The party members are listed in the inventory menu, along with guns and hats. At first, it may seem weird, until you realize that the crew are all steambots, and despite being sentient, consider themselves materiel (and can be rebuilt if they "die" in battle).
This might also explain why Piper and Seabrass are seemingly apathetic about their dead crewmates, acting inconvenienced more than anything else. This was especially jarring given Piper generally treats her crew like family
