"Just the place for a Snark!" the Bellman cried,
As he landed his crew with care;
Supporting each man on the top of the tide
By a finger entwined in his hair.
"Just the place for a Snark! I have said it twice:
That alone should encourage the crew.
Just the place for a Snark! I have said it thrice:
What I tell you three times is true."
Lewis Carroll (1874), The Hunting of the Snark.
This much is true: cymothoids are stranger than any Bandersnatch or Boojum that I’ve ever seen, especially those found in freshwater. Brazil harbours the largest diversity of freshwater cymothoids in the world, with 24 species currently recognised. These species are quite distinct from their marine relatives, both ecologically and morphologically. For example, and surely equal on the bizarre scale as the famous ‘tongue-biter’ (Cymothoa exigua), species of the genera Riggia and Artystone burrow themselves within body cavities of fish wriggling and poking their legs out through the hole to maintain contact with the outside world! From a phylogeographic perspective, how, when and where did these frabjous beasts adapt to life in freshwater? Did this ecological shift occur concurrently with African freshwater species, or has colonisation of this habitat occurred multiple times? Or, controversially, did they even have a marine origin? In Brazil alone there certainly seems to be a north-south divide in species composition which might indicate different ancestral origins; the distribution of Riggia and Isonebula confined to southern river basins. I needed to find out what was going on, we had to include these species in our project, and that meant only one thing: hunting the Snark in Brazil!
To guarantee collection of a diversity of specimens, I first headed to the National Institute of Amazonian Research (INPA) in Manaus – the base of the late Dr. Vernon Thatcher, who described most of the freshwater species in South America during his prolific career. When at INPA working on fish parasites, it makes sense for one to have a quick peek at the fish collection. It is MASSIVE: full of potential discoveries just lying around in buckets about the place, the scale of which will take decades to sort through and catalogue. The guys also keep a live ‘pet’ electric fish out the back in a tarpaulin tank. INPA is where I stumbled into my first (re)discovery, thanks to the awesome Dr. Rafaela Ota and her gold-standard silver dollar (genus Metynnis) expertise. This appears to be a whole new genus of cymothoid, which was identified by Dr. Thatcher himself, but never formally described. The host of his specimen was incorrectly identified as Metynnis lippincottianus, making this the sole cymothoid species known to parasitise M. maculatus. We can safely make this claim because we also discovered that the host of Isonebula maculatus, is not M. maculatus but M. lippincottianus. What a mess: unfortunately, typical of cymothoid taxonomy!
“They sought it with thimbles, they sought it with care;
They pursued it with forks and hope;
They threatened its life with a railway-share;
They charmed it with smiles and soap.”
In addition to the unusual cymothoids found there, another plus about Brazil, we thought, was that rivers represented a smaller haystack in which to collect a diversity of fresh material than the vast ocean. August would also be particularly good for fishing when waters are low. With a decent haul of 14 tissue samples from 11 species, I left Manaus for Belem where the Federal University of Para (UFPA) was to be my base from which to launch cymothoid hunting operations along the Rio Tocantins. This basin looked like a decent target: it had not been sampled except in the upper reaches of the Araguaia contributory, had ‘good’ access, we had ‘good’ contacts with fishermen, and they had reported ‘good’ sightings of cymothoids. I quickly discovered that planning anything in detail beyond this outline was about all I could hope for without inflicting severe trauma upon myself through repeated and fierce cranial contact with a brick wall. There was only one thing for it; set off and work out the detail on the way – at least I knew I was heading for Maraba. My generous host in Belem, Dr. Jonathan Ready, could not join the expedition, so we assembled a crack team of postgraduate students each working on different fish groups (Stingray, Catfish and Electric) to accompany me on the trip and fulfill some of their own sampling objectives. The car was loaded with nets, tubes, dissection kits, buckets, biscuits, water, bags, maps, a vat of formalin and, somewhere, a risk assessment. Oh, and I was driving…
The trip yielded far too many stories to recount in a short blog post but there are some particular highlights, and not-so-highlights that suffice to illustrate my experience of fieldwork in the tropics. One evening, en route to the boat we had booked in Sao Joao do Araguaia, we came across a line of stopped cars just outside a small village. We should have realised due to the remoteness, and the late hour, that this was not ordinary congestion. The plumes of black, acrid smelling smoke erupting from a fire just a couple of cars ahead of us should also have given us a clue. The road was barricaded, a riotous protest had consumed the village, and its residents’ were hurling rocks at our cars and abuse at the officialdom of the region. This action, it transpired, was quite justified; they had been without running water for seven days and nobody had come to look, let alone fix the problem! We decided to take the back road. This was a road that you imagine every highway to be like in the Amazon, and are secretly disappointed they aren’t: precarious log bridges over narrow ravines, dust so thick you can’t see the road, no passing places whatsoever, and oncoming trucks in clear contravention of the handwritten signs stating ‘not suitable for heavy vehicles.’ What an adventure! But the adventure of that day didn’t stop there. Brazilian roads are notoriously rubbish, and most people at night drive with their high beams on to illuminate the automobile pitfall traps that litter the asphalt (incidentally, asphalt means they are ‘good’ roads). The result is that, blinded, nobody can see the road let alone these pockets of oblivion. It was inevitable that at some point I would crash into one, tearing the off-side tyre from the now buckled rim and cracking the suspension. In the pitch black, by the side of the road, we unpacked the vat of formalin (now full of fish) and the rest of our gear to get to the spare, swapped out the old tyre, and then gingerly limped back into Maraba for a beer.
“They hunted till darkness came on, but they found
Not a button, or feather, or mark”
The first few days of fishing were awesome! I have never seen such beautiful, such quantity, and such diversity of fishes in one place. We quickly collected and processed stingrays and catfish for Stingray and Catfish, and amassed hundreds of other specimens for Jonathan’s biodiversity work. Unfortunately, there were no cymothoids. The fishermen at Sao Joao told us they usually saw baratas do peixes (fish cockroaches) in piranha, but at this time of year we would be better trying remoter streams. Following hearsay and whispers of sightings from the fish stall holders in Maraba we ended up in another far-flung village and met with a man who had a 100 metre net, a boat with shaded cover (a blessing in 40⁰C heat) and knowledge of an exclusive spot way up river where he always encountered piranha with baratinhas (little cockroaches). We fixed a price, headed off to get supplies, and returned full of excitement to find the guy had snuck off to the pub and was now steaming drunk. Thankfully, the heat makes long-lasting inebriation quite a challenge and an hour into our journey I was glad I had gambled on his sobering up. Again, we enjoyed a lovely cruise and caught many fish, however, none of these fish carried cymothoid passengers.
"We have lost half the day. Any further delay,
And we sha'n't catch a Snark before night!"
And so things went for the rest of our time in Maraba. We knew cymothoids were there but it felt like we were always one step behind, one clue short of solving a mystery, and it was beginning to get frustrating. Our mimsy was further enhanced when we discovered that the fishermen at our next stop in Cameta wouldn’t take us fishing because of some unclarified licensing issue. We needed a new plan, and fast. Catfish, Stingray and Electric jumped into action and we were back in the battered mobile driving to the research institute in Tucurui. Here we met Luciano who runs the institute’s Tambaqui (Colossoma macropomum) aquaculture research station. He had often seen cymothoids attached to the caged fish – I guessed the most widespread freshwater species, Braga patagonica, that is usually a gill parasite of serrasalmids but has been recorded as externally attached on Tambaqui. I use the word ‘guessed’ because after getting out to the pens on the vast dammed section of the Tocantins (about an hour boat trip) and individually checking over 1,000 fish, we still didn’t find any! This additional disappointment led us into our next big adventure.
“Without rest or pause—while those frumious jaws
Went savagely snapping around”
Our boat driver’s son was a fisherman that lived on a nearby island (another hour) with his wife’s family, and he suggested that we pop over to ask where the best fishing places might be. The thought of this gringo scouring the lake for cymothoids caused some amusement among the family but they were also deeply interested in my research and seemed eager to help. Importantly, they said they found piranha with parasites every day. Accepting a kind invitation to stay on the island and fish with the family we headed back to Tucurui to gather our hammocks, gear and food. The return voyage back to the island was made more interesting by a huge thunderstorm that whipped up waves, and brought a deluge of big rain that soaked us all. This was the only time in Brazil that I felt cold. In fact, we were all freezing by the time we arrived in the dark three hours later (the chop meant we had to take it easy). A quick wash in the river (with the stingrays, caiman and piranha) and a change of clothes thawed us out a little, and we were grateful when we found that our amazing hosts had cooked us a huge meal. This was one of the loveliest families I have ever met, anywhere. They were so connected to the environment, incredibly generous, humble and a great laugh. Over dinner they told stories of life before the flooding, and the effects on the animals and plants on which their lives depended, about fish and politics, and more fish. It turned out they also hated cymothoids - the matriarchs of the group claiming that unless they were killed immediately after a catch was brought in, the little critters would infest and kill their chickens! Unlikely, but a good story and a good sign that the island was a good idea. And it was! That night we finally found our first cymothoids – Braga patagonica in the gill cavity of Pygocentrus nattereri whose jaws went savagely snapping around. That night I slept peacefully in my hammock on an island I didn’t quite know the location of, in a lake in the Amazon, as the storm still flashed on the distant horizon.