Smart Spiders

Spiders produce silk that reflects ultraviolet light and warns birds.

Glass facades on buildings are responsible for millions of bird deaths each year. The trouble is that glass windows reflect the landscape and birds collide with them. Birds rarely collide with other hard-to-see things, like spider webs. Maybe we could learn something from spider webs to help us design better windows?

1. Draw a spider web with a UV marker. It is invisible to the human eye.
2. Now use a UV lamp, and the spider web becomes visible.
3. Give an explanation, based on pupil ability (see explanation below).
4. If available, show pupils samples of bird-safe glass. It is covered with a pattern similar to that of a spider web, made of a UV reflective coating. The 'web' is visible to birds, but not to the human eye.

The construction of spider webs is inspiring in many ways. One of the successful strategies used by spiders is incorporating UV light in their silk. 

Simple explanation

Some animals see better than humans, some worse, and not everything is visible to humans. For example, cats and dogs can only see two colors, some snakes are able to see infrared light, and birds (unlike humans) can see ultraviolet light. Spiders produce silk thread that reflects ultraviolet light. In this way, some insects are attracted to the web and become trapped while larger animals such as birds are deterred.

More detailed explanation

Birds see differently than people. The human eye is unable to register light at UV wavelengths but birds, as a result of evolutionary advantage, can perceive light in the UV part of the wavelength spectrum because they have four types of photoreceptive cones in their retina. Because of this, birds see spider webs and do not bump into them.

Ultraviolet light attracts many species, including insects. Some flowers take advantage of this by drawing patterns on their petals to attract pollinating insects. These patterns are invisible to the human eye.

By mimicking the strategy used by spiders to warn spiders with UV light, engineers and scientists have designed a special coating for glass that can make windows bird-safe. This protective coating is invisible to the human eye, but birds can see it. This special glass helps to reduce bird collisions with glass buildings.

Some STEAM opportunities include:

• Observing how different animals can see different ranges of colours and light.
• Observing and raising questions about how different animals adapt.
• Analyse advantage and disadvantage of different adaptations/behaviours.
• Explore light phenomena such as how light can be split into different colours.

Check out this interesting study on bird safe glass (find out more).

Here you can find more about this biomimicry story (find out more).

This manufacturer is using biomimicry in their glass production (find out more).