In "The Trouble With Tribbles", we see people picking up and cuddling tribbles. There is special emphasis on them being warm and soft. Cyrano Jones trumpets "Tribbles have no teeth", though they somehow are capable of eating grain. They seem to have structure to their bodies, but they also seem almost featherweight.
Do all of this add up the tribbles being invertebrates? If they have no teeth, they likely have no bones at all. Since there is every reason to believe this species does not originate from Earth (The Enterprise crew act as if they had never seen or heard of these creatures) the definitions of animal lifeforms could differ from ours on some distant world.
Do all of this add up the tribbles being invertebrates? If they have no teeth, they likely have no bones at all. Since there is every reason to believe this species does not originate from Earth (The Enterprise crew act as if they had never seen or heard of these creatures) the definitions of animal lifeforms could differ from ours on some distant world.