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Biology · Class 9-10 · Chapter 1 · 1.3

The five kingdoms.

Of all the living things on earth, Whittaker put every one into five kingdoms in 1969. The division was not arbitrary; he looked at three things, the build of the cell, the build of the body, and the way food is got. This note has one aim, and it is not to have you learn five names by heart. It is to leave a method in your hands, so that meeting any living thing you can work out its kingdom yourself.

1. The deepest line of all

Before going into the five kingdoms one line has to be drawn, because it is the oldest and the deepest of them. Either a cell has a proper nucleus in it or it has not. If it has, the cell is eukaryotic; if it has not, it is prokaryotic. Drag the handle and put the two side by side.

two cells drag the handle

With a nucleus, and without

a prokaryotic cell
a eukaryotic cell

In the cell on the left there is chromatin, but no membrane around it and no nucleolus; no plastids, no mitochondria, no endoplasmic reticulum either. What there is: ribosomes, and a cell wall outside. In the cell on the right there is a nucleus bounded by its own membrane, a nucleolus inside it, and organelles such as mitochondria and endoplasmic reticulum around it. That one difference is enough to cut the five kingdoms in two.

2. The five, in one table

The three things Whittaker looked at, the book sets out as four questions: what kind of cell, whether there is a wall and what it is made of, how food is got, and whether the body is one cell or many. Ask those four of all five kingdoms at once and the whole section fits in a single table.

grid tap a row or a cell

Five kingdoms, four features

Kingdoms down the side, features across the top. Tap a kingdom for the whole of it, or a cell for that one feature.

kingdom cell wall food cells
Monera prokaryotic yes absorbed one
Protista eukaryotic in some all three one
Fungi eukaryotic chitin absorbed only one or many
Plantae eukaryotic cellulose made by it many
Animalia eukaryotic none swallowed many
Monera. Prokaryotic: no proper nucleus, chromatin but no nucleolus and no nuclear membrane. No plastids, no mitochondria, no endoplasmic reticulum; ribosomes, yes. There is a cell wall. The body is one cell, or a thread of them, or a colony. Food is absorbed, and some of them photosynthesise as well. They multiply chiefly by splitting in two. Examples: bacteria, and the blue green algae.

3. Two super kingdoms

In 1974 Margulis set Whittaker's five kingdoms under two super kingdoms. Notice that he did not change their number; the five stand as they were, with two umbrellas over them. What the umbrellas rest on is that line about the nucleus.

a tree tap to open

Two super kingdoms, five kingdoms

  • the living world
    • Super kingdom: Prokaryota
      • Kingdom 1 · Monera
        • bacteria, blue green algae
    • Super kingdom: Eukaryota
      • Kingdom 2 · Protista
        • amoeba, paramecium, euglena
      • Kingdom 3 · Fungi
        • mushroom, penicillium, yeast
      • Kingdom 4 · Plantae
        • mango, jackfruit, rice, water lily
      • Kingdom 5 · Animalia
        • hilsa, rui, tiger, cockroach

Notice that one super kingdom holds a single kingdom and the other holds four. The division is not equal in number; it is equal in weight. Whether there is a nucleus is the deepest difference in the living world.

4. A key to the kingdoms

This is exactly how a taxonomist works: one two way question after another. There are four questions in the key below, and each of them stands on the answer to the one before it. Pick a living thing, then answer.

the key pick one, then answer

Working out a kingdom

5. Now sort them yourself

Reading a table and using one are two different things. Among the ten below there are two traps. The blue green algae photosynthesise and are not plants; the mushroom neither moves nor lacks a wall, and is not a plant either. Work out why before you begin.

sort them a chip, then a kingdom

Which kingdom is home

Pick up a chip, then drop it in a kingdom. The question is the same every time: the cell, the wall, the food, the number.
cards turn a card

Each one in a line

kingdomMonera
how to know itThe one prokaryotic kingdom; no proper nucleus. No plastids and no mitochondria either, but ribosomes there are.
kingdomProtista
how to know itEukaryotic and yet mostly single celled, and all three ways of feeding are found in it. No embryo is formed.
kingdomFungi
how to know itThe wall is chitin, and the food is only ever absorbed, from what is dead or from what is alive.
kingdomPlantae
how to know itA wall of cellulose and chlorophyll, the two together. Many celled, it makes its own food, and an embryo is formed.
kingdomAnimalia
how to know itNo cell wall at all. The food is swallowed; the embryo has three layers, ectoderm, mesoderm and endoderm.
two umbrellasThe two super kingdoms
Margulis, 1974Prokaryota: Monera and nothing else. Eukaryota: Protista, Fungi, Plantae and Animalia.
check yourself

One question

In which kingdom is the cell wall made of chitin?

check yourself

Another question

The blue green algae make their own food in the light. Why are they not put in Plantae?

check yourself

Last question

A living thing has a proper nucleus, a many celled body with tissues, a cell wall, and no chlorophyll. Which kingdom?

At a glance

The bases. The build of the cell, the build of the body, and the way food is got; Whittaker, 1969.

Two umbrellas. Prokaryota holds Monera alone; Eukaryota the other four; Margulis, 1974.

The wall. Monera has one, Fungi's is chitin, Plantae's cellulose, Animalia has none.

The rule. No single feature settles a kingdom; the features have to be taken in their order.

Source: Biology, Classes 9-10 (NCTB), Chapter 1 “The study of life”, section 1.3, the part on the living world.