African Wildlife & Environment Issue 77 FINAL ISSUE

LIGHT THE WAY Web decorations used by in the orb web spider reflect light in the UV range. Birds can see this and avoid the web. One of the greatest dangers facing our birds is glass, because the glass is reflective and transparent, and the bird does not see it as a barrier and tries to fly through it.This can lead to hundreds of thousands of bird deaths every year! Research has been done on why there is a low chance of birds flying into orb webs and the discovery was made about the UV light web decorations.A glass company has taken on this concept and created a glass covering with a patterned UV coating. Birds can now clearly see the UV patterns in the glass and avoid it.When we however look through

the glass it appears completely normal as we can’t see light in the UV range.

Spiders are very crafty and their webs are beautiful

GREEN GLUE Some of the spider web glue is super sticky and is a wonderful biological glue. Researches are making environmentally friendly glues based on the spider silk recipe that is non-toxic to the environment and safe to the user. Spider silk is such a fascinating material.The fact that it is safely made by the spider and stored and ready to be used when needed has created so much interest in how we can learn to manufacture our products. Time to watch a clip (just click on the play button on the left)

JUST HOW DOES AN ORB SPIDER BUILD ITS WEB?

Grab a pencil and trace how the orb web spider builds its web

The spider creates the bridge line. One of the ways that the spider builds a bridge line is to dangle some sticky silk in the air waiting for it to be carried to an attachment point. Once this has happened the spider crosses back and forth over the line to make it stronger. The frame of the web is then constructed Once the frame is constructed, another line is drawn across the bridge and when the spider is in the middle of the thread, it draws the thread downwards to the centre of the web. It then continues downward with a single thread.This creates aY silken thread. The spider then adds further radi threads to strengthen the web. Then the spiral web is constructed also known as the catch web.The spider then takes up position in the middle of the web

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(Martin R Filmer – SA Spiders)

SPIDERS TUNE THEIR WEBS LIKE A GUITAR Spiders can control the tension and stiffness of their webs to help increase their awareness of what is going on in the web. Much the same way as notes travel along a guitar string, spider silk transmits vibrations, sending information back to the spider. Spiders then use this information to understand where their prey has been caught in the web.The vibrations also let the spider know if it is coming from prey or another spider. A lot of males will make a specific musical pattern communicating with the female. Click on the play button to watch spiders tune their webs

51 | African Wildlife & Environment | Issue 77 (2020)