Diodon liturosus, the blotched porcupine fish, is a cute, medium sized reef inhabitant. Their huge eyes, and the cute face combined with a usually shy behavior makes them a popular sighting during the dive. You often find them resting in holes.
D. liturosus belongs to the order Tetraodontiformes (the four-teethed), together with sun fishes, trigger fishes, file fishes, and box fishes. Diodontidae contains 18 species. The other family of pufferfish is Triodontidae with approximately 200 species.
Pufferfish are said to be the 2nd most poisonous vertebrates in the world, after the golden dart frog. The substance Tetrodotoxin (TTX) is very potent. It is widely used by molluscs, fishes, and amphibians. It’s not 100% understood, but it seems bacteria of different species produce the TTX. I tried to find out which puffer species are the most poisonous. But it looks like it varies with regions or food sources, or maybe even seasons? Takifugu rubripes, the tiger pufferfish is mentioned as one of the most poisonous edible puffer. I wonder if there’s non edible puffers, I mean what else can stop us from eating them, if not the TTX?
Now you would think they leave you alone when you managed to be number 2 in the poison ranking. But they don’t. There has been this video of dolphins playing with puffers in the 2014 BBC documentary ‘Spy in the pod’. People are assuming the released TTX is like a drug to them. Until now this is speculation and not proven. In the end a puffed pufferfish could just be a ball to them. I imagine it hard to consume the poison in the water. You would have to drink a lot a sea water, right? It is not 100% understood, but scientists believe that marine mammals get a huge portion of water from their diet. They must however have an adaption to be able to filter out excessive salt. I have made another observation. A moray eel caught a blotched porcupinefish right in front of me and my dive buddy Hans Jürgen, whom I’d like to thank again for the video. The moray had a hard time to get the spiky ball out of his rock. You could even hear the spikes scratching over the rock. Did the moray get high? I don’t know. Unfortunately we could see how this story ended.
The tiger puffer is one of the puffer species consumed as fugu in Japan. China produces thousands of tons (!) of T. rugripes in aquaculture. Every year. That’s millions of pufferfish. Raised under controlled conditions, it is claimed that they do not contain TTX. So you get the thrill of eating a super poisonous fish, which doesn’t contain the poison. Please make sure you know what you eat, and how to handle it! But that’s not all I have for pufferfish.
A Diodon is mentioned by no one lesser than Charles Darwin himself. The soccer ball-sized fish with the cute face shares a secret with one of the most famous person in history. You can find it in ‘Voyage of the Beagle’, his book about the five year journey on ‘His Majesty’s Ship Beagle’. For better confusion, this was actually the 2nd Voyage of the Beagle, and the only one Darwin joined. There were three in total. The third one was rather uneventful, but the first one was a desaster including the suicide of Captain Stokes, and the abduction of four natives, so called Fuegians, including two children. Yokcushlu was one of those four, a girl, which later joined the 2nd voyage.
It was THE famous trip that brought Charles Darwin to Galapagos. With the finches. Evolution. Survival of the fittest. But let’s sort that out quickly. Darwin and Alfred Russel Wallace said in 1858 that evolution is caused by natural selection. Darwin published in 1844 already an essay called ‘Extract from an unpublished work on species’. You often find the number 500. Darwin collected almost 500 birds during the (2nd) Voyage of the Beagle. Some of them were the Darwin finches from Galapagos. He noticed different beak forms, and gave those birds to the ornithologist John Gould.
Darwin’s grandfather, Erasmus Darwin, published ‘Zoonomia’ from 1794 to 1796. There he anticipated the development of new species ‘directed by irritations, sensations, volitations, and associations.’ It’s remarkable how carefully he formulated his theses, starting the sentence with ‘Would it be too bold to imagine…’.
Another important name in the understanding of evolution is Jean-Baptiste Pierre Antoine de Monet, chevalier de Lamarck (yes that is one name). He published his theories from 1800 onwards. Lamarckian evolution includes the belief that creatures can already change during their lifetime, what is now called epigenetic modifications. Genes can change their activity.
I wondered if Darwin’s father was also into evolution. He was a medical doctor who found evidence for microsaccades, the tiny involuntary eye movements, that seem to keep our brains screensaver off. No evolution in his work. But there are many others involved in the theory of evolution, for example Saint-Hilaire, Oken, and Grant.
Back to the voyage.
On Fernando de Noronha, an Island east of Brazil, February 1832 if I’m not mistaken, he was handling a Diodon antennatus. This fish is not a Diodon anymore, it is currently called Chilomycterus antennatus. He described the puffing mechanism, and the sharp teeth. And he mentioned something I couldn’t find an explanation for. This kept me busy for a while.
‘A carmine red fibrous matter, secreted from the belly of the Diodon. So intense in color, that it stained ivory and paper permanently.’ he wrote.
And there my quest begun. Fishes using ink for defense? No results nowhere, only that cuttlefish produce ink. But Charles Darwin would have noticed if his fish was just bleeding, wouldn’t he. I asked in Ichtology groups on Facebook, I asked in an aquarium-keeper forum for puffers. No explanation. Puffers do release poison when handled, ask the dolphins. But TTX is colorless. I couldn’t find out what color the defense liquid has though, for sure it’s not pure TTX. Could be the answer, but he did not describe typical symptoms of TTX poisoning. Which he should have experienced when his hands were red.
Was it parasites, algae, or even a mistake, maybe a mix up in Darwin’s notes? What did you see Darwin, what happened? Just to put this into context. Darwin was only 22 years old when he went on that journey. OK he was almost 23. It was initially planned for 2 years. He was heavily sea sick (or was he poisoned by the puffer?), and he has made an overwhelming amount of experiences on that trip. He collected thousands of animals. Meta AI gave me some numbers I wasn’t able to find anywhere else. When I asked how many animals he and his team collected, the result was 5436. When I ask for each different order of animals, the numbers add up to more than 5436. For example it says 200 mammals, 444 reptiles, 1529 fish, 1529 plants, 216 arachnids, 78 amphibians, 3,907 insects. 6874 animals in total, plus the 500 birds. I wonder if that’s somewhat true, no guarantee at all here! But it’s a lot, and I myself wouldn’t be able to keep track of all my observations. The mystery stays between Darwin and his Brazilian pufferfish.
English 
Deutsch