An often used tool on UNIX is ldd, but that doesn’t exist on Mac - however I just found out that there is otool which can do the same thing:

martin@vaccine$ otool -L /usr/bin/curl
/usr/bin/curl:
    /usr/lib/libcurl.4.dylib (compatibility version 7.0.0, current version 8.0.0)
    /usr/lib/libz.1.dylib (compatibility version 1.0.0, current version 1.2.5)
    /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1213.0.0)