crypt passwords?

Hi, I noticed that some MacPorts require, on Mac OS X, user accounts with cryptpassword types. For example, the OpenLDAP MacPort creates a user named ldap but interestingly the ldap user created is also created with a "crypt" password. Same thing for the Dbus (Message Bus) and PostgreSQL Server user accounts. Is there a reason why crypt passwords are used and should they be changed to a different type of password such as a Shadow Password? Thank you, T.M.