Tahiti Lagoon Getaway 3: The Weird & Wonderful Marine Life

When I decided to spend six days in a Tahitian lagoon, I already knew that I wouldn’t mind. The reason is that I am an ecologist at heart and by training, and I have a soft spot for the sea. I knew I’d be spending my days watching out for marine life in the lagoon. I’d never spent the night on the water before, and I was looking forward to it.

So what can you find in southern Tahiti, in late spring?

Marine Life from the Boat

If you want to have wildlife encounters, do yourself a favour with these two things:

1. lots and lots of time; and
2. be as non-disruptive as possible within that lots and lots of time.

There’s a reason why anglers must be capable of contentment being absolutely still, doing (mostly) absolutely nothing.

Now I’m not the best at this. My attention span isn’t that long. I can stay still, but I do get restless after a while. But the early warmth of Tahiti’s sunlight helped to rouse me out of the cabin in the mornings, and the catamaran’s lights made the nighttime solitude more pleasant, staring into the darkness of the lagoon.

Watching marine life from the surface

In late November, the lagoon is often glassy still. In the mornings you’d see the food chain in motion. Seabirds diving for their meal. Schooling fish, leaping together out of the water; and you know without having to see that beneath, there’s probably a barracuda in pursuit.

The marine food web is dynamic; there is always motion. Its contests of life and death are fast. Unless you’re standing by with a camera, they’re over and done with before you can move.

Marine life around the boat

In general, fish life are attracted to any kind of structure in the water that might give protection, or possibly harbour food. So, if the water is clear enough, fish watching is very pleasant off the side of the boat. If there’s coral somewhere, there’s going to be damselfish. The sergeant majors liked to come swim among the algae growing on the hull of the boat.

To my pleasure, various kinds of pufferfish also liked to come over. It’s always nice to see pufferfish, because they’re cute. They’re one of the more distinctive reef fish, because of their bloaty ungainly shape. They’re also one of Felix’s favourites. He refers to them with the Japanese word, fugu.

Lagoon life at night

The lagoon was very dark at night, so I didn’t expect to be able to see anything. I was content merely hearing the sounds of marine life occasionally breaking the water. Besides, usually I would be chatting with Felix, and preoccupied.

However, one of the nights he was on shore, fulfilling an invitation. That night, after I had finished brushing my teeth on the aft deck, it occurred to me to look beneath the boat, through the slits of the planks. And I instinctively recoiled.

There were alien-looking things down there, that did not move like fish!

The alien thing in the lagoon

Curiosity won out. I peered between the slits again, directly under the LED light. The alien things were small, but a few were about a foot long. A fish size, but they weren’t fish. It was hard to see their full bodies because they were constantly moving, circling around the light.

They were close to the surface for some reason, and eventually I reckoned that their bodies were probably flat, and maybe only 1-2 inches wide. Yellow, with maybe two lengthwise red stripes – though it was hard to be sure since the water ripples could have masked the pattern.

It was their movement that was unsettling. They were sinuous like eels, even though they’re flat. Twitching in the water. There were about a dozen of them under the light, but they were different sizes and they were not schooling – each individual moved independently. Were they feeding?

Though repulsed, I turned on my phone flashlight, and shone it through the gap. With the extra light, I could see that the body tapered at (what I assumed to be) the head, to a blunt mouth end. That end moved left and right in a sort of sensing motion, reminding me of a snout. The other end, the ‘tail’, tapered more gradually to a smaller blunt end.

I told my friend Cristin about it soon after (she has an encyclopaedic memory). I told her I was perplexed because it’s like a flatworm, but I found it in the water column like a fish. “Maybe it’s a ribbon worm,” she said. “They’re pelagic, and you can find them in the Pacific.” I looked it up later, and she might be right.

Snorkelling & Watching Sea Life

Of course, you’d expect the lagoon life to be more interesting when you’re in the water. And indeed, that’s the case. However, if you’re going snorkelling in a lagoon from a boat, don’t forget to start with the boat itself!

Unless the boat has just come back from dry docks, there might be things attached to the hull. This was my first opportunity to observe it at close range. Now, there wasn’t a lot of marine life (there wouldn’t be, on a reasonably maintained boat). But I did find an interesting mollusc with whiskers that pulsed in the current. Also, it was fascinating to see the gas bubbles on the algae, as it photosynthesised.

Marine life on the sandy bottom

The part of the lagoon immediately around the boat were stretches of sandy bottom. I should hope so; if it were coral, the boat’s anchor would damage it. There were fledgling coral outcrops here and there, but on the whole it was sand.

I’m often lulled into thinking sandy bottoms aren’t very interesting, even though I know better. Sure, you wouldn’t often see as many things as on the coral reef. But when you do see cool stuff and not have the camera, you’ll regret it! On my first day snorkelling, I didn’t bother since I didn’t plan to go far and the sky was overcast. Of course, that’s when I saw a stingray and a sand-coloured eel. Didn’t see them again in the days after.

Benthic invertebrates (the critters crawling on the bottom)

Sandy bottoms usually have lots of invertebrates (things that don’t have spines). I saw lots of sea cucumber, many of them with a cool red-and-black colouration. Others seem to have algae growing all over them.

I found not one, but two triton shells in the area. Now, this was the first time I saw triton shells in the wild. These snails are usually over-harvested because of their pretty shells, so I’ve never seen them in Southeast Asia.

I wasn’t sure whether these two were alive. They were remarkably still and the shells looked rough. Of course I didn’t flip them over to find out, because if they were alive, that would be very bad behaviour. I saw them again, I think, and their locations had changed. Maybe the waves knocked them about. Or maybe they really were alive and they moved.

Sustainability PSA: Tritons are the predator of crown-of-thorns starfish. When tritons are removed from a reef, these starfish can get out of hand, and overgraze the coral. Do not buy triton shells.

Fishes in sandy zones

There are usually not as many fish in sandy areas. One reason is because it’s a very exposed area. You can get eaten from many directions, including from above and below. A lot of fish that hang out in these zones are really pale, or transparent, for obvious reasons. Others are speckled or coloured like the sandy bottom, and they don’t move around much.

A common fish that I really like in these zones is the trumpetfish (also called cornetfish). Look at them, they’re like pencils! Gobies are also very common. But mimicry is way more advanced underwater than on land. I saw a fish that I thought was a goby, because it was coloured like one, and stayed close to a rock like one. But I couldn’t ID it from my books or on iNaturalist. It was only when I uploaded a zoomed-in photo on iNaturalist that I realised that it was actually a perch.

Occasionally you find a random coral fish. I came across pufferfish sometimes, snacking on the seafloor. Once in a while there would be a blackbar triggerfish zipping across from one bommie to another. Of course, I keep a healthy distance from triggerfish in general!

And of course, there was the moray eel I stumbled upon. I have since found I can’t identify exactly which kind of moray it was because I needed to have seen whether the inside of its mouth is white or speckled. And I would definitely not ever be near enough to a rearing moray to ever find out!

Exploring the lagoon’s coral life

The coral reef in this part of Tahiti’s lagoon is not exactly the healthiest. It’s extensive, but the lagoon is very shallow. This makes it more likely that the lagoon temperature could rise beyond what coral can tolerate. Consequently, the lagoon reef shows signs of bleaching frequently, but also re-growing.

Considering the reasonably good condition of the reef, there were not that many fish. There’s a reasonable diversity, but not a lot of it. Generally this means the reef is fished, and maybe overfished (no parrotfish, for example). In Southeast Asia, our reefs are also in this condition.

I was not alone in thinking so. Later when I got to Rangiroa, I saw how easy it was to catch a fish there. Big ones too. My host, a Pa’o’motu woman, told me that she had to move to Pape’ete for work once, and was shocked to find it so hard to fish there.

Algae at the reef edge

One day, I decided I would go to the edge of the lagoon. In the water I went, across the sand, and further on through the coral landscape. The lagoon became shallower, and the sound of the Pacific Ocean breaking on the reef grew louder. And then, suddenly, I came face to face with a bank of algae.

Braking suddenly, I backpedaled to avoid crashing through the algae. They were yellowish-brown, growing tall and thick. Swimming around, I discovered that the edge of the reef was forested by algae. I suppose the reef is very close to the water surface there. There’s plenty of sun to encourage algae to colonise the top of the reef.

Even within the coral portions, parts of the reef were overgrown by algae. I wouldn’t call it ‘smothered’, but there was a lot of it. As far as I can tell, the lagoon doesn’t seem polluted. But I guess it is a fairly contained body of water, which receives runoff from the river valleys and probably sewage discharges from Tahiti’s towns and villages. That might be enough nutrient load to favour the algae growth.

Exploring the algae forest

How interesting! I thought. Instead of lichen types of algae that look gunky on the rock, the algae here grow in thick stands that create their own complexity, similar to soft coral. I decided to examine them more closely, in case I could spot interesting marine life. Perhaps there might be seahorses.

But the algae forest is very shallow. I felt I could not swim over it without brushing the top. And suddenly it began to occur to me to wonder what else could be hiding in its camouflaging thickets.

It didn’t help that there was quite a bit of current here. I remember it pulled me alongside the reef. I guess the tide could be changing, and the lagoon was draining out to the ocean through a gap in the reef somewhere. So I decided to break away and swim back into the lagoon.

Near the boat, I surfaced. And the sky said, ia ora na!

Amanah (Stewardship)
Menanti detik penyu mengorek
Ikan yu naik merisik-risik
Si bapak borek anak pun rintik
Manusia baik dunia pun cantik. 
Dalam lautan penuhnya rezeki
Ciptaan Tuhan berpelbagaian
Bani Adam khalifah di bumi
Amanah Tuhan jangan lalaikan. 

Did you enjoy snorkelling with me in Tahiti? Pin this for inspiration!