Fish shows the value of keeping a clear head

There are many species of cave fish that, after millennia in utter darkness, have either lost their eyelids or lost their eyes entirely. You might think that losing your eyelids is a way station on a one-way trip to blindness. But the barreleye fish (for its tubular, or barrel-shaped, eyes) lost its eyelids even as its eyes were bulking up and becoming more powerful. Barreleyes live in the deep sea where there is still just enough light filtering down from the surface to silhouette a snack, provided you are looking straight up and have the necessary light-gathering equipment.

So, let’s say you are Mother Nature and you are presented with this puzzle: giant tubular light-collecting eyes and no eyelids. Hmmm… what to do? I know! Why not evolve a transparent head?

Look at this picture.


The things that look like eyes are actually nose-like things called nares. The head itself is clear, and the eyes are those giant green things lodged deep in the head jelly. In fact, the green things are the lenses on top of cylindrical eyes, and they point straight up, perpendicular to the body axis, like a twin telescopes in a sheltering observatory dome.

Now, look at the picture again and read the last paragraph again. It may help to mutter to yourself those are not eyes… those ARE eyes. It takes a while to sink in.

I don’t blame you if you don’t want to take my word for it. Read more about it here: MBARI News Release – Researchers solve mystery of deep-sea fish with tubular eyes and transparent head. That Mother Nature… where does she get her material?

Thanks to Greg Wilson for the tweet on this one.

The History of Fishes

See this fish? He’s bad news.

This is not just any fish. This fish nearly punched the lights out of the Enlightenment.

Oh, he seems likable enough for a red gurnard. But at parties, after he gets into the brandy, he parades around and insists on being called Aspitrigla cuculus of the Scorpaeniformes (I understand they have a lovely place by the sea). And in his day he was capable of some violence: this cuculus nearly killed calculus.

The picture is from Francis Willughby’s De Historia Piscium, also known as the History of Fishes. It is a lovely piece of work filled with detailed illustrations, but it is especially distinguished by a curious footnote. Published at great expense in 1686 by the Royal Society, it was a commercial flop. So much so that they Royal Society lacked the funds to proceed with its next offering: Isaac Newton’s Principia Mathematica. It is only because Edmund Halley “saw something in this Newton kid” and underwrote the first edition Newton’s magnum opus that any of us exist, since as you know, if the Principia had not been published, none of us would be here today.

There’s a paper on the History of Fishes by Sachiko Kusukawa. It’s behind a registration wall, but the abstract is fun reading. Here’s an excerpt:

The Historia Piscium was a work begun by Francis Willughby (1635-1672, F.R.S. 1663), completed by John Ray (1627-1705, F.R.S. 1667) and brought into print with the financial support of The Royal Society. The text and illustrations of the Historia Piscium reflect the 17th-century origins of the enterprise: Ray’s quest to recover the knowledge and language lost in the Fall, and The Royal Society’s support for establishing a reformed natural history of fish through publication. Ray’s biblical belief in the corruption of human language and knowledge led him to reform natural history through ‘characteristic marks’. He sought to define, classify and depict fishes through their external features, which when matched up, would yield the same nature, and thus allow humans to identify and give a name to a fish.

This leads to a pet topic of mine. Christianity figures prominently in many scientific histories. Often enough, misplaced theology led to good science, and in aggregate this science ultimately led to the modern Western scientific mindset (which in turn put pressure on Christianity, but that’s another story). In the same way that magical alchemical reasoning prepared the way for modern chemistry, was there something special about the Christian mindset in the High Middle Ages that put European science on its spectacular ascent?