Guestblog: Frogblogging – insights in the world of frogfishes

IMG_0737This month’s guestblog is written by Daniel Geary, the resident marine biologist at Atmosphere Resort in Dauin, Philippines. It’s safe to say that Daniel is very passionate AND knowledgeable about frogfishes. He’s been studying them for years in Dauin and even wrote (and teaches) a PADI speciality course on these awesome critters! In this blog he gives a taste of some of the many ways frogfish are fantastic and deserve a closer look.


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Longlure frogfish (Antennarius multiocellatus) from Florida

Frogfish. You have probably heard of them, and if you’re a diver you might have seen one or two before. You have definitely swam right past a few of them without knowing they were there. Although most of them have a face only a mother could love, behind this outer layer exists a well-adapted, expert fisherman with amazing camouflage capabilities. They are more than just a lazy, camouflaged blob that sometimes doesn’t change location for a year.

Frogfish are anglerfish, although they are what I call a shallow, less ugly version of anglerfish. They have a rod and a lure that they actively fish with when necessary. Their fins look like limbs that somewhat resemble those of a frog. They must inhale water though their mouth to then push it out of their gills which aids in locomotion. Frogfish are experts at changing color and can change color multiple times, usually to blend in with their surroundings. Normally a full color change takes about 2 weeks, but frogfish have been witnessed to change color in under ten seconds when disturbed by divers’ bubbles and needing to switch to a different coral.

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The same giant frogfish (Antennarius commersoni) changing colour in two weeks

There are around 50 species of frogfish, with a new species or two being described every few years. Frogfish can be found worldwide in tropical and subtropical waters (but not in the Mediterranean). Some species are only found at a handful of dive sites, others are only found in one country or continent. A handful of species are found in the majority of the warm water areas, but only the Sargassumfish is found worldwide. There have been a few occasions where Sargassumfish were found all the way up in the cold waters of Norway and Rhode Island – way out of their preferred habitat, but they live their lives floating in seaweed and/or other debris and are at the mercy of the ocean currents.

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Sargassum frogfish (Histrio histrio) often wash up on the shore of the Atmosphere housereef, when they do, they get released back into deeper water

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Painted frogfish (Antennarius pictus) using its lure to attract prey

Frogfish are ambush predators which is why they seem to be so lazy. The less they move, the better predators they can become due to algae, coral polyps, and any other organisms that use the frogfish as habitat. I call this being lazily efficient, or efficiently lazy. Frogfish will make minimal adjustments to their body positioning before they begin to lure prey, although sometimes the frogfish are so camouflaged that they don’t need to actively attract prey. Frogfish swallow their prey whole by opening their mouth and creating an instant vacuum since the volume of the mouth increases up to twelve times the original amount. This means frogfish can swallow their prey whole in six milliseconds. They feed on a variety of organisms, depending on where the frogfish lives. Generally they like small fish like cardinalfish, shrimps and crabs, and sometimes other frogfish. They can comfortably swallow prey that is their own size, and with a bit of effort they can swallow prey up to twice their size, although this can result in the death of the frogfish if the prey item is too large and gets stuck in their throat. Frogfish do not have many predators, but they are sometimes preyed on by moray eels, triggerfish, and lizardfish. Flounder will sometimes suck up juveniles from the sand and fishermen in the Philippines have been known to capture and eat Giant Frogfish.

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This giant frogfish (Antennarius commersoni) bit of more than it could chew and did not live to tell the tale. Photo taken at Apo Island

 

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Frogfish egg raft

Frogfish have been known to eat each other if they get too close, especially after failed mating attempts. A male will approach a female when she is bloated with eggs. He will do his best to show off for her, which includes expanding his fins to their maximum sizes, rapidly opening and closing his mouth, as well as violently shaking his body. At this point, the female either accepts him or tries to eat him. If accepted, he gets to stand next to the female, which is the frogfish equivalent of holding hands. Once he is ready to mate, he will start again with his flashy moves, but this time bouncing around the female. Sometimes he has to physically swim her off the substrate to mate, other times she is able to swim on her own. Once they are a meter or two above the substrate, the female releases her egg raft, causing her to spin rapidly. The male then fertilizes this egg raft, also spinning rapidly. Both the frogfish then return to the bottom as the eggs float off into the distance. The eggs will hatch a few days later and become tiny planktonic frogfish babies, which will continue to float for a month or two until they are big enough to settle in the substrate, change color, and begin their lives as adorable frogfish.

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A male (red) painted frogfish (Antennarius pictus) trying to convince the female (yellow) to mate

Stay tuned for more frogfish insights coming in December, where I’ll write about the history of frogfish research and describe a handful of frogfish species, including a potentially “new” species. Until then, keep an eye for frogfish on all your dives, especially if you’re in warm water.

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Fish nerds, critters, sharks and shirts

As I have written before, attending scientific conferences is an important aspect of working as a researcher. One of the benefits of being a marine scientist is that these conferences tend to take you to nice places (Hawaii for example), and this was proven once again at the 10th Indo-Pacific Fish Conference (IPFC), which just finished in Tahiti.

IMG_7936IPFC is the largest fish-focused conference in the Indo-Pacific region, and is held once every 4 years. This year was the 10th time it was organised, with more than 500 fish nerds scientists joining the fray. It is hard to explain to non-scientists just why these conferences (IPFC in particular) are such interesting events. They’re obviously good for learning about the newest research in your field, but it is also a great chance to catch up with old friends, or to meet the experienced researchers whose research you might know inside out, but have never actually met. It feels a bit like getting to mingle with the “celebrities” of the marine biology world. Besides celebrities and old friends, fish conferences are also THE BEST excuse in the world to whip out your finest/loudest fish themed shirts!

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Fish nerds rocking the fish-themed clothing at IPFC in Tahiti!

From a scientific point of view, some of my conference highlights were:

  • A big session with multiple talks dedicated to cryptobenthic fishes. It was fantastic to meet more people who study similar oddballs as I do, learn more about their research, and discuss important future research steps.
  • Hearing really bad news about how we are still overfishing most fish-stocks and how government subsidies make this problem much worse.
  • Then hearing good news on how well-managed marine protected areas have helped shark numbers in Australia recover from overfishing.
  • Plenty of new  and exciting developments in understanding the behaviour of fish larvae (I’m not even being ironic here, it’s awesome science, trust me!).
  • Learning more about why deep sea fishes look so weird and how their looks change with depth.
  • Thought-provoking questions on how to deal with oil and gas platforms in the sea after the wells run dry.
  • Finding out that parrotfish are a bit like hamsters, storing excess food in their cheeks while they’re feeding.
  • An important and super-interesting session that focused on women in marine science, which are (unfortunately) still underrepresented in our field.
  • The enormous kindness and willingness of experienced scientists to help and encourage the new generation.

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Squadron of blacktip reef sharks

Obviously while we were in Tahiti, we did more than just sit and talk about fish. We also went exploring to see what Tahiti had to offer and to find some actual fish. And oh boy, the fish we found!!! I might find a lot of very cool small critters for my research, but I rarely come across big sharks. During a shark dive just off Tahiti we saw 3 big tiger sharks, joined by a whole lot of other sharks for good measure. While tiger sharks are obviously not quite as interesting as small critters, they are impressive, awesome, and beautiful beasts! And while they get big (close to 4 meter), I did not feel worried about getting attacked at any point. They are undoubtedly top predators, but far from the monsters the media would like to make them out to be.

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Two tiger sharks and a blacktip reef shark

Besides sharks, we were also lucky to see humpback whales (from the boat), and went exploring on land. I’m sure you won’t be surprised if I tell you that Tahiti is a stunning place. Waterfalls all around, jungle, ocean, waves, super friendly people,… So you can imagine that this week I was mostly wandering around with a big grin on my face. On top of this, Tahiti is also a great place if you like tattoos, and I was very (very!) tempted to get a new one done here, but managed to stop myself. Only just though, so it’s probably a good thing that I am leaving tomorrow 😉

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Happy fish nerds exploring Tahiti’s beaches

So what next? I am writing up the last chapters of my PhD-thesis, so the search for new challenges (postdoctoral research!) is slowly getting started. There is more good news as well, an article on my biofluorescence research just got accepted in the journal Conservation Biology, so you can expect a new blog about that paper soon. But before that, a new guestblog is coming up that delves deep into the world of frogfishes…

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