What does the "qui" mean in "crabes pressés qui disparaissent"?

Question

I'm reading a novel titled "Attention aux pickpockets". Here is a paragraph describing a young man drawing on a bulletin board in a train station:

Oubliant ses problèmes, son renvoi et les yeux tristes de son père, le jeune garçon s'attaqua au panneau. C'est fou comme le métro ressemble à la mer… Le béton des quais, c'est la plage, les trains passent les uns après les autres, comme des vagues, des voyageurs montent ou descendent, petits crabes pressés qui disparaissent. Il y fait chaud et un soleil artificiel ne laisse jamais place à la nuit. […]

I fancy "crabes pressés qui disparaissent" means "crabs hurrying up and leaving"… but how to understand the "qui" here?

I know "qui" normally means "who" in English, it's used to glue up the main sentence and its clause. But grammar-wise, what does this "qui" serve here?

Answer 1

The meaning of qui is who. I'd translate that frament as hurrying crabs who are leaving or squeezed crabs who are leaving. I think the ambiguity about the several meaning of pressé is voluntary here.