There are sharks that do it for the team ("our shark"), and there are sharks that do it entirely for themselves.

The latter are dangerous, you can't ever trust them.

If there's ever an edge, a personal benefit to be had from going against the team, they might take it.

The former you can trust as long as the shark thinks you're on the same team.

But watch out, because if they ever come to believe the group they're part of is not relevant to them, they'll be a danger to the group.