Rules Question: Wolves of the Maelstrom

I'm starting an Apocalypse World 2nd Edition campaign and one of my players wants to be the Child-Thing from the extended playbooks. In the playbook it mentions the Wolves of the Maelstrom and they said they couldn't find any reference to the wolves in the rules, and neither could I. So are there any rules, guidelines, or explanations somewhere that I've missed? Or are they intentionally vague and are just malevolent antagonists left for us to devise completely?

Thanks for any help!

Intentionally vague, but it does say "Tell the MC that they are perversions of birth. They'll know what that means." Perversions of Birth is a type of Grotesque Threat. With that, their impulse (to overthrow, ruin, destruction of all), and the descriptions provided by the child-thing, you should have enough to work with.

Thanks apakalypse! That answered my question perfectly.