What exactly are spiders?

Chris Smith spoke with spider expert Sara Goodacre from the University of Nottingham to get more acquainted with these 8-legged animals...

Sarah - Well, a spider is an eight-legged creature with a head and an abdomen, and it belongs to a family arachnids, which also has the scorpions and a few other strange and wonderful creatures. And they usually make a whole range of different silks.

Chris - Spiders make silk, but scorpions don't. When did they gain this ability?

Sarah - We don't when the ability to make silk actually evolved in the spiders. But we do know they're the only ones that can do it in that family of eight-legged creatures.

Chris - So if we wind the clock back, how far do we have to go back in evolutionary time to find the first spiders?

Sarah - The first spiders arrived quite a long time ago, around 400 million years or thereabouts, and that's well before insects and other things that you might think arose at around the same time, the spiders are much older.

Chris - It's well before the dinosaurs, isn't it? Cause obviously when one thinks about a spider, you almost always think about spiders' webs and them catching insects. So if they actually predate insects, what did they eat?

Sarah - Spiders when they first emerged ate other creepy crawlies, other arthropods. And they mostly trapped those arthropods either in water actually, or on land, so they weren't flying. And they use their silks sometimes to do this, to create sort of trip wires and lines, there are even trapdoor spiders that create a trap door that they hide under. And then they sneak out and quickly grab something walking by. What they didn't do early on was make the big orb webs that insects would fly into.