The spiral staircase at the Art Gallery of Ontario, shot from below with my Nikon D300s and tarted up in Photoshop to look like a rainbow nautilus shell. The stair, by Frank Gehry, is 11 residential floors high.
The curvature and pearly sheen of this image reminded me of a nautilus shell, although the spiral is not the same. The nautilus shell, in fact, presents one of the finest natural examples of a logarithmic spiral.
According to Wikipedia, nautiluses are the sole living cephalopods whose bony body structure is externalized as a shell. The animal can withdraw completely into its shell and close the opening with a leathery hood formed from two specially folded tentacles. The shell is coiled, aragonitic, nacreous and pressure resistant. The nautilus shell is composed of 2 layers: a matte white outer layer, and a striking white iridescent inner layer. The innermost portion of the shell is a pearlescent blue-gray. The osmena pearl, contrarily to its name, is not a pearl, but a jewellery product derived from this part of the shell.
Internally, the shell divides into camerae (chambers), the chambered section being called the phragmocone. The divisions are defined by septa, each of which is pierced in the middle by a duct, the siphuncle. As the nautilus matures it creates new, larger camerae, and moves its growing body into the larger space, sealing the vacated chamber with a new septum. The camerae increase in number from around four at the moment of hatching to thirty or more in adults.
Image: Copyright Jan McCartney 2012 All rights reserved.