Not strictly traditional Haiku
Isn't that lovely? I wonder what it is? As you called it a grass sea, how about using 'anchors' instead of 'catches' - to keep it nautical?
I was thinking that 'grass sea' described the location and lended a smallness to it. I chose 'catches' to hint at fishing net, which is sort of what the spider is doing there. ('Anchors' would work too, but it sounds too much like 'angers' - LOL!)
Nice image & words.Aloha from Waikiki Comfort Spiral