frequently tinged green by algae encrusting their carapace.

Most marine turtles spend almost their entire lives at sea, only venturing out on to land to nest. Hawaiian Green Turtles by contrast also display the unusual habit of dragging themselves ashore frequently to bask in the sun.

Green turtles are resident around all the large Hawaiian Islands year-round. Adult females make migrations every 2-4 years (males every year) to the Northwestern group of islands, with most of them concentrating around French Frigate Shoals, to breed. Turtles have a strong affinity with their birthing beach and reportedly will return time and again there to nest. Turtles mate in the ocean and, subsequently, the females haul out on the beaches, usually at night, to dig a nest in the sand above high tide level. Using her fore-flippers she’ll dig a conical pit in the soft sand. The nest cavity is excavated with the hind flippers and this is where she will lay between 70-200 eggs.

The number of eggs and the number of nests laid varies with each female. Incubation in the sand lasts between 45-75 days. The sex of turtle hatchlings (as with some other reptiles) is determined by the heat of the sand in which the eggs reside and not their chromosomal make-up (true in most birds and mammals). Cooler sand temperatures create males and warmer sand, females. Determination of turtle sex is controlled by the production of temperature-induced hormones.

TURTLEWhen the turtles hatch out they scamper down through the surf and out over the reef into the open ocean. They spend the first 4-10 years on the high seas in deep water often at the convergence between warm and cold currents where they feed on small free-swimming creatures. Not many young turtles of this age survive the dramas of their years in the deep sea. Eventually they leave their open water home to settle in the shallows around the large Hawaiian Islands where they lead a more sedentary, largely herbivorous, lifestyle. Turtles in Hawaii consume more than 80 species of seaweeds as well as a lot of creatures encrusting the rocks, particularly sponges and tunicates. It takes the young turtles an average 30 years to mature and become reproductively active. Certainly green turtles live to 50 years old. It is thought likely that they may live to be more than 80 years old.

There are few predators that take adult green turtles beyond people and Tiger sharks. Their eggs are consumed by all sorts of beach scavengers like ghost crabs and elsewhere in the world they are excavated and consumed by people and feral animals such as pigs. Historically, green turtle meat and eggs were an important part of the staple diet of ancient Hawaiians and their oil was used to treat skin ailments. Not today.

In addition to predation, turtles have suffered in the last 50 years from disease known as Fibropapillomatosis, attributed to a virus that causes tumors on the skin and internal organs. The tumors interfere with swimming, eating, breathing, vision, and reproduction. Turtles with heavy tumor burdens often die. Currently, this affliction seems to have waned and, as a result of their conservation, Green Turtle populations in Hawaii have rebounded.