Spider Type 12====Red-back spider

This spider is called the red-back spider which is one of the ten most dangerous spiders in the world. it's a extremely venomous smart spider in Australia. The length of this spider is different as the body of females is ten millimeter long while male is only 3 millimeter long. These red-back spiders usually live in a warm area. The red-back spider is extremely dangerous and can be possibly and seriously harm humans. 

reference:

http://en.wikipedia.org/wiki/Redback_spider
http://www.australiangeographic.com.au/topics/wildlife/2012/08/australian-spiders-the-10-most-dangerous/