Can we use uncountable noun with plural verb?

Question

I found this passage from a test.

The typical way in which the piranha attacks is by swimming directly into a shoal of fish. The attacked shoal scatters in all directions, and the piranha quickly overpowers individual fish. Small fish are swallowed whole. Larger prey have chunks ripped out of them, which the piranha swallows instantly so it can immediately take another bite.

I wonder why “prey” can be used with “have” since “prey” is uncountable noun.

And the answer key tells that “them” refer to “larger prey”. Why don’t we use “it” to refer to “large prey”?

I’m not sure if all of this passage is correct. And for that sentence I think it should be “Larger prey has chunks ripped out of it.” Could you explain it to me?

Answer 1

Quote: My dictionary says prey is an uncountable noun.

I would say take such indications as a general hint. Nevertheless a writer can choose whether he wants to use that word as a collective noun with a singular verb or as word with plural meaning in the sense of all the animals that are prey. In this respect - countable or uncountable - English is flexible and tolerant. You will find this flexibility with almost all nouns that are collective nouns for groups. You can use "police" as a singular when you think of the whole of that organisation and you can use it as a plural noun when you think of the lot of people in the police force.