Cheilinus undulatus – A Napoleon you cannot poison!

To make it very clear, this post is about a fish, and not about the French leader. Also I neither support nor deny the theory of Napoleon being poisoned.

Our fish is a popular sighting for scuba divers, and its common name makes it an easy to memorise fish. A Napoleon wrasse, or Napoleon fish, is a huge thing, that reminds me of a swimming furniture underwater. They usually swim more or less motionless, and you could think emotionless, along the reefs. They are often accompanied by travellies or groupers, and sometimes hang around foraging stingrays as well.

So why is this fish associated with Napoleon? It must have to do with the hump on the forehead of adult C. undulatus. So is the underwater signal for this animal often a fist hold to the forehead. On you can find descriptions of eyewitnesses of that man. His forehead is described as wide and broad, but looking at paintings I cannot imagine that his head was as remarkable as our fish’s. Napoleon Bonaparte’s hat, a bicorne, has a kind of hump, what could be the better association to our fish. Another signal for Napoleon fish is his hand held to the chest, like Napoleon used to put one hand in his shirt to look more noble. C. undulatus can grow bigger than our historic French leader, reaching more than 2m. Marshall reported a 2.29m fish in 1964. Napoleon by the way was not as short as often referred to, he was 5.2 French inch, what is more than the Imperial inch, so he was around 1.7m.

That impressive size makes the Humphead wrasse, or Napoleon, the largest member of the family Labridae. Wrasses are with over 600 species a common marine fish in coral reefs around the globe. I have no explanation why these often very pretty fishes are called after the kind of celtic word wrath, what seems to mean old, and maybe ugly looking old woman. No idea. Rüppell, a German with no obvious connection to France, described C. undulatus in 1835, just 14 years after Napoleon’s death. It is one of seven Cheilinus species. They start their life as tiny larvae, less than a millimeter long. Look out for black and white juveniles in the reef on your next dive!

Like 30.000 other species of bony fish, our fish belongs to the class of Actinopterygii, the ray finned fish. The other class of bony fish is called Sarcopterygii, the lobe finned fishes. Unbelievable, only eight out of 27.000 known species of Sarcopterygii are not extinct.

My story related to the Napoleon wrasse is about poison. There are rumours that Napoleon died of either arsenic or cyanide poisoning, and obviously it is a bit difficult to come to a final conclusion here. Arsenic was widely used in various applications during his time, so it is no wonder to find it in his tissues.

What got my attention is that our big fish is able to eat poisonous animals. In “Food habits of the giant humphead wrasse, Cheilinus undulatus (Labridae)” from Randall, Head and Sanders, 1978, it is mentioned that remains of crown of thorns starfish (CoTS), sea hare and boxfish were found in speargunned Napoleon wrasses.

I actually struggle to find any other source confirming that information. Kroon published 2021 a paper, with the good news that more than expected marine animals prey on CoTS. And they claim, no big wonder, that overfishing has a negative impact on the ecology of a reef. In that case intense fishing of especially emperors and snappers might be a reason for overpopulation of CoTS. Their source for Napoleon wrasses as predators of CoTS is the “Survey of marine scientists and other experts for anecdotal observations of crown of thorns predation” published in 1991 by the Great Barrier Reef Marine Park Authority. Out of 100 reported preyed-on CoTS almost half were eaten by the giant triton, a snail. Second most predator is the Napoleon wrasse, also called Maori wrasse. Fun fact, only source for this is a Mr. L. Squires, who never witnessed a wrasse eating the starfish, but seems to like the fish in a culinary way. He found remains of CoTS in the fish. Not sure if he’s related to the Squires fish restaurants in England. In Australia C. undulatus is protected since 1998.

In fact, there’s only two people in literature I found as witnesses for CoTS in C. undulatus stomachs. Our first source, Randall himself wasn’t one, he names a Walter L. Starck, who reported his observation from one fish caught in 1971! My search is for sure not complete, but still I find it remarkable. Why is there such thin evidence?

I also couldn’t find footage on social media showing a Napoleon eating a crown of thorns. Divers, maybe this is your chance to shine! Share your observations to support science!