The Family name of the ocean stingray is "Dasyatidae"

The Family name of the river stingray is "Potamotrygonidae"

He has not family name.

The family name identifies one's family tree.

Japanese Emperor family is only and unique, so they don't need to have family name.

Last name is the name of the family-father's last name, or mother's last name. First name is the name given to certain member's of the family. For example: John Smith. Smith is the name of the family (father's family or mother's family). John is a specific member of the Smith family.

it is a family name. They are name for the 'family' who produces and sells them.

there is no family name for molybdenum!