Guest blog: Big brother is watching – Spying on the secret lives of endangered seahorses

Louw_CroppedIt’s time for a new guestblog, this one is by the amazing Louw Claassens. Louw is a South-African marine scientist at the Knysna Basin Project and a member of the IUCN Seahorse specialist group. She studies one of the world’s most endangered seahorses, part of her work involves studying their behaviour, which recently resulted in a very interesting publication (go check it out!). In this guestblog she gives you the most important findings of that paper and shares some fantastic video footage. Enjoy!

A big part of ecological research is based on observations – where do animals occur, what do they eat, what do they do. Some of these questions can be answered by using standard scientific methods e.g. a population survey can tell you where animals occur (although why is a whole other kettle of fish!). The tricky part sets in when you want to find out what an animal is doing. Conventionally, this entails going to the animal in question and watching it (sounds pretty simple, right?!). But it is here where observational effect (the act of observing has an effect on behaviour) and observational bias (researcher bias as to expected behaviour) creeps in.


I spy with my little…GoPro? (Photo: Louw Claassens)

One of the 21st century solutions to these observational problems, is using cameras to study animals, and we are now even able to use cameras to study animals under water (thank goodness for relatively cheap action cameras such as GoPro’s!). Most fish research uses cameras to look at fish diversity, abundance, and habitat use – with limited work on actual fish behaviour. One of the reasons for this is probably owing to the highly mobile nature of most fish species.

So, is there a place for action cameras in fish behavioural research?

We focused on seahorses to answer this question. The conventional way to study seahorse behaviour entails getting in the water and watching the seahorse go about its business. Or, getting some seahorses and conducting observational research in the lab. The first method is problematic owing to two reasons: 1) Observer effect (the seahorse might act differently when you are watching it), and 2) seahorses move quite slowly most of the time, so detecting a behavioral pattern is quite difficult. Not even to mention the costs and time involved in doing this. The latter method might make sense, but it is well known that animal behaviour in captivity is rarely authentic.

H. capensis_cropped

A very well camouflaged Knysna seahorse (Hippocampus capensis) (Photo: Louw Claassens)

Our aim was to test the efficacy of using video cameras to study the natural behaviour of a seahorse, and we had the perfect opportunity to do this! During a recent population survey of the endangered Knysna seahorse (Hippocampus capensis) in the Knysna estuary (South Africa) we found a stable population within a residential marina estate. The seahorses were found to use artificial Reno mattresses (wire cages filled with rocks). We had the seahorses, we had a relatively protected area to deploy cameras, and we had a sturdy structure to attach the cameras to.

In the first instance, we wanted to see if seahorse behaviour changed throughout the day e.g. between the morning, midday and afternoon. To add to this, we had an opportunity to see what happens to seahorse behaviour during the busy December holiday season. To do this, we used boat noise as a potential stressor (as occupancy of the residential marina estate increases from ~30 % to 100 % over the holiday period).

Video: Aggressive behaviour in the Knysna seahorse (Hippocampus capensis) – main action starts at 0:45.

But first we had to see if cameras successfully captured seahorse behaviour and if they could be used in behavioural assessments. We conducted a short trial period to test this, and found that 49 % of footage recorded contained seahorses. Using this data, we created an ethogram (a catalogue or table of all the different kinds of behaviour or activity observed in an animal) for H. capensis:

  • Feeding: the seahorse is actively searching for prey animals.
  • Irritation: identified by increased clicking and tail adjustments.
  • Moving from holdfast to holdfast: seahorse moves around without any feeding behaviour in-between.
  • Interaction: interaction behaviour can either be between a male and female as part of courting or between seahorses of the same sex and might entail aggression.
  • Stationary: seahorse remains completely still.

Video: Knysna seahorse (Hippocampus capensis) feeding

The next step was to deploy the cameras throughout the day (morning, midday and afternoon) and across the longer time periods (Pre-holiday, Holiday and Post-Holiday). To assess behaviour we used 10-min video sections as a sample and timed all observed behaviour for a single focal animal during the sample.

We recorded hours of footage, of which 57 hours contained suitable footage of seahorse behaviour. Seahorses spent 82 % of their time feeding and we noted courting behaviour exclusively in the morning. This courting behaviour entailed grasping of the female’s tail by the male in an attempt to position himself face to face with the female, followed by swaying movements. We also found that seahorses were more visible and fed more during the morning. There were no differences between the behaviour of males and females.

Graphic footage! Video of a cormorant catching a seahorse (H. capensis)

We observed quite a few cuttlefish, rays and cormorants, but only noted predation by the latter (check out the video above!). Seahorses were also observed happily living side by side with octopus, although octopus are known to eat seahorses in Australia. We also noted some other curious fish, like our temperate butterfly fish (Chaetodon marleyi) (video below) – can you spot the seahorse?

A cold water butterfly fish (Chaetodon marleyi) checking out Louw’s GoPro setup

When we looked at behavioural changes across the longer-term periods, we noted a decrease in visibility and feeding activity of the focal seahorse, with an increase in irritation behaviour, during the holiday period. No courting behaviour was noted during the holiday period – which is a bit concerning, seeing that this species breeding season is from September to March.  Feeding activity and seahorse visibility increased again during the post-holiday period.

So, what does all this tell us? Action cameras are pretty useful in studying natural behaviour of seahorses. Recorded footage can be watched on fast-forward mode which enables a clear view of the behavioural pattern of the animal (something that is quite difficult to see whilst diving, as these guys move so slowly). For H. capensis, it was the first time that natural behaviour was studied, and we gained some valuable information with regards to feeding and interaction behaviour. In addition, it seems that boat noise has a negative effect on the natural behaviour of this species – an aspect which does need further research (preferably, a controlled experimental approach is needed here, to control the vast number of confounding factors that might have played a role!). The use of cameras in natural seagrass habitat also needs to be tested, as visibility might be problematic in dense vegetation.

In the past, the world of underwater research was exclusively meant for the eyes of the researcher/diver. Now, we are able to bring what we experience to the surface and to the lay person. And perhaps the real power of doing this is to create and instill that love and passion for the underwater world that all divers and water lovers have, in all people. I mean, who cannot fall in love with two seahorses doing their morning courting dance?

The secret sex lives of seahorses: mating dance of the Knysna seahorse

Photo Story: Hidden Treasures Amongst the Muck – Guestblog by Luke Gordon


Time to kick of December with a new guestblog, this one by none other than my good friend and science hobbit Luke Gordon! Luke is a very talented photographer whom I’ve been having ocean adventures with for many years. He is currently based in Canada, but continues his photography work there. Increasingly he uses his art as more than mere beautiful pictures, but instead uses it to tell important stories about ocean conservation issues. You really should have a look at his site, but until you do, here is an introduction to his most recent story.

Diverting the majority of my photography work towards conservation photo journalism has been an incredibly rewarding experience so far. I am very lucky to have met various people & organisations over the years which has now allowed me to get up close and personal to certain issues such as, establishing sustainable fisheries in Fiji, and now looking at salmon enhancement projects in British Columbia, (and of course Maarten, the first person worldwide to be dedicating a PhD solely to the soft sediment world & the creatures living there).


A ‘barren habitat’ could not be further from the truth, life here as evolved in the most intricate of ways, mimicry is the name of the game on the muck slopes. Species such as this Giant Frogfish (Antennarius commersoni) have evolved near perfect mimicry of sponges as they sit in wait for unsuspecting prey.

The critters of the muck for me, and I am sure for the large majority of photographers who have experienced this world, are the perfect definition of evolution and beauty of the natural world. Everything about this underwater paradise captivates me. From the story of its discovery to the most elusive of its organisms, muck is a magical world.

Let us start at the discovery, muck was discovered by chance by Bob Halstead, a man credited for pioneering the liveaboard industry and diving in Papua New Guinea, the story goes that whilst on a liveaboard in PNG the boat had moored up in Milne Bay for the night where it was calm, Bob Halstead still wanted to go for a night dive and despite the attempted dissuasion from local dive masters they went for a dive right beneath the boat. As the dive masters had predicted the bottom was just endless sand (soft sediment) from where the name of ‘muck’ originated, however the dive masters were wrong about one thing, and that is that there was no life down there, quite the contrary, what they found were creatures that looked like extra terrestrials, creatures that even the like had never been seen before, muck diving was born.


A tiny, recently settled juvenile Ornate Ghost Pipefish hangs above a crinoid. Even though this little critter doesn’t know it, the large ‘creature’ in the background is paving the way forward for future research into this unique habitat.

This all happened in the 1980’s, the diving community took a while to catch on, but boy has it caught on, muck diving now is a booming industry which supports thousands of people across Southeast Asia, as Maarten’s research will soon shed more light on. Divers and photographers (and now researchers of course) alike will travel half way across the world just to glimpse these weird and wonderful creatures, and these creatures are not behemoths like the African mammals, no, they are tiny critters which have evolved perfect mimicry and other adaptions to survive in a sandy desert, perfect photography subjects.

So how does a photo story fit into all of this?

Luckily enough for me (well not that lucky, I am referred to as a science hobbit by Mr. De Brauwer, yes, there is an earlier blog about this!) I was able to help Maarten with a large proportion of his fieldwork in North Sulawesi & Bali, Indonesia and on Negros, The Philippines. This gave me a fantastic opportunity to tell a story about this industry and now, the research being conducted. Currently it is quite staggering how many divers travel to muck locations around the world and it is equally staggering how little we know about the ecology, abundances and diversities of these creatures and the threats they face. This is a huge problem, as I have already mentioned thousands of people now rely on the jobs created by the industry and the money the industry brings into countries such as Indonesia and The Philippines. On top of this there is also no baseline data outlining the abundances and diversities of the creatures that have traditionally existed in these habitats, we have no way of gauging how these habitats are responding to the huge increase of direct and indirect anthropogenic pressures.


Arjay Salac is a dive master and one of the figure heads for Atmosphere Resort & Spa’s dive centre. Arjay is from a family of fishermen who live on the adjacent plot of land to the resort, after initially being employed as a landscaper when the resort first opened Arjay took a keen interest in the dive world going on. Enthusiasm and work ethic allowed him to move into a boat crewman position. Through continued excellence in the role he was offered the opportunity of being put through the resorts PADI dive master scholarship. Needless to say Arjay excelled and six years later is now one of the most respected dive guides in the area, eagle eyes are a description which fit Arjay perfectly.

This story is a way for everybody, diver or not, to understand how and why these organisms are so special, the pressures they face and how these tiny organisms have changed the lives of so many people across coastlines in Southeast Asia, and now, what research is being conducted to answer the many, many unanswered questions we have.


A Juvenile frogfish is measured after being caught in one of the S.M.U.R.F‘s. Frogfish, like many of the cryptobenthic organisms, are still unknown to science, this particular individual is most likely a new, undescribed species of frogfish (Antennatus sp.). Note from Maarten: this animal was returned to the ocean alive and well

This blog shows a few small extracts of the story, please visit my site for the full photographic story.


The future generation of instructors, dive masters and dive guides.

Cleaning mutualism on the reef: It’s a Hip-Hop World!


Dr. Simon Gingins

This month’s guestblog is by Dr. Simon Gingins, who currently does research on damselfish at the department of Collective Behaviour in the Max Planck Institute, in Konstanz (Germany). Simon and I met a few years ago at the Lizard Island Research Station, where he was doing research on the behaviour of cleaner wrasses. His blog describes some of his cleaner wrasse research….and hiphop. Besides being a good researcher, Simon is also a great photographer, so make sure to have a look at his site.


An anthias gets cleaned by a bluestreak cleaner wrasse

I know this is old school, but do you remember Eminem’s song Lose yourself? Well, to my big surprise, I recently realized that the lyrics fit very well with the ecology of cleaners. Let me show you by quoting the relevant parts of this song throughout the text. But first, let me start with the beginning. What is cleaning? Cleaning is a behaviour that implies the removal of parasites or dead tissues off another animal. It is widespread, particularly on coral reefs. Many species engage in cleaning, including shrimps and crabs, but it is mostly performed by fishes, as diverse as surgeonfishes, triggerfishes, jacks, butterflyfishes, gobies, and many more. Most fishes only clean occasionally, mainly as juveniles, and get most of their food by other means. However, a handful of species are “professional cleaners” and get all of their food through cleaning. Here, I will focus on the most studied of these species, the bluestreak cleaner wrasse Labroides dimidiatus. This species can have more than 2000 cleaning sessions per day, and client fishes actively visit their territories, called “cleaning stations”. They also give massages by vibrating their pectoral fins on the body of their clients, which was shown to decrease cortisol levels in client fishes. Cortisol is a proxy to measure stress, and thus this additional service is beneficial for clients as is calms them down.

So the cleaner gets a meal and the client gets its nasty parasites removed and a massage. Sound like everybody’s happy, no? Well, the situation actually gets more complicated because the cleaner wrasse prefers to bite client fishes and get a mouthful of yummy mucus, rather than focus on the parasites. Biting client fishes is cheating, but mucus appears to be like crack for cleaners. Or as Eminem puts it:

If you had, one shot, or one opportunity,
To seize everything you ever wanted. In one moment.
Would you capture it? or just let it slip?”

Well, it depends, because of course client fishes don’t visit cleaners to be exploited, and they’re not really happy when they get cheated. So how do clients respond to cheating cleaners? Imagine a client fish with a large territory. Large enough that it has access to many cleaning stations.

“He’s known as the globetrotter”

If it’s not happy with the service of one cleaner, it can just leave and look for another one. Basically, it can play the competition.

 “They moved on to the next schmoe”

This is what my ex-supervisor Redouan Bshary referred to as “big city life”: If you’re not happy with your hairdresser, just go to another one. But some client species don’t have choice options. The size of their territory is more like a village than a big city, and these fishes often have access to only one cleaning station, if any. Cleaners appear to be aware of these differences, and give priority and a better service to big city clients than to villagers. But the villagers still have one trick up their sleeve to make cleaners more cooperative: they punish. When they get cheated, they often chase the cleaner and try to bite it:

“No more games, I’m a change what you call rage”

And it was shown that the next time they meet, the cleaner will be more cooperative with the individual that punished it.


Bluestreak  cleaner wrasses cleaning a grouper

Finally, there is one category of clients with whom cleaners behave very, very nicely: predators. A predator striking at a cleaner during a cleaning interaction has never been witnessed so far. Nevertheless, it’s pretty obvious why cheating a predator might not turn out to be a good idea. To quote Eminem again, in interactions with predators:

“Success is my only m*********ing option, failure’s not!”

In summary, when a cleaner is interacting with a client, eating its preferred food has negative consequences. The client might just leave, but it might also try to punish it, or even potentially eat it. Cleaners thus came up with very strategic behaviours in order to determine who they can cheat, and when it’s best to cheat.

“I’ve got to formulate a plot or I end up in jail or shot”

As already mentioned, they vary the quality of the service they provide according to the category of clients. But it doesn’t stop there, they also adjust their behaviour depending on whether they are being observed by potential clients or not. If a client waiting to be inspected witnesses the cleaner cheating other clients, it might decide to leave and search for a more cooperative partner.

“His hoes don’t want him no more, he’s cold product”

As a result, cleaners behave more cooperatively in the presence of an audience. This ability is quite surprising for such a small fish, since thus far the only evidence that the presence of an audience increased cooperation came from humans. While humans benefit from the computing power of a large brain to take decisions, it appears that the cleaner wrasse L. dimidiatus managed to acquire quite sophisticated behaviours without a large brain. Recent evidence suggests that their exceptional performance might be limited to situations linked to cleaning, and fall short outside of their domain of expertise. It seems that the highly social nature of cleaners and the conflicts associated with it drove cleaners to acquire the skills to deal with these specific situations. But it did not select for increased brain size or some kind of general intelligence. So the next time you go on the reef, I invite you to take some time to observe cleaners and to imagine what it’s like to deal with all these clients coming and going.

“This is my life and these times are so hard”

I’d like to conclude by pointing out that for a guy who claims to have read only one book in his entire life, Eminem proved to have great insights when it comes to cooperative behaviour in fishes. And from what he confesses in another song (Without me), he considers himself an important contributor to fish conservation too:

“No matter how many fish in the sea it’d be so empty without me”

Dr. Simon Gingins


Simon during fieldwork

Postdoctoral Fellow

Department of Collective Behaviour

Max Planck Institute

Twitter: @SimonGingins


Climate vagrants: Guestblog by Joey DiBattista

I have been writing blog posts about my research for over a year now, talking about how interesting my research is. But there is a lot of interesting marine research happening besides mine. So I will now try to get friends and colleagues to write guestblogs about their research, giving you the chance to have an even better insight in what happens in the world of marine biology.

The person to kick off this new section of the blog is Dr. Joseph DiBattista, a geneticist at Curtin University. If you have been following the Critters Research Instagram account, you might have noticed I was up in Shark Bay last week. I was there to help Joey with his research on “vagrants” in the waters of Western Australia. His blog explains more about these vagrants and what they have to do with climate change…

The age of climate change is upon us. This reality can no longer be denied given that the scientific evidence is overwhelming. One of the areas hardest hit by this human-influenced phenomena is our oceans, and the result for our precious coral reefs is often bleaching, bleaching, and more bleaching. Just ask those that study our beloved Great Barrier Reef, a UNSECO world heritage site where only 7% of its corals escaped nature’s wrath in early 2016.


Bleached coral at the Great Barrier Reef. Photo: XL Catlin Seaview Survey

At the same time that corals were suffering in Australia, so were mangrove forests that border the Cape York Peninsula in the Gulf of Carpentaria, which experienced a die-off like scientists worldwide have never seen before (i.e. 7,000 hectares of mangroves left dead or dying…). The recent temperature fluctuations are attributed to this year’s particularly strong El Niño–Southern Oscillation (ENSO), and have now caused bleaching at Indian Ocean coral reefs in the Maldives and at Christmas Island for example, and are imminently predicted for tropical sites further north in the Pacific Ocean (e.g. Okinawa).

It may seem like temperate ecosystems are protected from these warming effects, but no more are we feeling the heat than in the coastal waters off of South-Western Australia (WA). Near the end of the summer of 2011 we suffered through what was aptly coined a “marine heat wave”. Sea surface temperatures from Ningaloo reef to the southern tip of the continent at Cape Leeuwin, a distance of more than 1,500 km, crept up to over 5° C above the seasonal average. This affront was both broad and sustained, extending out more than 200 km from shore and lasting more than 10 weeks. The heat wave killed off more than 100 km of economically important kelp forests (often teeming with their own rich and unique fauna), that have to this day not recovered, but instead may slowly be replaced by corals, a process known in the science world as tropicalisation.

Chaetodon lunula

Tropical species like this Racoon Butterflyfish (Chaetodon lunula) are increasingly found in Western Australia’s temperate waters. Source:

This heat wave in 2011 overlays on top of an already warming trend in WA, which itself has been flagged as a global climate change hotspot. Climate change not only affects the kelps and the corals, but appears to be resulting in tropical and subtropical fish species rapidly moving towards the poles. Indeed, in addition to WA, tropicalisation has caused important changes to temperate ecosystems by introducing tropical fishes to sites in western Japan and off the coast of New South Wales, all themselves bathed in warm water currents that act as vehicles for this fresh “flow” of fish larvae.


Joey filtering water in Shark Bay to extract eDNA

Normally the water temperatures cool over winter months and these juvenile tropical “vagrants” die off, never to reproduce themselves (…sniff, sniff, shed a tear…), but not for some species. In rare cases, enough individuals survived and have now taken up permanent residence in their new southerly (or northerly for Japan!) home. I have a keen interest in these survivors along the coast of WA, where I have started to use next generation sequencing technology to track the movement and diet of these vagrants. This technology is capable of simultaneously sequencing millions of copies of DNA from complex samples, at a not so nominal cost of course. This innovative work is only possible because of a close collaboration with the Trace and Environmental DNA (TrEnD) laboratory at Curtin University in Western Australia. Particularly Professor Michael Bunce, who has extensive experience in isolating DNA from a variety of substrates including bulk bone, faecal material, and, more recently, samples sourced from the marine sector such as filtered water and fish stomach contents. This project remains in its infancy, but with the Department of Fisheries WA supplementing samples and the TrEnD Lab supporting my experimental work, I am confident that we will soon know exactly where these vagrants are coming from and what they are doing once they get here.

Dr. Joseph DiBattista

Early Career Postdoctoral Research Fellow

Department of Environment and Agriculture

Curtin University


Note: For those keen recreational fisherman or scuba divers in WA, there is a website dedicated to tropical fish species that seem “out of place” in their new temperate environment (click here for site). I encourage anyone that spots vagrant fish to take photos and register their important find on this regularly updated website.