Cleon
Legend
Because every other monster with a sunderable tentacle I can find in the SRD loses half the tentacle's hp when the tentacle is sundered. Even hydras do that. A roper's strands do seem to be the exception (no damage), but strands are very thin and don't seem precisely to be part of a roper's body the way a tentacle would be.
An udoroot has "crowns" with 7 hp apiece and takes no damage if one is severed.
I'd much rather a Walking Wonder and take no damage on sundering than increase the hp to 2 so you feel better about it suffering 1 damage if it loses a tentacle.