Biodiversity and Biological Classification

This is a great video to show to your students as a hook into biodiversity. Before we can tackle the classification of species on Earth, we should introduce our students to  the great variety of life on Earth.


Biodiversity is the number and variety of species and ecosystems on Earth. It speaks to the essential interdependence of all living things. This tremendous variety of life on Earth if made possible by complex interactions among living things. Everything on this planet is connected and the loss of one could be disastrous for the others. Scientists have identified more than 2 million species but tens of millions remain unknown. Unfortunately, we are losing our biodiversity and scientists are scrambling to save it. We now have ‘biodiversity hot spots’ which are areas on the planet that contain species that exist nowhere else on Earth. If we were to lose one hot spot, the species that live in that area would be completely extinct. These areas are protected and many of them are in rain forests.

dolp tree


Species are ›all organisms capable of breeding freely with each other under natural conditions. This means that they can produce offspring that breed. If we look at the example of a mule, two members of different species create an offspring that is sterile. Ligers are another example of two members from different species breeding to produce offspring that cannot breed.


Biological Classification

Biological classification is the systematic grouping of organisms into biological categories based on physical and evolutionary relationships. An example of this is scientists grouping organisms into sections like: producer,  herbivore,  predator and scavenger.



Taxonomy is the science of classifying all organisms. Taxonomists classify both living and fossil species. Taxonomy is also referred to as the “Science of Systematics”. With millions of species living on Earth, and countless extinct species, you can see how taxonomy can be a challenging science!

Early Classification Systems (Carl Linnaeus)

Carl Linnaeus was an 18th century Swedish scientist who is known as the ‘father of taxonomy’. Linnaeus started his classification process by distinguishing between plants and animals according to similarities in their form. He concluded that the more features organisms have in common, the closer their relationship must be. He designed a system in which each organism is given two names. He called this binomial nomenclature and his classification system is still used today. Linnaeus wrote a book in 1735 called ‘Systema Naturae’ in which he grouped species and genera into order, classes and kingdoms.

Binomial Nomenclature

Binomial Nomenclature is the formal system of naming species whereby each species is assigned a genus name followed by a specific name; the two words together form the species name.


taxon is a category used to classify organisms. A kingdom is the highest taxonomic level of the traditional Linnaean system of classification. Genus is a taxonomic level consisting of a group of similar species.


Ex.1 Salmo    salar    Atlantic Salmon

Ex.2 Salmo    trutta   Brown Trout


Caution: The species name will always INCLUDE the genus!

Levels of Classification


This chart shows how the taxa go from very general characteristics to the most specific classification of species. Originally there were 8 levels of classification but now we have added a new level above kingdom called domains.
Student Activity: Have students work in groups to create an original acronym to represent the levels and order of classification. One example is ‘Desperate King Philip Came Over For Green Spinach’. This is a nice time for students to be creative and making acronyms helps with consolidation of information. Give students some chart paper and markers and tell them to use appropriate language.

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