According to the evolutionary history of life on Earth and the available evidence suggests that life on earth began more than three and a half billion years ago. Today, the earth is home to more than 10 million different species. There are different forms of life around us, which range from small ants to the biggest whales, colourless worms and insects to brightly coloured flowers and birds. For ease of study and identification, the idea of biological classification was put forward. But for the relevant classification, a fundamental basis of classification is necessary.
Let’s learn about biological classification and basis of classification in details.
What is Biological Classification
Biological classification is the scientific procedure of arranging the organisms in a hierarchical series of groups and sub-groups on the basis of their similarities and dissimilarities. Many biologists have contributed to this method of classification, which took years for researchers to decide the most fundamental characteristics for the classification.
Basis of Classification
The history of biological classification began with Aristotle, the Greek philosopher, who is is often called the father of biological classification. He described animal classification based on their habitat i.e., air, water and land. He was the first person to recognize the need for groups and group names in the study of the animal kingdom.
Later, biologists started to work on the classification of living organisms based on their characteristics. Characteristics can be explained in many ways. A group of organisms are similar enough to be classified together by certain characteristics. Characteristics are the appearance/form and behaviour/function of something. These characteristics decide which organism will be in which group.
For example, a dog has limbs but a snake doesn’t. A dog and a snake can move but plants cannot. These are the characteristics of different organisms. These behaviours classify them into different groups. But which character should be the fundamental form or function? As per the above example, how should a dog be classified- whether on the basis of body design or its locomotion? Therefore this was not successful
In the mid-1700s, Carolus Linnaeus, a Swedish physician and botanist, published several books on different species of plant and animal. According to his discovery, he grouped the species according to their reproductive parts and developed the two-part binomial taxonomy system of categorizing organisms according to genus and species. This type of classification was effective. Later his work was combined with the work of Charles Darwin in the field of evolution to form the foundation of modern taxonomy.
Some of the characteristics which are used today to classify organisms are as follows:
- Prokaryotic or Eukaryotic cell.
- Unicellular or Multicellular.
- Autotrophs (Photosynthetic) or Heterotrophs (Non-photosynthetic).
- The level of organization and development of organs.
The fundamental characteristic to classify a plant and an animal is their body design. The next level of the hierarchy is, whether the plant is a tree or a shrub. Based on different characteristics, more subgroups will be formed.