On the origin of muck diving

The last 3 years of my life have been dedicated to intensely studying critters and socio-economics related to “muck diving”. While this is a relatively common term in the scuba diving world, the vast majority of people haven’t got a clue what muck diving is. I can’t count the number of times people at conferences, meetings, drinks, etc. have gone: “You study what diving???”. Marine scientists seem to prefer hearing “Cryptobenthic fish assemblages on tropical sublittoral soft sediment habitats” than “Critters in the muck”. Each to its own I guess?


Classic muck diving scene (Photo: Dragos Dumitrescu)

It’s not just scientists who are confused, a lot of divers have questions about muck, or at the very least are curious about how it started and where the name came from, so I decided to dig a bit deeper and find out some interesting facts about the origins of muck diving. If you have never heard of muck diving or just aren’t sure what it is, here is how I defined it in my last paper:

“Scuba diving in soft sediment habitats with limited landscape features, with
the explicit goal to observe or photograph rare, unusual, or cryptic species that are seldom seen on coral reefs.”

Or easier: Diving on sand/mud/rubble to find cool animals you don’t see on normal divesites. The word “muck” means either “Dirt, rubbish, or waste matter” or even worse “Farmyard manure, widely used as fertilizer”. In British English it is also used for “Something regarded as distasteful, unpleasant, or of poor quality”. I would guess that it’s the combination of the first and last meanings that inspired the people who started this type of diving.

Muck diving in its current shape has its origins in Milne Bay, Papua New Guinea. On a site called Dinah’s beach,  where Bob Halstead decided to try to do a dive on the site where their boat (the MV Telita) was anchored. The divers were skeptical at first as the site was mostly sand and did not look very appealing, but after discovering tonnes of creatures they had never seen before they were sold and muck diving was born. From its origins in Papua New Guinea, muck diving caught on and became popular across the world, but no place is as well known for muck diving as Lembeh Strait in Indonesia.

Map Milne Bay

Milne Bay, Papua New Guinea, where it all started

It is clear why Lembeh is famous with muck divers, as it really is a great place to dive and find some of the world’s most amazing critters. But how did muck diving in Lembeh kick off? What many people don’t know, is that Lembeh’s origin-story as the world’s most famous muck dive destination is pretty grim. The first resort in Lembeh (Kungkungan Bay Resort) was built in 1994, but the owners did not build their resort with critters in mind….

Back in those days, Lembeh was one of the best sites in the region to watch the big stuff. The plankton-rich waters of Lembeh Strait attracted scores of manta rays, dolphins, sharks,… Until 1996, when mankind showed just how destructive it could be. In March of that year, foreign fishermen came in and (illegally) installed the “Curtains of death”. These were huge nets, placed across the migratory routes of the large fish near Lembeh Strait. The nets were deadly efficient, during the 11 months they were used they caught:

  • 1424 manta rays
  • 577 pilot whales
  • 18 whales
  • 257 dolphins
  • 326 sharks (including whale sharks)
  • 84 turtles
  • many other animals including turtles and marlins

The original article about the curtains of death can’t be found online, but if you are interested, send me an email and I can send a copy. If you want to know more about destructive fishing in Indonesia, this is an interesting source start with.


Peaceful Lembeh Strait has a turbulent history

The numbers are staggering, and for the few tourism operators in the area it must have been quite a shock. Until they discovered that Lembeh had much more to offer than just the big stuff. While there are no records of it, the story goes that muck diving in the area only properly got started when people started looking down at the sand instead of up at the manta rays. It makes me wonder what the area would have looked liked otherwise, and if muck diving would exist in the way it does now…

As it is now, muck diving is big, it attracts divers from across the globe and new critter hot spots keep on being discovered far beyond from where it all started. It’s exciting to think about how much more we will discover in the future! For me, one of the changes I would like to see, is the actual term “muck diving”. The name coined by Bob Halstead stuck, but I think most people in the diving (and academic) world agree that it isn’t really the most inviting name. I’d like to hear your suggestions (below in comments) on more suitable names for this type of diving and the divers doing it. If I get enough suggestions, I’ll organise a poll later to see what is preferred by divers around the world!


It’s all about finding the small stuff – baby Painted frogfish (Antennarius pictus)

PS: Originally I wanted the full title of this blog to be “On the origin of muck diving by Means of Photographer Selection, or the Preservation of Favoured divesites in the search for Critters”. But the long title might have put off those readers who didn’t immediately get the very nerdy biology pun.


What is a species?

As promised in a previous blogpost, it is time to get into another hotly debated topic in biology that most non-biologists wouldn’t even think was an issue at all. This is a big one, as it underpins pretty much all biology: “What is a species?”. I would argue that this question needs two important additional questions: “Why does it matter?” and “To whom does it matter?”. Since I am only human and like postponing difficult tasks at hand, let’s start with the follow-up questions.

speciesTo whom does it matter that we are capable of telling one species from another? Besides looking like a smart cookie when telling your fellow divers/birdwatchers/plant enthusiasts which species you’ve just seen, it doesn’t matter very much to be honest. We are no longer hunter-gatherers, so being able to tell which species you can eat, and which ones will will eat/kill you, doesn’t matter that much anymore. In other words, the discussion in the rest of this blog is mostly an issue for taxonomists, but it gives an interesting insight in how simple concepts can be quite complicated when you look closer.

Why does it matter then? For two reasons:

  1. People in general and scientists in particular like putting labels on objects around them, it helps us structure and understand the world we see.
  2. Being able to tell two species apart that look very similar can have big consequences for conservation action: Two birds/fish/plant might look similar, but they could be different species, one of which reasonably common, but the other one rare and on the brink of going extinct. If we don’t realise they are different, we might lose that species.

A logical follow-up question (in my mind) would be: “what does it matter if one species that looks a lot like the next goes extinct?”. This is a valid question, but would require a long (and interesting) scientific and philosophical discussion.


Struggling to define what a species is? Don’t worry, so did Charles Darwin (photo source: www.brainpickings.org)

Back to the species concept, which seems obvious, but really is not. The question has been asked for centuries by many renowned scientists. Two of which were none other than Charles Darwin and Alfred Russel Wallace. It could even be claimed that this question is what eventually led to the theory of evolution, which essentially tries to explain how different species come into existence. It is obvious that you need to know what a species is before you can answer that question. Sometimes it is easy: the majority of people can tell the difference between a cat and a dog, but it becomes a lot more difficult when species look very similar. Try asking a marine biologist what the difference is between a Slingjaw wrasse (Epibulus insidiator) and a Latent slingjaw wrasse (Epibulus brevis), or between a Thin Ghostpipefish (Solenostomus leptosoma) and a Robust Ghostpipefish (Solenostomus cyanopterus). Go on, give it a go, it’ll be fun to see them struggle! (Smart-ass tip: a spot on the dorsal fin & smaller adult size / No difference, they are most likely the same species).


They might look different, but are the same species. Photo source: www.dogguide.net

The problem is how do you define a species? At what point is an individual that looks different than “the norm” a different species, rather than just natural variation? Dogs can look as different as Danish dogs and (rats) Chihuahuas but are all the same species. Compared to those two, lions and tigers look much more alike, yet they are very different species. The classic definition of a species (if they cannot have fertile offspring they are different species) works in most cases. Lion + Tiger = Liger, but ligers are infertile. I don’t know what Danish dog + Chihuahua would look like and I wouldn’t get ethics approval from my university to test it, but presumably the result would be a fertile dog.

So far the normal situation, but what happens when different species mate and have fertile offspring (hybrids)? This is surprisingly common in the ocean. Hybridising fish are not that rare if you know what to look for. I have personally seen it in Clownfish and Surgeonfish and almost certainly in Frogfish and Ghostpipefish. But is has also been recorded in groupers, manta rays, butterflyfish, angelfish and wrasses.


Hybridising surgeonfish: r: Acanthurus lineatus s: Acanthurus sohal t: A. lineatus x A. Sohal hybrid (Source)

In this case, can we say the parents are different species because they look different, behave differently, and typically live in different regions? Or are they a single, highly variable species, the way dogs are? Traditional taxonomy focused on what species looked like, would say they are different species, but not everyone agrees with this. A recent example from the pygmy seahorse world: Hippocampus severnsi and Hippocampus pontohi were described as two different species. However, new (yet unpublished) research shows that they are genetically identical, so the name H. severnsi was removed and they are now all called H. pontohi. I’d imagine much to the annoyance of Mike Severns, who no longer has a cool animal with his name on it.

Is genetics the solution to the problem? Depends on who you ask. Geneticists tend to say yes, old-school taxonomists tend to be a bit less convinced. Each side has very valid arguments, one of which is how genetically different do individuals have to be before they are considered different species (sound familiar?). Different cut-offs have been proposed, but as far as I know, there is no real consensus (please correct me if I am wrong geneticist-readers). Another serious issue is how to classify small life forms like microbes, this article has a great summary on that if you are interested.

If you think this is getting too complicated, it might be best not to become an evolutionary biologist or taxonomist, because things actually get a lot more complicated than what I described. Suffice to say, for biologists the term “species” is still not a clearly defined concept. But luckily for non-specialists, the essence of the debate is about such fine details that it really shouldn’t be keep you up at night.

New publication: Big bucks for small critters

One of the most important chapters of my research has recently been published in the journal Marine Policy. The paper explains that scuba dive tourism focused on small critters (“muck diving”) has a very high value and how muck diving can be a sustainable alternative to more destructive uses of the environment. This is the link to the paper, but since it is behind a paywall, is rather detailed and perhaps a bit to dry for those of you who are not economists, below is a summary that is easier to digest.


A typical muck diving scene: a sandy bottom with few defining features. In the foreground an Estuary seahorse (Hippocampus kuda) holding on to algae (Photo by Dragos Dumitrescu).

If you don’t know what muck diving is, I invite you to have a look through this site to get a feel for it. But in short: muck diving is scuba diving in sandy areas, usually without coral or other landscape features. The goal is to find weird critters (like flamboyant cuttlefish or hairy frogfish)  that you’d rarely see on normal dive sites. It is very popular in places like Lembeh Strait and Dauin in Southeast Asia, but it is done by divers and photographers all over the world.

Typical for muck diving is that the people doing it are very experienced, with an average of 580 logged dives. Most of them (73.5%) use underwater cameras, often the expensive dSLR cameras, to photograph all the weirdness down there. Many of the divers are well-educated and have a high yearly incomes. Importantly, most divers would be willing to pay for marine conservation if it benefits the species they come to see.

So what does it matter if some fanatic divers like to spend their holidays rooting through the sand instead of cruising by pretty coral reefs? Well, for starters, those fanatic divers spend a combined whopping $152 million per year in Indonesia and Philippines alone. The real value is probably much higher, as this estimate is only for dive centres that specialise in muck diving, and does not include liveaboards or more general dive centres that visit muck dive sites. The real value could be over $200 million per year! Also bear in mind that this number is for Indonesia and Philippines only, it does not include muck dive tourism in Malaysia, Papua New Guinea, or the rest of the world. With more than 100,000 divers visiting Indonesia and the Philippines to go muck diving, you would expect to get the attention of people managing tourism or ocean resources. Especially since many of the divers said they would not have visited the region, or even the country, if they could not muck dive.


Diver and Ornate ghostpipefish (Solenostomus paradoxus) in Dauin, Philippines

While these numbers might not change anything in your life, they make a huge difference for the thousands of local people that work in this branch of the dive industry. Muck diving is often done in remote locations with limited other forms of income besides fishing. Working as a dive guide and looking at fish is not only more sustainable than catching fish, it also pays a lot better. Roughly $51 million is paid in wages to the local staff working in muck dive tourism annually, and dive guides can earn nearly 3 times more than the minimum wages in the area….

Just stop and think about that for a minute. Imagine the minimum wage in your own country, now triple it. Got the number? OK, now imagine this choice: you can either make that amount by showing cool animals to divers, or you can work your ass off in a factory or risk your life fishing for a third of that amount. Small wonder that many people prefer the first choice, which is great news for marine life in the area, because it means less people fishing and more people trying to protect this valuable source of income.


The future generation of muck dive guides? Not without a healthy ocean (Photo: Luke Gordon)

That is what it comes down to in the end, protecting these extremely interesting and valuable ecosystems. Make no mistake, muck sites can be threatened as well. Coral reefs might bleach because of climate change, mangroves might be cut to make space for shrimp ponds and seagrass might be dredged to mine for sand, but sandy habitats could face other risks with equally bad consequences. All the habitats above receive far more research and conservation attention than the “barren” sandy sites in the tropics. If this paper proves anything, it is that soft sediment habitats have a very high value, and that it should get more attention to avoid loosing amazing biodiversity and the subsequent loss of income for the thousands of people that depend on it.

And that does not even consider loosing that feeling of pure joy when you finally find a critter you’ve dreamed of seeing for years 😉

Luke_Snoot_Black Hairy

Muck diving scene: a diver (the science hobbit) taking a picture of a frogfish (black Hairy frogfish – Antennarius striatus)

Fluo time

If this isn’t the first time you’ve read this blog, you probably know I am interested in the phenomenon of biofluorescence. I’ve previously talked written about what it is and what it might be used for. In the near future I’ll be tell you all about the details what I was actually doing. But I realized I haven’t shared any pictures recently that show just how beautiful and otherworldly it can be. So here is a random selection of fluo shots I took over the last two years. Enjoy!


A bubble snail (Hydatina physis) photographed in Lembeh Strait, Indonesia



Thorny seahorse (Hippocampus histrix) in Bima Bay, Indonesia



West Australian Seahorse (Hippocampus subelongatus) in Perth, Australia



Amazing coral in Raja Ampat, Indonesia



Reptilian Snake Eel (Brachysomophis henshawi) in Amed, Indonesia



Lizardfish (Synodus sp.) in Lembeh Strait, Indonesia



Cockatoo Waspfish (Ablabys sp.) in Lembeh Strait, Indonesia



Sea spider (Pycnogonid sp.) in Tulamben, Indonesia



Painted frogfish (Antennarius pictus) in Lembeh Strait, Indonesia



Juvenile Painted frogfish (Antennarius pictus) in Dauin, Philippines)



Barred moray (Echidna polyzona) in Nusa Kode, Indonesia