The Enormous Mass of a Dead Sun(fish)

Today’s news contained an astonishing (albeit rather sad) piece of news concerning the Tetraodontiforme order of fish.

In December 2021, a dead giant sunfish (Mola alexandrini) was discovered in the ocean off Faial Island (which is part of the Azores–a Portuguese archipelago in the Atlantic). “Giant sunfish” is the common name for this sort of sunfish–but this time it was more than a name. The dead fish was enormous. When scientists dragged it to shore and weighed it with a special forklift, they discovered it had a mass of 2,744 kilograms (6,050 pounds), which means it is the largest teleost (bony fish) ever recorded (although, obviously, some long extinct fossil species were much larger). The fish was 3.59 meters long and had a huge blunt contusion on its head which was clearly caused by a boat collision (as evinced by the fact that there were fragments of boat paint on the affected area).

Scientists are still studying the specimen (indeed, they only just released word of it to the world) and a full necropsy has not yet been performed to determine the cause of death. Perhaps a boat hit the fish after it was dead. Still, it doesn’t take Hercule Poirot to start connecting the dots (which is to say, I have a feeling the fish was killed by a fast moving boat–a fate which is all to common among the larger and faster rorquals). The death of this giant is a tragedy in its own right. Yet it is stunning to me that we only just found the largest specimen of bony fish on record. The ocean still abounds with life and miraculous secrets. It could recover… if only humankind would allow such a thing!

A few years ago, I wrote about Mola alexandrini’s close relative Mola mola, the ocean sunfish (which I misidentified as the world’s largest bony fish). Obviously I was mistaken! However that post summarizes what we know about the way both these pelagic giants live. It also addresses baby sunfish–for both species go through a larval stage when the 2 millimeter long babies (!) drift around as part of the plankton. Weighing less than a gram, the li’l baby sunfish are spherical and covered with translucent triangular spikes to deter predators. The sunfish got its name because it likes to sunbathe near the ocean’s surface (another piece of evidence in determining how the Azores giant specimen met its end), however, I think the little ones actually look like the suns drawn in Renaissance woodcuts.

I will keep you updated when (or if) we learn more, but in the meantime I hope you are struck with wonder by these magnificent denizens of the ocean (and, if you are a boater or mariner, I hope you drive your vessel with care and consideration).