Round and round she goes...

Spirals are characterised by having a starting point from which they radiate, twisting round and round indefinitely with the perfect distance from the centre and to the edge of the spiral.

Some of the spirals found in nature are flat, or two-dimensional, although there are also many examples of three-dimensional spirals that twist upwards in the shape of a cylinder or cone. Such a three-dimensional spiral is called a helix, which is the Latin word for snail. If you look around at the beach, you are sure to find examples of such snails. Some of the very nicest snail shells are known as conches. If you study the patterns in beautiful shells, you will no doubt find spirals there too.

Let's see where we can find spiral shapes in nature:

• If we start with the inconceivably large, we see that the stars form spiral nebulae.
• The nautilus octopus lives in a house that grows as the octopus grows. What is more, the house grows in an absolutely perfect spiral shape. The distance between the spiral loops even increases further out in the spiral, giving the octopus room to grow.
• We find spirals in many seashells and snail shells.
• The seeds of sunflowers and daisies produce spirals. The same is true of pine cones and pineapples.
• Most spiders spin their webs in a spiral shape.
• In the human ear, there is an organ known as the cochlea. This is where sound waves are converted to electrical signals that are transmitted to the hearing centre in the brain. The cochlea has a spiral shape.
• The DNA molecule, containing the secrets of our genetic make-up, has the shape of a spiralled helix. The same applies to the horns of mountain goats.

Why has nature chosen such spiral shapes? Is there a mathematical formula? If we look at the spiral shape of the sunflower, for example, it turns out that this particular spiral shape allows the cells to grow as close together as possible. Even the tiniest shift in the spiral formed by the seeds would cause a lot more air between the cells, resulting in far less efficient utilisation of the space. Nature chooses the most 'rational' route, which also turns out to be beautiful!

Translation: Linda Sivesind

*Published in 'Nysgjerrigper' 3, 2000*