Updated: Aug 9, 2022
Green sea turtles are probably the most common species of megafauna (larger animals) that I see on dives. Although you might see these guys on almost every dive, you can’t help but still be excited to see them. However, I have also seen so many divers take advantage of these curious and charismatic creatures. Here is everything you need to know about the Hawaiian green sea turtle before getting in the water!
Hawaiian Green Sea Turtle Biology
The green sea turtle can grow to be one of the largest species of hard-shelled sea turtles. They can grow up to 3-4 feet long and weigh between 300-350lbs. Their carapace has five scutes running down the middle and four scutes on each side. (NOAA, 2020). The plates on the shell help to identify species while the patterning along the sides of the head can be used to identify individuals. Most of the Hawaiian population of green sea turtles will forage in the main Hawaiian Islands and then move into the Northwestern Hawaiian Islands to nest.
Hawaiian green sea turtles are one of eleven distinct populations of green sea turtles. (Seminoff et al. 2015). The Hawaiian population of green sea turtles is considered a threatened population under the Endangered Species Act. (IUCN, 2004). They are the largest marine herbivore in the Hawaiian Islands feeding off seagrasses and seaweeds along the coastline. Their name comes from their diet as the pigment in the seagrasses gives their fat a green color. Since green sea turtles feed in close proximity to the shoreline they are often one of the most common species that divers and snorkelers encounter in Hawaiian waters.
Green Sea Turtles in Hawaiian Culture
As the only reptile native to the Hawaiian Islands, the green sea turtle, Honu, is rooted deep in Hawaiian culture. According to Hawaiian storytelling and history the honu was created when Aiai drew marks on a rock near the ocean which turned into a turtle. The honu symbolizes a connection between people, land, and the ocean. As the sea turtle was originally created from part of the earth, the honu must return to land to lay its eggs. (National Park Service, 2002).
The honu has been part of many Hawaiian tales as a guide, foundation, and defender to the islands. One story depicts “Kauila”, a honu who could shape shift into a human who would watch over the children playing in Punalu’u Beach on the Big Island. (HaleKupuKupu, 2018).
The honu was also considered ‘aumākua to some families and were worshipped and cared for. ‘Aumākua are considered to be ancestral spirits of one’s passed family members. While ‘aumākua are not visible to the human eye it is believed that they could posses the form of certain inanimate and living things to make appearances to their living relatives. This is not to say that a family would see every honu as ‘aumākua, but the ‘aumākua would posses a certain honu for a particular purpose.
How To Interact With Green Sea Turtles
As with any wildlife, I always recommend moving slowly while diving with green sea turtles. Any sudden movements on your end may startle or spook the turtle. For the best interactions you will want to approach slowly and cautiously. Some individuals may take more interest in you while others might be more skittish and leave. Do NOT chase after the turtle! If it wants to leave, let it go! Chances are, you will probably see another one later in your dive that might be more friendly.
Understand Signals To Go Away
Sea Turtles, like any animal, will use their body language to communicate with other animals. Just like understanding shark behavior can help you have better interactions, understanding sea turtle behavior can too.
A green sea turtle that is turning its shell towards you isn’t just showing off. This behavior is used to express fear. The shell is the turtle’s greatest form of protection. When hunted the sea turtle will turn the shell in the direction of the predator, probably tiger shark, to use as a shield from sharp teeth. If you are swimming with a sea turtle and they start giving you the shell it is the equivalent of a person saying “talk to the hand.” Give them a little more space or leave that individual alone. It is better to move on in hopes of finding a friendlier individual anyway.
Ever seen sea turtles mate? I have! It is awesome!….and a little boring. We want our green sea turtle populations to continue to be healthy and grow. If you see some sea turtles making little baby sea turtles give them their space. Your presence could stress out the animals and make mating less successful.
Keep Your Distance
Hawaiian green sea turtles are a federally protected species. This means if you get too close you could get fined. While there is no law specifically stated exactly how close you are allowed to get to the green sea turtles DLNR (department of land and natural resources) and NOAA recommend about 10ft. Since guidelines are not incredibly specific it is best to use caution when interacting with the Hawaiian green sea turtles.
It is 100% illegal to harass, chase, disturb, feed and/or touch Hawaiian green sea turtles! Respect the wildlife as you would want to be respected. I have seen too many times uneducated and overly excited tourists and divers attempt to ride, pet, hug, etc. the sea turtles. While the Hawaiian green sea turtles can be absolutely adorable, they are still wild animals. Please give them space.
THE TURTLE DANCE
Not sure how to ensure you are not breaking any of these rules? It’s called the turtle dance and it goes like this: 1) Put you hands in the air like you just don’t care! Think raise the roof but more of a “look I am not touching them motion.” 2) Back that thang up! Slowly move backwards away from the sea turtle if it is approaching you.
Just because you now know that humans are not allowed to approach green sea turtles doesn’t mean the turtles know that. The reality is that while most sea turtles are somewhat shy of people, I have met quite a few that absolutely love them! Some green sea turtles have absolutely no personal space boundaries. This is where the “turtle dance” comes in handy!
Sea turtles can and will bite you if you stick your fingers too close to their face. I have had quite a few try to munch on my hair thinking it was seaweed! Just because they are cute doesn’t mean they are cuddly. Be just as cautious when swimming with green sea turtles as you would with any other large animal in the ocean.
Importance of Green Sea Turtles in Hawaii’s Ecosystem
The Hawaiian green sea turtle is an extremely important herbivore in the Hawaiian reef ecosystem. Unlike populations of green sea turtles in other parts of the world, the Hawaiian green sea turtles feed on algae commonly found along the coral reefs. (McCutcheon et al. 2003). Not only are the turtles feeding on native algae but they also feed on invasive species that can have adverse effects on the corals. (Russell & Balazs, 2009).
Algae cover on coral reef can prevent the corals’ ability to use their zooxanthellae to photosynthesize. While the algae itself can use photosynthesis, the coral provides additional habitat structure and protection to species that call the reef home. The green sea turtles play a role, along with other herbivorous species, in maintaining a healthy level of algal cover on the reef.
Hawaiian Green Sea Turtle Conservation
Like sea turtles in many regions of the world, the Hawaiian green sea turtle has many human impacts to worry about. Boat strikes, fisheries bycatch, pollution, habitat destruction, and human/pet introduced diseases all play a role in population loss. Although green sea turtle populations continue to slowly rise since the outlaw of hunting in 1978, they are still considered a species we need to keep a close eye on.
Fibropapilloma virus (FP) is a disease that occurs in green sea turtle populations around the world but has been extremely prevalent in Hawaiian populations. FP is a form of herpes virus that causes large and contagious tumors on sea turtles. Don’t worry, humans cannot contract FP! It is thought that FP infected algae along the Hawaiian coast through runoff and as the turtles fed on the algae they acquired the virus. Cleaning stations where fish may pick at one turtles tumors and then move on to another healthy individual may be aiding in the spread of the virus.
In Hawaii, FP has been responsible for many turtle strandings and death. However, the islands are seeing a slow decline in the spread of the disease. Reasons for this decline are unknown.