the science calorie (little c) is a measure of heat energy the food calorie (big C) is a measure of energy that we burn, but it is equal to 1,000 science calories so 1 big C is equal to 1,000 little c's.
Protists are a group made up of protozoa, unicellular algae, and slime molds. We will concentrate on the animal portion of this group: the protozoa (proto = first, zoa = animals).
Phylum Protozoa. Paramecium, A Unicellular Animal. There's no doubt about it that the earliest forms of life were simple unicellular organisms and in that respect protozoans must be considered the earliest animals. Many of these have survived the longest geological periods with very little change.