Kingdoms

Within the domain Eukarya, life is generally organised into four discernible kingdoms. Three of these—Animals, Plants, and Fungi—will be familiar to most people.

Kingdom Common Group Key Characteristics

Animalia Animals Multicellular eaters like birds, mammals, insects, and arachnids.

Plantae Plants Photosynthetic life: flowers, mosses, ferns, conifers, and grasses.

Fungi Fungi & Lichens Absorptive feeders with chitin cell walls (mushrooms and lichens).

Protista* Protists The "Rule Breakers" such as Slime Moulds.

The Fungi Misconception

It is a common mistake to think that because fungi have stems (stipes) and a "flower" (the cap), they are plants. In reality, fungi are a totally different life form and actually have more in common with animals than plants! 

The "Junk Drawer": Protista

Kingdom Protista was traditionally used for anything that didn't fit elsewhere, like algae or amoebas. However, modern DNA evidence shows that some "protists" are more related to animals than to other protists. While scientists now prefer to use "Supergroups" (like Amoebozoa), using "Kingdom Protista" is still a valid way for us to group fascinating organisms like Slime Moulds away from plants and animals.

A Look Inside the Microscopic Kingdoms

While the "Kingdom" label is very clean for animals and plants, it gets "messy" when we look at the Domain Bacteria. Historically, all bacteria were in one kingdom called Monera, but that name has been retired. If we used the same "distance" we use to separate plants from animals, the Bacteria domain actually contains dozens of kingdoms.

Group Why they are famous Examples

Cyanobacteria They "invented" photosynthesis and gave our atmosphere oxygen. Blue-green algae.

Proteobacteria The ancestors of the mitochondria in your own cells. E. coli and nitrogen-fixing soil bacteria.

Firmicutes Known for "tough" cell walls; many live in your gut. Lactobacillus (in yogurt)21.

Actinobacteria The "Earth-smellers" that produce the "fresh rain" scent. Producers of most medical antibiotics.