Classification of organisms
“If you are not willing to learn, no one can HELP you! If you are determined to learn, no one can STOP you!” – Unknown
HELLO MY fellow learners, how are you this week? I hope everything is now falling into place for you and you are well on your way to achieving that oh-so-elusive grade one.
This week, we will be revising one of the topics that you did in your first year of high school. We will be revising because, as you and I know, memories are not what they used to be! What is this topic? It is the classification of organisms.
Classification is a part of everybody’s life. Book stores classify books according to their genre, fiction, non- fiction, science fiction, romance, mysteries, etc, while music stores may have their music classified as classical, jazz, popular, reggae, dancehall, etc. Supermarkets also have a system of classification. Apart from the obvious grouping, they also group items in such a way that their placing will appeal to our subconscious and, without realising it, we buy! A classification system helps both the owner and the shopper to find/identify items easily. In science, a classification system is needed to provide order and method in the study of living organisms.
We have been talking about classification systems, but what exactly is classification? A simple definition is as follows:
‘Classification is the grouping of things on the basis of features that they have in common’.
THERE ARE TWO MAIN TYPES OF BIOLOGICAL CLASSIFICATION SYSTEMS
Artificial – Organisms are placed in groups for convenience. The placing in groups does not have any bearing on true relationships or evolutionary patterns.
Natural – Organisms are placed into groups based on their natural relationships. Both internal and external features are used to place the organisms into groups.
We will be concentrating on the natural system of classification. First, here are the definitions of some words that you may encounter while reading up on this topic: Systematics – The study of biological diversity. Taxonomy – The study of the principles and methods used in biological classification.
Nomenclature – The naming of biological groups.
Taxa (singular taxon) – A series of groups arranged in a hierarchy.
Biologists use what is known as the five kingdom classification. In this, all organisms are divided into five large groups that are called kingdoms. These are Prokaryotae (bacteria and blue-green algae), Protoctista (protozoa and algae), Fungi (yeasts, moulds and mushrooms), Animalia (animals) and Plantae (plants). Each kingdom is divided into seven main groups. These are, in descending order: Kingdom, Phylum, Class, Order, Family, Genus and Species. In the classification of plants, Phylum is replaced by Division. The group comprising the largest number of organisms is Kingdom and the one with the smallest group is the species. It means that the organisms included in the species are more closely related to each other than to the rest of those included in the Kingdom.
Every organism is given a scientific name of two words. The first begins with an upper-case letter and is the generic name (from the genus) and the second begins with a lower-case letter and is the specific name (from the species). In your text, you will notice that all scientific names are written in italics, e.g., Homo
sapiens; if you are writing them, they must be underlined, for example, Homo sapiens. This system of naming is known as the binomial system.
Let us look at an example of the classification of two animals, for example, man and dog.
See you next week!
Monacia Williams is an independent contributor. Send questions and comments to firstname.lastname@example.org
Did you notice that man and the dog share the same kingdom, family and class, meaning that they have enough features in common to allow them to share these?
Let us look now at a plant.
Did you notice anything significant about this table? Our national tree, the Blue Mahoe, and the hibiscus plants are very closely related. Both belong to the genus, Hibiscus! Interesting, isn’t it?