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Underwater Highlights of Lembeh Strait

By any measure, Lembeh Strait in Indonesia is one of the world's great epicenters of weirdness.   This striped frogfish is just one of many examples of the strange critters to be found in this stretch of shoreline between the northern coast of Sulawesi and Lembeh Island.   The frogfish doesn't do much swimming like a regular fish, instead it walks along on the sea floor.   It's an ambush predator, waiting for something tasty to come along, attracted by the lure which you see on top of its head, which is at the end of a little fishing rod which the frogfish twitches around in front of its mouth.

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All frogfishes have a lure, which is why they're also called angler fishes.   Many of them do a very good imitation of a marine sponge, all the better to fool their unsuspecting prey within range.   They have an extraordinary ability to change their color to match their surroundings, which unfortunately also makes them rather difficult to identify - the striped angler above is the only one of about five or six species which I was able to confidently name.

Frogfishes are only the beginning of the strangeness in this place.   This dragon sea moth or little dragonfish also avoids swimming around, instead walking along the bottom in close proximity to its mate.   It has a snout which would make any mother proud and its cryptic coloration makes it blend very well into the background, just in case anything is silly enough to eat such a bony little fish.   When they accumulate too many parasites and other baggage they can shed their whole skin in one move by rapidly leaping forwards.

Bony is one thing, but spiny is something else again!   The thornback cowfish does swim like a regular fish, but its boxy shape and the five spines strategically located around its body provide it with a lot of protection, and the two horns on its head even provide it with its name.   If the thorns aren't enough then it can even release a toxin to put off its attacker.   Males produce a high-pitched hum when mating, which apparently doesn't put off the females too much - maybe they even enjoy being serenaded in this way.   Of course with a mouth like this, there's no way the cowfish can actually sing or even moo!

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An oddly shaped mouth is also a characteristic of this next critter, a thorny seahorse.   This family of fishes isn't very common at all, in fact Lembeh Strait is the only place I've ever seen them, and not just this species but also common seahorses and the remarkable pygmy seahorse, which is smaller than this one's long nose.   Sea horses are so well known, including unusual behavior like the males brooding the eggs, that it's easy to forget what an unusual animal this is.

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Sea horses belong to the same family as pipefish, and Lembeh Strait is a great place to see those, too.   Like their cousins, pipefishes have mouths at the end of their long snouts, which they use to suck up tiny shrimps and other crustaceans.   The males also carry the eggs, but whereas seahorses have pouches on their bellies, the pipefishes stick the eggs on a patch on the outside.   This pair of ornate ghost pipefishes has changed its coloration to match the crinoids it's living amongst, but I also saw individuals of the same species which were black and brown to match their environment.

But the grand prize for camouflage goes to the halimeda ghost pipefish, named for the green leafy halimeda algae it lives amongst.

This fish has not only matched the color of its surroundings, its lobed fins have even taken on the same shape as the leaves of the algae.

They can even change their color to match dead or dying grey leaves and, if you look straight below this green individual then you'll see that its mate is a totally different dull brown hue.

These guys are so cryptic and uncommon that they were only scientifically described as recently as 2002.

This longsnout flathead is a lot bigger than the halimeda ghosts pipefishes and isn't anywhere near as rare, but it's interesting nevertheless.   The different species of flatheads are also called crocodilefishes and, with a shape like this, it's easy to guess that they spend most of their time lying on the sea floor.

Even as a child in New Zealand I was familiar with this fish, though in a very different context to this.   It's an oriental flying gurnard, which I saw mostly as fillets in the local fish shop, waiting to be dipped in batter and fried.   I certainly never saw it like this, crawling along the bottom like so many of the other inhabitants of this place, and flaring its huge pectoral fins when disturbed.

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Some of the fish in Lembeh Strait won't even settle for lying down on the bottom, they insist on actually digging themselves in!

This is a whitemargin stargazer which swam past me as I was photographing a snake eel on a night dive.

Neither of these two creatures is commonly seen swimming in the open, but it was obvious that when this guy came past it was "goodbye snake eel, hello stargazer", since the stargazer is such an extraordinary looking animal, and much less common than the snake eels.   I had some more luck when it decided to bury itself just a few meters away from where I first saw it.

Stargazers get their name both from being nocturnal and from their habit of looking up, which is pretty much a necessity when the rest of their rather large body is buried in the sand.

Like the anglerfishes, stargazers also have a lure, which you can see just in front of its mouth.

You can see a couple of spines at the broadest part of this fish's back.   Not only are these spines hard and sharp, they're also toxic enough to cause a serious wound in any diver stupid enough to provoke the stargazer.   On top of that, they also have an electric organ which is apparently defensive and can generate around 50 volts.

Here's one of Lembeh Strait's most famous inhabitants, a very rare paddle-flap scorpionfish, often referred to by its genus name of Rhinopias.   All of the Rhinopias species have upturned noses like this and eyes on the ends of short stalks.   At any one time there are probably a couple of hundred divers staying in the dive resorts along the Straits, and all of them want to see this individual, which probably makes it one of the most photographed wild animals in all the world.

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Along with this one!   Let's see, upturned nose and eyes on the end of short stalks - it's another Rhinopias!   This one is named the lacey scorpionfish after the lace-like patterns which cover its entire body.   Not only are these two different Rhinopias species both in Lembeh Strait, but they actually hang around within a few meters of each other, apparently enjoying each other's company.   Most divers around here are photographers, so this arrangement is very convenient for the humans, and the two scorpionfish seem to have learned to tolerate all of the papparazzi who periodically descend on them from the world above, flashing their lights repeatedly and sometimes, unfortunately, moving both of the fish together for that "perfect" shot.

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This oddity is another scorpionfish and yet another fish that prefers walking to swimming!   Because of the powerful venom in their fin spines, scorpionfishes are one of the most feared families of animals in the ocean; this leaf scorpionfish is much smaller than the two Rhinopias species above, but it's actually the only one of the three which is considered dangerous.    However, like all other scorpionfishes it isn't aggressive, in fact it gets its name from its habit of slowly rocking from side to side in the current, pretending that it's a leaf, just like the cockatoo waspfish which looks very similar and also lives here.

The scorpionfish family also includes stonefish like this one, which is most often called a spiny devil, though I prefer the alternative name "bearded ghoul", for obvious reasons!   It has an upturned nose and eyes on stalks, but it's not a Rhinopias.   As you can see from this photo, it has several "legs" which are actually unattached spines from its pectoral fins, and these allow it to.... walk along the bottom!   Its venom can be fatal to anyone who doesn't notice it when diving, or pulling it out of a fishing net.   You can see from all of the gravel on top of this one that this species often buries itself while waiting for its prey.

Lionfishes like this one also belong to the scorpionfish family, and they're another highly toxic group of fishes.   This shortfin lionfish is one of the smallest members of this distinctive group of fishes, which leads to its alternative name of "dwarf lionfish".   Almost all lionfish have a red or brown color scheme with white stripes, but shortfin lionfish are usually reddish brown with yellow.   Very occasionally bright yellow individuals like this one are found, and in fact I saw four or five like this during my week long dive trip.   This one made its way onto this page by very thoughtfully posing on this small coral head with those picturesque sea squirts right alongside!

Moray eels are another family which induce a lot of fear, but with far less cause than the scorpionfish family.   Although they have large, sharp teeth, you'd have to corner a moray and provoke it pretty badly to make it bite you.   Usually you don't see them out in the open like this, but I found this minor moray eel while on a night dive, when it felt safe enough to venture forth.   This is the first time I've seen this species, but there were also fimbriated, snowflake and white-eyed morays around, as well as a couple of other species I couldn't identify.

Here's a black-finned snake eel, along with a friend.   As I mentioned in the section on the stargazer, snake eels aren't usually found in the open, instead they bury themselves in the sea floor and wait for something tasty to pass along.   Apparently cleaner shrimps aren't on the menu, because it's very common to see them along with this species of snake eel.   In spite of their scary appearance, they're also not dangerous to people.

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Believe it or not, this cute critter is another moray eel, usually called a ribbon eel, but occasionally called a leaf-nosed moray because of the way the ends of its nostrils flare out.

People used to believe that there were three species of ribbon eel, one black, one blue and yellow like this individual, and another which is entirely yellow.

After a lot of investigation it was learned that there is only one species, the black ones being juvenile males, the attractive blue and yellow ones being adult males and the yellow ones being females.   And no, there are no juvenile female ribbon eels, which begs the question:  What the heck???

Here's how it work:   when it grows up the juvenile males change color and become adult males and then, when it's sick of that, the adult male abruptly changes sex and becomes female and yellow!   It's the only moray eel which pulls this sort of trick, though quite a few other fish like the ever popular clownfish do the same thing.   Yes, you heard me right - Nemo's mom was actually a male before Nemo's dad met her and married her!

Ribbon eels aren't that rare per se, but for some reason females are very uncommon, so much so that I've never seen one.

By now you should have noticed that there's a distinct lack of coral and pretty fish at Lembeh.   That's because this is the world capital of muck diving, which is all about diving where the sea floor is composed of sand, gravel or rubble instead of coral reefs.   But amid all of the weirdness there's still plenty of attractive animals like the ribbon eel, and there are even small areas of coral with the usual populations of butterflyfishes and other tropical beauties.   And then there are anemones scattered around with the ever-popular clownfishes and specialties like this Banggai cardinalfish, which was introduced here from the nearby Banggai islands.

OK, enough of this cuteness!   Let's segue back from cute to weird with the help of this sweet pair of red-barred shrimp gobies, who live in a most unconventional relationship with these shrimps.   Actually there are many types of shrimp gobies, all of which live with shrimps, but it's not common to see two gobies sharing the same hole with two shrimps.   The gobies keep lookout while the shrimps keep house; the shrimps have very poor eyesight so they keep their antennae in contact with the gobies at all times, who flick their tails at the first sign of trouble and retreat into the shared accomodation when things look really hairy.

There are lots of interesting and attractive shrimps here, including mantis shrimps, harlequin shrimps and this emperor shrimp, which can be found hitchhiking on sea slugs, sea stars, or on lion's paw sea cucumbers like this one.

There are plenty of other interesting crustaceans here, like this spotted porcelain crab.   It has only three pairs of walking legs and it also has long antennae, which give away the fact that it isn't a true crab, instead it's more closely related to squat lobsters.   It feeds by waving around a pair of feathery structures held near its mouth, using them like baskets to strain plankton out of the water.

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This is a red-spotted box crab walking around at night on its spindly legs, an uncommon sight since they usually bury themselves with only their eyes protruding.   The different types of box crab are also referred to as "shame-faced crabs" because of the way they hold their huge claws in front of themselves.


The white-spotted hermit crab is another nocturnal denizen of the deep and once again the antennae are a giveaway that it's not a true crab.   This is one of the largest of all hermit crabs, reaching up to 30 centimeters in length and has a voracious appetite, eating worms, molluscs, fish and algae.   The left claw is larger than the right, and is a formidable weapon, being used even against octopuses, which normally feed on crustaceans!

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Beauty can be found in the strangest places, like the brilliant colors and patterns on this blue-spotted urchin.   Pretty to look at, but you'd better not touch it!

When underwater photographers want to find something beautiful, they go looking for slugs!   Sea slugs like this Mexichromis multituberculata have vibrant colors and patterns, and sometimes an interesting shape as well.   This one is even doing a passable imitation of a reindeer - its left rhinopore, the purple structure on the right side of the photo, is branched, which is very unusual and maybe indicates an injury.   This sea slug is doing something else interesting, too - laying eggs!   You can see the flat ribbon of eggs coming out of its side, it'll keep going until it's laid a complete spiral of eggs.

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I saw about 30 different species of sea slugs during my time here and even a few snails, too, like this ivory cone shell.   It might look pretty, and maybe even comical with those two eyes on stalks and the long extended mouth like an elephant's trunk, but this large family of snails is infamous for the deadliness of their venom.   As soon as the snail detects a small fish, a predator, or a diver foolish enough to pick it up, it points its mouth towards its victim and shoots a venom-packed harpoon into its flesh.

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The dive site called Nudi Retreat is famous for another mollusc, commonly called the "electric clam".   It's a brilliant red color with lots of tentacles, but its most extraordinary feature is what looks like rapid pulses of bright light constantly rippling around the edges of its mantle.   It's really something you need to see on video, but this photo does show some of the bright patches in action.

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Most people don't realize it, but cephalopods like octopuses, squid and this cuttlefish are also molluscs, though obviously much more mobile and without a shell!   Cuttlefish can put on their own extraordinary rapid-fire displays of color and pattern, and they can even change the textures of their body, as this one is doing by raising spikes along its back and sides.   This group of animals is considered the most intelligent of all of the invertebrates, and it's quite common to have one warily eyeing you while it decides whether you're a threat.

Lembeh is also home to two famous species of octopus, the mimic octopus and wonderpus, which is shown here.   They look similar, both have stripes and eyes on the ends of stalks, but I think that wonderpus has the edge because of its attractive chocolate brown coloration, compared to the darker mimic, and it also has one of the coolest scientific names of any animal - Wunderpus photogenicus.   Both species use their patterns to imitate other animals like banded sea snakes and lionfishes, but the mimic earns its name by also imitating flounders and a variety of other animals.

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