What’s in a name? If you’re a taxonomist, a lot! This lesson will examine the classification system, focusing on the genus.
It will also explain how to recognize and write scientific names.
Definition of Genus
Let’s start this lesson by examining a picture. Take a moment and think about how you would sort, or classify, the organisms in this photo:
Here are some possibilities:
- Animals with legs and animals without legs
- Animals with backbones and animals without backbones
- Predatory animals and prey animals
There are scientists, called taxonomists, who work to sort or classify organisms based on similar characteristics, like you just did.
This classification system is continually evolving as new species are discovered. The broadest division is domain (there are only three) and species is the most specific (we don’t know how many species there are, but estimates are well over one million). Here’s a breakdown of the classification system that we’ll talk about in this lesson:
- Phylum (plural: phyla)
- Genus (plural: genera)
The classification of kingdom is very general and includes the animal kingdom or plant kingdom. In contrast, the division of genus is more specific as the grouping before species and after family.
If you keep studying biology, it is helpful to remember the order of the classification system by using a mnemonic device, or memory tool. Dear King Phillip Came Over For Great Spaghetti is one I have used to help me remember the order of the names of divisions.
Use of the Classification System
Let’s use that picture again to get a better idea of how classification works, focusing on the tiger. Here is the name for each grouping for the tiger:
- Domain: Eukaryota (this includes everything on earth except bacteria and archaea)
- Kingdom: Animalia (in fact, all of the critters in the photograph are in this kingdom)
- Phylum: Chordata (of the animals, the tiger is the only vertebrate animal)
- Class: Mammalia (this means the tiger, like you, is a mammal)
- Order: Carnivora (the tiger is a carnivore, or a meat-eater)
- Family: Felidae (he is a member of the cat family)
- Genus: Panthera
- Species: tigris
The scientific name for a tiger is Panthera tigris. There are some important things to note about scientific names that will help you in the future:
- Genus names are always capitalized and italicized or underlined.
- Species names are lowercase and italicized or underlined.
- Scientific names are the genus + species
Scientific names are usually Greek or Latin and they may look like nonsense, but if you know the meaning of the Greek or Latin word, they usually make sense. For example, Panthera comes from the Greek words ‘pan’ which means ‘all’ and ‘ther’ which means ‘prey’. Someone obviously thought that a fitting name for this genus would be ‘predator of all prey’. The species name ‘tigris‘ is thought to have originated the Persian or Iranian language and can be translated into ‘an arrow with speed towards a target’, probably because the tiger is a fast predator.
Grouping Species into a Genus
You might be asking yourself, ‘How do scientists know what organisms to group together in a genus?’.
Excellent question. Let’s keep using the tiger as an example. As mentioned earlier, tigers belong to the genus Panthera. Other members of this genus include the jaguar, the leopard, and the lion.
These four cats have been grouped into the same genus because they can roar and other members of the family cannot. They are not grouped into the same species, however, because they cannot interbreed, although tigers and lions have mated so you can see how the classification system can get a little sticky.Let’s use a red fox as another example, taking a look at each of the animal’s classifications. Everything is the same as the tiger for domain, kingdom, phylum, class and order.
Here’s the rest:
- Family: Canidae (dog family)
- Genus: Vulpes
- Species: vulpes
The scientific name for the red fox is Vulpes vulpes, which means ‘fox’ in Latin. All of the animals in the genus Vulpes share the following characteristics that set them apart from other members of the canidae (dog) family:
- They are small
- They possess flatter skulls
- They have black markings between their eyes
- The tip of the tail is a different color than the rest of the animal
There are 12 species within the Vulpes genus including the arctic fox, the bengal fox and the swift fox.
Organisms are classified based on similar characteristics. For instance, organisms within the order Carnivora eat meat and organisms in the genus Panthera can roar.
Understanding the classification and naming system helps you to understand different characteristics that same-grouped organisms share.An organism’s name can help you understand the classification system. For example, if you see a name that is capitalized and in italics, you know it’s a genus, the second most specific division within the 8-level classification system. A genus is more specific than a family, but less specific than a species. Scientific names are made up of the genus name followed by the species name.