Hello I have a question about DOF

Hello I’m Kwang hee Han, student in Korea. I watched video on youtube and the link is below.
youtube.com/watch?v=0jyBiECoS3Q
and I have a question about DOF. It is mentioned that
[font=Roboto, arial, sans-serif][highlight=#ffffff]“A-Pod is an ant inspired hexapod robot with a 2 DOF abdomen (tail), a 3 DOF head with large mandibles. 6 legs with 3 DOF each. Total 25 servos”[/highlight][/font]
[font=Roboto, arial, sans-serif][highlight=#ffffff]
[/highlight][/font]
[font=Roboto, arial, sans-serif][highlight=#ffffff]Why does it uses 25 servos instead of just 23 servos?[/highlight][/font]
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[/highlight][/font]
[font=Roboto, arial, sans-serif][highlight=#ffffff]I’m looking forward for you to answer this question.[/highlight][/font]
[font=Roboto, arial, sans-serif][highlight=#ffffff]Thanks a lot and have a nice day:)[/highlight][/font]

]6 legs = 18 Dof./:m]
]Head = 3Dof (pan, tilt and roll)/:m]
]Mandibles = 2 servos/:m]
]Tail = 2 servos/:m]
Total = 25 servos.

thanks a lot!
but what I wanna know is actually why it uses 25 motors even though the DOF is 23.
looking forward to you apply:)

The mandibles don’t really count as “degrees of freedom” since they don’t affect the motion.
For example, a robot arm might be classified as 6Dof or 5Dof depending on if you count the servo in the gripper.