Posted by: The Amoeba | July 28, 2008

While Turtles Safely Graze

Another repost from Felloffatruck Publications, this one from 30 March 2008. Two reasons for bringing it back to light. One, Quilly’s posts on our visits with sea turtles get visited from time to time, and they link to this one. Which now you can read again (once the links get fixed). Two, a lot of people on O‘ahu are up in arms right now about an idiot (I hope only one) running around killing sea turtles for no apparent reason. I mean, it wasn’t too long ago when Quilly was swimming in a North Shore lagoon and felt a bump on her side.

“‘Scuse me.”

“Huh?” (That was Quilly.)

“I said ‘excuse me’. I’m hungry, and you’re blocking the path to the seaweed patch. Now would you mind …?”

Quilly splashed aside, and we followed the turtle to the grazing grounds, where we spent the next half hour trying, and failing (fortunately) to interrupt our companion’s dinner.

I just hope that wasn’t Honey Girl.

Anyway, it just seemed like a good time to resurrect this story.


On our recent two-day trip to Hawai‘i Island (the haoles call it the “Big Island”, not realizing – or, perhaps, not caring – that the kanaka maoli don’t necessarily appreciate having a name that means “homeland” dissed in this particular way) …

As I was saying. On our recent trip to Hawai‘i Island, Quilly hoped to see turtles. So, on the one day of the two on which I wasn’t working, and as she’s already related, we went to a place where we expected to find some – the promises made by our hotel’s advertisements having gone the way of most promises made in advertisements.

And it came to pass, as we were walking along the shoreline near the heiau, I was able to stand and point and say:

“Sea turtle!”

Where turtle?”

“There. Turtle.”

The embarrassing part of this story (not counting the Young Frankenstein ripoff) is, the two of us, including yours truly, The Amoeba, the Grand Protistan Master of Marine Biology, walked right past the spot where the turtle was – while other people were watching it – and never saw the thing. If I hadn’t happened to look back at a moment when the animal had its carapace above water, and watched the rock move …

For the next half hour, we sat and watched while this turtle, a mere fifteen feet away (it’s illegal to get any closer), paid attention to nothing but feeding its face. It’s illegal to get any closer, because the Green Sea Turtle is an endangered species and is protected by international, Federal, and Hawai‘ian State laws. Not that those laws stopped one kid from grabbing a turtle while we were there, and hoisting it into the air for his dad – and any wildlife officers in the vicinity – to see.

That face-feeding looked like hard work. There didn’t seem to be much more than bare rock for this oceangoing herbivore to eat. While we were considering this observation, I happened to look down into a crevice that was too small for a turtle to stick its head into. And saw this.

limu crevice

Most of the seaweeds growing in this crevice were limu aki‘aki, known to scientists (for the moment anyway, see *FOOTNOTE) as Ahnfeltiopsis concinna. Limu in Hawai‘ian means “seaweed”, and limu aki‘aki is one of the types favored by both sea turtles and humans. Though the humans usually prefer limu manauea, limu huluhuluwaena, or ogo with their ahi.

Where the turtles couldn’t reach, the limu growth was luxuriant. Where the turtles could reach, however, all the limu stalks were bitten off at the base:

bitten limu

Fortunately, this limu can form new growing tips from the bitten ends, and also can grow new stalks from a flat base that’s stuck like paint to the rocks. They must grow just fast enough to keep the turtles fed.

Around the corner, we found a sandy beach where turtles had hauled themselves up on the beach to bask themselves. There’s a lot more to this simple sentence than meets the first reading.

For one thing, sandy beaches are not all that common on the shoreline of Hawai‘i Island. Hawai‘i Island has, not one, not two, but three active volcanos on it. Most of the shorelines are black volcanic rock, from the lava flows that these volcanos spew out from time to time. A natural sandy beach is a thing to be cherished – and the one at Pu‘uhonua o Honaunau certainly was. So cherished, in fact, that the ali‘i claimed it for themselves. Only the nobility were permitted to walk it and land their boats on it. To the common people, the beach was kapu.

turtle kapu

It still is. Ropes and signs prohibit the mere tourists from striding the sacred sands. Not only as a sign of respect to Hawai‘ian culture, but more importantly (given what Americans have historically felt about anybody else’s, especially English, nobility), as a sign of respect to the turtles, who will only haul themselves up on beaches where they feel they won’t be pestered while basking in the sun.

Apparently, the “basking in the sun” business is something of a mystery to people who study the Green Sea Turtle. Of all the half-dozen sea turtle species, the Green is the only one that indulges in sunbathing. I searched the Internet for awhile, and found nothing other than arm-waving explanations (such as “they like getting warmed up in the sun just like us”) for this practice.

I venture to suggest something.

turtleback with algae

Here’s a shot of our friendly grazer with its back out of water. You might notice that the back of the shell (carapace) looks less clean than the rest of it.

turtleback with algae close up

In fact, it looks like there’s stuff growing out of it.

Well, there is. Algae. Quite a bit of it. And it’s not like the turtle can reach back with a wire brush and scratch itself there to get rid of it. In freshwater environments, there are algae (for example, in the green algal genus Basicladia) that grow only on the backs of turtles. And their growth can get kinda frightening.

Like this.

So what’s a poor turtle to do, if it doesn’t want to turn itself into a floating seaweed garden? It can’t bite the algae off, it can’t scrape it off. What’s left?

Burning it off. That’s what. Hence the basking.

And the need for people to leave the blessed turtles alone while they’re basking. So the beaches where the turtles haul themselves ashore are kapu. Which is fine with me.

Time constraints prevented us from getting into the water with these turtles. I understand that’s quite an experience. Maybe next time.

*FOOTNOTE: The scientific name of living thing X is supposed to serve both as a label with which to identify X, and as a clue to the other living things to which X is related. With many forms of life including algae, this practice causes lots of problems. Mainly, because most algae were given scientific names based on what they look like, and in recent years we’ve found that algae which look alike may be no more closely related to each other than you are to the pineapples you just had for dessert.

I looked up DNA sequences that have been obtained from algae identified as Ahnfeltiopsis concinna, and compared them to DNA sequences from other closely-related marine algae. I found that species placed in the genus Ahnfeltiopsis are not all closely related to each other. Which means that at least some of the algae now assigned to the genus Ahnfeltiopsis need to be placed in some other genus – in other words, they need a new scientific name.

It turns out that, according to the DNA sequences I investigated, Ahnfeltiopsis concinna belongs to the same group as Ahnfeltiopsis linearis, the “type” (more or less, the first-named) species of Ahnfeltiopsis and therefore the “benchmark” for correct assignments of species to this genus. So it looks like I can keep Ahnfeltiopsis concinna as the correct scientific name for limu aki‘aki, right?


Because that same group of species also includes plants identified as Gymnogongrus griffithsiae, the type species (benchmark) for the genus Gymnogongrus. Which genus was first described in 1833; Ahnfeltiopsis was first described in 1992.

That means that I need to throw away the name Ahnfeltiopsis entirely, because it’s a synonym of Gymnogongrus and was published later, and change the scientific name of limu aki‘aki to Gymnogongrus concinnus [sic] …

If and only if the specimens from which the DNAs came that were assigned to Ahnfeltiopsis concinna and A. linearis and Gymnogongrus griffithsiae were in fact correctly identified – an if that is by no means a sure thing. And if and only if other kinds of analyses (including those from other DNA samples) give the same answer as the one that I looked at.

There are smarter and better informed people than I working on this question as I write. Meanwhile, I’ve got a headache. I can just imagine what you’ve got, dear reader. If you got this far.

  – O Ceallaigh
Copyright © 2008 Felloffatruck Publications. All wrongs deplored.
All opinions are mine as a private citizen.



  1. You quit speaking English when you got to FOOTNOTE*

    I’m glad you reposted this.

  2. Love, you knew I spoke mostly foreign languages before you met me …

  3. Cool pictures. I like turtles. I saw a snapper on the riverbank a few weeks ago.

  4. i remember this, and the previous one. but they are still an enjoyable read 🙂

  5. nice all!!!!!!!!!!!!

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