Classification

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Slide 9

The classification system that scientists use for naming species is hierarchical. It has seven major levels.

Kingdom: there are five of these - plants, animals, fungi, Protista and procaryotes

Phylum: the plural of this is phyla. Some examples of animal phyla are brachiopoda, chordata, and mollusca

Next is the Class. Some examples are Insecta (or insects), and mammalia (the mammals).

This is followed by the order. For example, humans and chimpanzees belong to the order of primates.

Next comes the family. Each order contains one or more families. Some families of primates include the Hominidae (hominids – which include the great apes and humans), and the lemuridae, which are the true lemurs. There are a total of 13 families of primates.

The genus is the first word of the two-word scientific species name. Each family is made up of a number of genera. For example, our genus is Homo.

Finally, we come down to the smallest level – the species. Our species is sapiens. A species is defined to be a group of living organisms that is capable of interbreeding to produce offspring that can also breed.

Slide 10

Let’s have a look at an example of classification of our species, Homo sapiens. We belong to the animal kingdom, and the phylum of chordates – the animals with a backbone. Our class of chordates is the mammals – this means we have fur or hair and milk glands. The order of mammals that we , along with the chimpanzees and monkeys belong to is the primates, and the family of primates we belong to are the hominids. Like other hominids we have relatively flat faces and three-dimensional vision. Now, for most of our lives, we’re able to stand upright and our brains are really big. These are characteristics we share with all members of the genus Homo. Finally, we have a high forehead, and thin skull bones. We also have a bigger brain than many other members of the genus Homo. We belong to the species Homo sapiens.

Slide 11

The biggest class of organisms is the kingdom. There are five of these - plants, animals, fungi, Protista and procaryotes. The kingdom that an organism belongs to depends on a number of factors including the way in which they obtain their food, whether they can move around on their own, the types of cells that make up their bodies, and the number of cells in their body.

Slide 12

The Five kingdoms are the Monera (or Prokaryotes), the protists, the fungi, the plants and the animals. We know what plants and animals are, but we’ll now go into details about the sorts of organisms that belong to each of these five kingdoms.

Slide 13

The Monera kingdom (or the Prokaryotes) is made up of single-celled (or unicellular) organisms. These organisms consist of single cells that do not contain a nucleus.

Some examples are bacteria and blue-green algae. You’re probably wondering about viruses at this point. Viruses don’t actually belong to any of the five kingdoms. In fact, scientists don’t really think viruses are living things – they don’t eat, and they don’t produce waste. The only property they have in common with organisms is that they can reproduce… and they really require another living thing to do this for them.

Slide 14

Protists are also single-celled organisms, but they’re eukaryotes, so they have their own nuclei, and they are highly organised cells. They have moving parts like Flagellae and they can move around within their environment. Some examples of protists are single-celled algae and protozoa.

Slide 15

Fungi like mushrooms, toadstools and lichens have been put into their own kingdom because they are unlike any other organisms. They can’t make their own food. Instead, they absorb their nutrients from their environment. For example, fungi might live on decaying wood.

Slide 16

Surprisingly enough, all plants belong to the plant kingdom. Some examples of plants are trees, grass, flowers, and ferns. Multicellular algae and seaweed are also
Plants. The defining characteristic of plants is that they can make their own food using water and sunlight, in a process called photosynthesis. This is why fungi are not characterised as plants: they can’t make their own food.

Slide 17

All members of the animal kingdom are multicellular. They get their food by eating other organisms – either plants or animals or both. This is the largest of all kingdoms
And includes everything we think of as animals: birds, mammals, reptiles, fish, insects and so on. We are members of the animal kingdom.

Slide 18

Each kingdom is divided up into a number of phyla. Members of each phylum exhibit some kind of physical similarity. Some examples of animal phyla are brachiopoda, chordata, and mollusca. Phyla can only contain members of a single kingdom.

Slide 19


There are nine major animal phyla, but there are actually 36 recognised animal phyla. We belong to the phylum chordata. This phylum includes all vertebrates (animals with a backbone) and all animals with some sort of nerve chord. Let’s look at some examples of animals in the other phyla. The phylum Echinodermata includes sea stars and sea urchins. Phylum mollusca includes molluscs like snails, squid and claims. Phylum Arthropoda includes insects, spiders and crayfish. In phylum Annelida, we have the earthworms and leeches. Roundworms are included in phylum nematoda. Flukes, tapeworms and planarians are members of phylum platyhelminthes, which Cnidaria includes jellyfish, corals and anemones. Finally, phylum porifera includes sponges.

 
Slide 20

Each phylum is divided up into two or more classes. The organisms in a class have more in common than the organisms in a phylum. For example, we belong to the class
Mammalia of the phylum chordata. Some other members of that class are kangaroos, horses, cows and elephants. These species have more in common with each other – for example fur or hair and feeding their young with the milk they secrete than they have with birds, which are members of the aves class of chordata.

Slide 21

Each class is further broken down into orders. Members of an order have more in common than members of a class. We belong to the order primates of the class mammalia. We have much more in common with other members of the primate class such as monkeys and chimpanzees than we have with other mammals such as bats.

Scientists use a taxonomy key to determine the order that an individual organism belongs to. Such keys often consist of a series of questions with two possible answers,

And are called dichotomous keys. For example, these questions might be things like: does the organism walk on two or four legs? Answers ‘yes’ to this, and a series of other questions are used to assign the organism to the class primate.

Slide 22

We further divide each order up into a collection of families. Again, members of each family have more in common with the other organisms in classification levels above families. Some examples of families within the class primates are hominids and the lemuridae (or lemurs). We belong to the class hominids and have much more in common with other hominids than we have with lemurs.

Slide 23

The genus classification is even more specific. IT provides the first (generic) part of the scientific name of the organism. Each Family contains many different genera.
We belong to the genus Homo, and Homo forms the first word of our two word scientific species name: Homo Sapiens. The Orca belongs to the genus Orcinus. Its scientific name is Orcinus orca.

Slide 24

Finally, we have the smallest possible classification. The species. Each order includes a number of different species. This is the strictist classification of animals. Organisms in the same species can breed with each other to produce offspring that can also breed with each other. We belong to the species sapiens of the genus Homo. Some other (past) species from the genus Homo are erectus and neanderthalis.

Slide 25

That’s all we’ll say about classifying organisms for now. In the next presentation, we’re going to have a further look at classification and the ways in which scientists assign different organisms to different groups using classification keys.