There is a relatively simple dogma in a layperson's rules of biology concerning the difference in plants and animals. It is this: Plants make their own food. Animals do not. The resultant food chain or pyramid begins with food producers (plants) at the bottom and food consumers (animals) at all the layers above the producer layer. The difference between plant and animal is so categorically different, that they are organized by taxonomists into separate kingdoms...and there are only 5 (or 6) kingdoms of life. There is, of course, no overlap.
However, it really isn't that simple. First of all, there are plants out there that, in addition to using photosynthesis to make their own food, can capture and consume prey, albeit in a rudimentary fashion (some 630 species worldwide). Plants like the Venus Flytrap, Pitcher Plants, Flypaper Plants, Bladder Traps, Lobster-pot Traps, and other plants in a similar category (an additional 300 species) have evolved to flaunt such biological categorical dogma as the plant-animal divide. The existence of these plants proves that evolution by natural selection, one of the foundational laws of biology, knows no bounds or category and will capitalize on any naturally-existing phenomenon in order to gain some tangible advantage in survival. Although elm trees aren't hunting gazelles on some exotic savanna quite yet, the nature of these plants who behave like animals is nothing short of extraordinary. Want to know what is even crazier? You can OWN some of these plants as houseplants. That's right...you can flaunt biological dogma in your own living room.
