Sunday, September 9, 2012

Point Insertion

They're waiting for you Gordon...

I guess this means I'm devoted to updating everyday before the release, doesn't it? Well that's perfectly fine because I just realized that in all the time I've maintained this blog I haven't told you about our good friends from the sea: the Nautiluses.

The cephalopod family Nautilidae has survived in one form or another for the past million years. Today, this family of mollusks are the only living members of the superfamily Nautilaceae, belonging to the subclass Nautiloidea of the class Cephalopoda which of course includes octopuses, squids and cuttlefish. Because the Nautiluses have been around for so long they're considered living fossils.

Compared to their glory days, there's not many of them around anymore. They're found only in the Indo-Pacific on the slopes of coral reefs, usually at a depth of a couple hundred meters. It used to be a very different story back in the early Paleozoic Era when the oceans were completely dominated by hard-shelled cephalopods of all sizes and shapes. In those ancient times the Nautiloids were the undisputed masters of the seas, making up the bulk of the whole predatory population of the entire planet.

Compared to their shell-less relatives, the Nautiluses are fairly simple animals, especially when it comes to eyesight. Unlike the cuttlefishes who try to rival the mantis shrimps for sheer visual power, the Nautiluses make do with a highly developed, but lensless structure that acts like a simple pinhole camera. They usually rely on olfaction when foraging, sniffing out prey like a tentacled bloodhound.

They don't swim like other mollusks either. Their shells are chambered like a submarine ballast. When water is in the chamber salt is extracted and diffuses into the Nautilus's blood, making them more buoyant. If they want to sink they remove liquid from their shell chambers.

Speaking of which, Nautilus shells form pretty close approximations of logarithmic spirals. Vortexes like these can be found throughout nature; such as in the growth of broccoli, sunflowers, hurricane clouds and even the spiral arms of galaxies.

The turnings of logarithmic spirals increase in distance according to a geometric progression, meaning the further out they spiral, the wider it will get and the greater the distance will be between each successive "layer" of the spiral. This is different from Archimedean spirals where the distance remains constant.

Nautilus shells are sometimes used as examples of Golden Spirals in nature, even when they're obviously not. The confusion probably stems from the fact that golden spirals are logarithmic spirals just like Nautilus shells. But the growth factor of a golden spiral is the golden ratio, about 1.61803... which would be way too wide for any real Nautilus. I have no idea what the geometric progression is for most real Nautiluses but if I ever meet one I'll be sure to ask.

In any case, it doesn't matter if they're proportional to the Greek Parthenon or not. Because at the end of the day they're still primordial, hard-shelled, submarines with tentacles. If that's not cash, I don't know what is.


Oh, and before I forget...

...It's Bunday.

1 comment:

mom said...

ask nana to show you my post from last monday from FB. you will love it

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