I once watched a spider in a web have to rapidly run around it's web and scoop up it's little baby spiders to escape a flame that was coming close to it. The reaction did not appear to be some kind of mechanical automated reaction - it very clearly had awareness of the danger, and an awareness of it's offspring, and made a coordinated effort to rescue them and move them away to safety.
To me - as someone who is not a biologist or a professional in this field - this appears to be consciousness. I couldn't imagine anyone trying to argue against that.
Optimize a creature for "survival" over billions of years and you get behavior like this. It doesn't require consciousness however. And it's quite hard to ask a spider whether it is conscious or not.
As the top comment in this thread pointed out, we don’t have a definition of consciousness that allows you to tell whether a spider has it or not. As far as I know, no observable behavior requires „consciousness“ for most layman definitions of the term.
To me - as someone who is not a biologist or a professional in this field - this appears to be consciousness. I couldn't imagine anyone trying to argue against that.