A newly published study from University of Galway sheds light on why some spiders are far more venomous than others.
It looked at more than 70 different species to determine what factors decide how deadly they are.
We all know that big spiders can be harmless and small spiders can pose a serious risk - but have we ever asked why?
The team at University of Galway was determined to find out, by examining if factors like body size, prey type, hunting methods and web types make a difference.
Their conclusion is that diet is the major driver in determining the potency of spider venom.
Spiders who exclusively munch on flies and other insects have evolved with venom effective for that purpose - but are relatively harmless to human physiology.
But species that mostly eat insects but sometimes prey on small mammals, like the Black widow, have venom that evolved to significantly effect humans.
Luckily for us, the spiders we find here colonising corners, resting on our pillows or relaxing in the bathtub are the insect loving type.
Researchers had also predicted that web-hunting spiders would have less potent venom, because they evolved to rely more on their webs to catch prey.
But, to their surprise, they found no link whatsoever.
