An animal was a multicellular lifeform of the kingdom Animalia in biology. In normal conversation, it was used to refer to a non-Sapient member of that kingdom. Unlike plants, animals could not make their own food energy, and unlike the more closely related fungi, digestion took place internally, rather than externally.
On Betazed, women used to wear huge wigs with large holes in the middle where cages for tiny animals were kept. This fashion was very cruel for the animals and was abolished after many years. (TNG: "Half a Life")
The emotions of animals could be felt by telepathic species, such as Betazoids detecting the emotions of sentient beings. (TNG: "Pen Pals") Vulcans could communicate with animals, at least with highly intelligent species. (Star Trek IV: The Voyage Home)
- See Invertebrate