Green Sea Turtles, Your New Friends

(Last Updated On: January 18, 2017)

Green Sea Turtles, Honokeana Cove 200pxScience Fact:  Green Sea Turtles, “honu” in Hawaiian, are denizens of the deep that may seem sleepy and relaxed.  However, a sea turtle shows quite a personality when you watch him engage in his “sea turtle” behavior.

When you snorkel at one of Maui’s friendly coves, your attention is first drawn to the colorful fishes darting in and out of the coral.  But as you swim around you may suddenly find a gigantic shape looming over your shoulder, or rising up beneath you.  You are in the world of sea turtles and because you are neither good to eat nor likely to make a meal of them, they go about their business without paying attention to you at all.  Nevertheless, having a creature the size of a desk nudging close to you can be unnerving.

As you look below, you then discover that the dark shapes you thought were rocks are actually this turtle’s sisters, cousins and aunts, lounging around on the sandy bottom, often partially snuggled under an outcrop of coral.

The casual snorkeler might think that all sea turtles do is sit on the sand, coming up rarely, every hour or two, to breathe.   However, a little observation shows a variety of characteristic behavior:
– Feeding:   Almost any time of day, sea turtles may graze on algae growing on rocks or attached to coral.  However, to really see the feast in progress, wait until dusk.  Then the sea turtles start feeding in droves and because of the increased activity, they need to breathe every few minutes.  Thus you will see shell backs appear and heads popping to the surface, over and over until night falls.
– Basking:  Sea turtles, like other reptiles, are cold-blooded and regulate their body temperature by seeking warmer or colder water, or by basking in the sun.  If you are on a quiet coastline (without swarms of noisy visitors), you may see a turtle lying on rocks near the shore, apparently dead.  But it is not dead, and in fact due to wildlife protection laws you are forbidden to approach it or bother it.  If you watch long enough you will see it ever so slowly rouse itself, then move in lurches back to the water, where it will launch itself and suddenly swim away as gracefully as you might imagine.  Besides regulating the turtle’s body temperature, basking is said to elevate sea turtles’ metabolism, strengthen their immune and digestive systems, and provide vitamin D to process calcium and strengthen the turtle’s shell.

Two green sea turtles basking at Honokeana Cove

Two green sea turtles basking at Honokeana Cove

– Sex:  Sea turtles have sex like many other animals, that is to say, “doggy style”.  However, like everything else sea turtles do it tends to be v-e-r-y s-l-o-w.  Sea turtles most often get the urge near a nesting beach, but we have also seen them making little turtles in Honokeana Cove because it is quiet and secluded.  If a turtle floats on the surface for a long time, rocking from one side to the other, look closely and you may see two heads catching air and the edges of two shells.  The male has hooks on his front flippers with which to grab the front edge of the female’s shell, so she is unlikely to slip away accidentally or even intentionally.
– Cleaning Stations:  Because sea turtles may live 50 years or more they have plenty of time to accumulate algae on their shells.  The algae creates drag in the water, which increases their energy expenditure as they swim.  Like other large marine animals, sea turtles have evolved a symbiotic relationship with small fishes: sea turtles will approach a cleaning station and “pose” or hover, almost stationary.  Small fishes cluster around, nibbling algae from the sea turtles’ shells, flippers and necks.  Cleaning occurs at specific sites.  For example, Honokeana Cove has a number of coral outcrops, and at one of them near the north central part of the Cove one or two sea turtles can almost always be seen, having their shells cleaned. Other sea turtles being cleaned may be seen HERE.

Science Speculation:  Green sea turtles are one of the visible successes of the global species conservation movement.  Once hunted to near extinction, sea turtles have made a strong comeback with the assistance of protective laws in many countries, including the U.S. Endangered Species Act and State of Hawaii wildlife laws.  Nevertheless, worldwide they are still threatened by hunting and egg-poaching as well as by fishing nets and loss of habitat.  In addition, survivors sometimes suffer from excessive attention and disturbance by well-meaning but unthinking tourists.  However, well-thought-out guidelines for reef and marine life protection are readily available.  Green sea turtles are one of the remaining magnificent creatures still living in their natural habitat, yet close enough to tourist areas that they can be enjoyed by any visitor.

Have you seen green sea turtles in the wild?  What kinds of activity did you observe?

Photo Credit: www.honokeana-cove.com

Comments

Green Sea Turtles, Your New Friends — 2 Comments

  1. Something you said made me wonder — if they feed mainly at dusk (and perhaps dawn?), the question is, why? With other animals it’s more obvious … something related to their natural predators, or related to what they eat themselves, or perhaps temperature. But with turtles it isn’t so obvious because their food source is immobile, the water and air temp is pretty constant in the tropics, and their own vision acuity would presumably be best in mid-day. What animal preys on turtles, and would dusk be safer for turtles than mid-day?

    • Charles, you’re quite right that the preferred feeding times turtles exhibit begs for an explanation.

      You mention the predators of sea turtles: for adult turtles the main predators are sharks, especially tiger sharks, and human beings. Hatchlings are prey for birds, dogs, just about any nearby carnivore. The best sources I know on this subject are an Australian website (http://www.mesa.edu.au/turtles/turtles02.asp) and another less academic but still useful site (http://www.seaturtle-world.com/sea-turtle-predators/).

      The latter site comments that noise may keep turtles from coming ashore to lay eggs, and I have observed that turtles are usually not seen basking when people are nearby: these observations suggest that turtles avoid people and commotion, and that makes sense because humans often prey upon them. Turtles come up to breathe throughout the day when there are swimmers and surfers present but this is only every hour or so, so they are not close to people for very long.

      Sea turtles do take occasional snacks of algae throughout the day. However, they save their more intense activity such as vigorous feeding, which requires much more frequent breathing, for times when the water has few human inhabitants. This allows them to keep their distance from people, although individual turtles seem to ignore people or even show curiosity about them. I see turtle heads bobbing up at dusk and I’d bet they are also feeding at dawn while I am sleeping, since the Cove is mostly empty of humans at those hours.