Hairy Frogfish

August 31, 2015August 31, 2015 / Maarten De Brauwer / 12 Comments

It is clear that there is no shortage on weird critters in the ocean. Most of these happily bumble along the sea floor without attracting undue diver attention besides maybe the occasional researcher. But then there are those critters that stand out and are absolute favourites with divers and photographers. These superstars are on the wish-list of any diver who’s ever seen pictures of them. One of these absolute superstar critters, is the Hairy Frogfish.

Hairy Frogfish (Antennarius striatus) are one of those fish that make you stare and think “Why?”, “How?” or alternatively just “Huh?”. Besides being a Frogfish (which is reason enough to be interesting), they often are – as the name suggests – HAIRY. Yup, you’ve read that correct: a fish with hair on it. Or at least something resembling hair. To prove my point, here is a shot of a prime specimen:

Hairy Frogfish (Antenarius striatus)

In case you would be asking why, here’s is what we know: As many of the other critters I’ve written about, the main goal seems to be camouflage. This species seems to become hairy in areas with high filamentous algae growth, the hair mimics the algae and breaks up their body outline. However, Hairy Frogfish are not always hairy, they are relatively frequently seen without hair, but in that case they don’t always get recognised as “Hairy Frogfish”. As a matter of fact, their scientific name (Antennarius striatus) relates to the fact that they have stripes on their sides.

So seeing a hairy Antennarius striatus is as if you’d suddenly see a zebra covered in very long hairs….with a fishing rod growing out of its head….and a mouth so big you could fit an antelope in it…Let me just share this mental image to show you how VERY weird a hairy frogfish really is:

Terrestrial interpretation of a Hairy Frogfish..

On top of it, that nightmarish zebra would also be able to change colour. Not just to a kind of grey or brown, but nearly every colour in the rainbow! I have seen hairy frogfish being yellow, red, orange, black and white. The goal again is to blend in, so the white versions are often juveniles found in areas with many dead sea urchin-shells (which are white). This white version is usually not hairy to resemble the shell fragments even more closely. My favourite colour morph is the black version, which seem to get this colour when associated with living (black) sea urchins.

Black Hairy Frogfish

Hairy close-up

The other obvious question (How???) is harder to answer. There are a lot of theories around, but I could not find a single paper describing how the process happens. So we don’t really know, but the “hairs” seem to be filaments growing from the skin. To confuse things a bit, frogfish often also have real algae growing on them. This hairy appearance is not restricted to frogfish, but can also be seen in certain species of Scorpionfishes and Ghostpipefishes. The growth of it seems to be triggered by absence / presence of certain algae, but the exact details remain a mystery.

In the minds of many divers, the hairy frogfish is exclusively associated with world-class muck sites such as Lembeh Strait or Anilao. In reality, they are one of the most widespread species of frogfish. They can be found all the way to Perth and Sydney in Australia, but have also been seen in Brazil and Blue Heron Bridge in Florida. Genetic analysis do hint at the fact that these widespread Hairy Frogfishes might actually represent multiple species, plenty of room for some more research there….

Bad luck and How to find a frogfish

August 17, 2015August 17, 2015 / Maarten De Brauwer / 3 Comments

A few days ago, I prepared a blog post about a very interesting experiment we had started. It had everything to be cool (at least in my mind): interesting, sciency and a nerdy acronym to go with it! Luke and I were deploying SMURFs (Standard Monitoring Unit for Recruitment of Fish) to look at the habitat preference of baby fishes. The reason it did not get published, is the ocean. The night after successfully deploying the first 15 units, the waves picked up and destroyed all of our work… Marine biology fieldwork can be pretty amazing and it can be rather challenging as well. But that’s the beauty of the ocean: it’s unpredictable. Which can be frustrating at times, but can mean fantastic surprises as well.

Baby froggie

Which was proven once again when we found this very cute little baby Frogfish after assessing the damage to our equipment. We don’t know which species it is, since it was still tiny (less than 5mm). It was bright red, which would lead one to falsely believe they are easy to see on black sand. Think again! Next time you dive (or snorkel, or walk) over volcanic black sand, take a close look at the sand and you’ll notice there is a surprising amount of red grains in there. An unexpectedly efficient form of camouflage…

So how do you find a Frogfish? Or other cryptic critters for that matter? They have been evolving for millions of years to be invisible and most of them are very small, so spotting them is something that takes a while to learn. Here are a few tips to make it easier:

Movement: Your average Scorpionfish or Frogfish does not move very much, but every now and then they do. Whether it’s a small shifting of the fins, an eyeball that rolls to follow potential prey, or a full swim, our eyes are fantastic at spotting movement. So if you see an unexpected twitch or you think you might have imagined seeing something shift in the corner of your eye, investigate it!

Habitat: The critters I am investigating here are usually found on sand, but there are A LOT of different types of sand. Not just the type of sand, but also what’s on it, whether it’s algae, sponges, featherstars, logs, mooring blocks or anything else that offers a minor difference in structure. Certain species of frogfish (eg. Giant Frogfish) are nearly exclusively found on sponges, while other (eg. juvenile Hairy Frogfish) like to hang out in areas with a lot of shell fragments. Sand Divers (Trichonotus sp.) love very loose sand, while Thorny Seahorses seem to prefer coarse sand with plant debris. In this post I explain where to find different species of scorpionfishes.

Sand Diver (Trichonotus elegans)

Shape: Even with their amazing camouflage, fish will be fish, which means they have (most of) the parts normal fish have. These shapes can help you find them. The distinctive thick pectoral fin of Stonefish are one of the best ways to recognize them. Pygmy seahorses are tiny and hide in big seafans, but they use their tails to hold on, which is one the things you can look for to try and find them.

Stonefish are easiest to find by looking at their pectoral fins (orange in this individual)

Stonefish (Synanceia horrida) can be found by looking for their pectoral fins (orange in this individual)

Position: your own position makes a massive difference when trying to spot cryptobenthic fauna. If you are high above the sand, everything blends in, these species evolved to hide from most top-down predators. Get close and get low, if there is a slope, look up the slope instead of down, silhouettes often stand out this way.

Robust ghostpipefish (Solenostomus cyanopterus) mimick decaying leaf litter. Getting close and low makes finding them easier

Luck: In the end, good portion of luck can play a big role in finding that elusive critter you’re looking for. If anyone knows how to get better at this particular method of finding critters, please tell me!

Moving on

August 8, 2015August 8, 2015 / Maarten De Brauwer / 1 Comment

It has been a while since the last blog, mostly since we’ve spent the last week in places with very limited internet access. Here’s what we’ve been up to…

We left Lembeh last week. Having done 5 weeks worth of research in a muck divers’ paradise, it was to move on. During our time in Lembeh we spent more than 100 hours under water, collected nearly 100 sediment samples, did 70 transects, built a coral nursery, wrote a small fish-ID guide, took well over 2000 photos, collected dozens of surveys, talked to divers and diveguides and had an ab-so-lutely amazing time! You would think that after all of that diving over sand we might have been ready for a break. So the first thing we did when we left Critters@Lembeh, was head straight to another island for some more diving.

Part of the team in Critters@Lembeh

As it happens, good friends of Luke (Sophie and Simon) own Nomad Divers, a small dive resort on Bangka Island. Bangka is a 3 hour boatride away from Lembeh, and is a relatively un-explored dive destination. It is close to both Lembeh Strait and Bunaken, two of the world’s most renowned dive destinations, but it can hold its own between those bigshots. With loads of pygmy seahorses, great reefs, access to muck dive sites and even the occasional dugong, it’s not a bad place to dive 😉

Sophie, Luke, Max, Simon and me

Pygmy Seahorse (Hippocampus bargibanti)

You might have heard about Bangka recently, as it has been in dive and conservation-news a fair bit. A tin mine had been built illegally on the island a few years ago, and multiple NGO’s and divecentres have been fighting a long legal battle to close it down. With success, as last week the mining company lost the court case, effectively shutting down further mining. Which made our dives there even more enjoyable. Besides pygmy seahorses, we obviously had to check out the muck dives Bangka had to offer. We weren’t disappointed, as we found some beautiful little critters, some of which we hadn’t even seen in Lembeh.

Tarsier (or a Gremlin, not entirely sure)

Tarsier (or a Gremlin, I’m not entirely sure)

We said goodbye to Sophie, Simon and their (very cute) 3-months old son Max yesterday. Since we can’t dive before flying, we made decided to make the most of our forced terrestrial time, by visiting the Tangkoko National Park. The park is home to Crested macaques (endemic to Sulawesi!), Tarsiers and apparently a lot of birds as well. Which we only noticed by the swarms of bird watchers in the guesthouse where we were staying. If you think I am going overboard in my passion for marine critters, I invite you to come to Tangkoko and have a look at these bird-people, it’s rather entertaining really (and something of a terrestrial mirror for me as well). In any case, I guess we were not sophisticated enough for the bird watchers, but Luke and me did have a great time watching a large troop of macaques and 4 tiny little tarsiers.