More than one and a half million species of organisms are known. To obtain an overview these organisms are ordered, that is to say; they are divided into groups with the same characteristics. These groups are increasingly broken down into smaller groups with certain similarities. Of course, many different classifications are possible and opinions continue to differ. In this article a simple classification of the animal kingdom, based on examples.
Rich
Example: Animal kingdom
Organisms are classified into four ‘realms’: the realm of bacteria, the realm of fungi, the realm of plants and the realm of animals. This first classification looked at the characteristics of the cells of organisms: the cell nuclei, the cell walls and the leaf green granules.
- Bacteria: no nucleus, no leaf green granules, but a cell wall
- Fungi: cell nucleus, no leaf green granules, but cell wall
- Plants: cell nucleus, leaf green grains, cell wall
- Animals: cell nucleus, no leaf green granules, no cell wall
Departments
Example: Vertebrates
So all organisms in the animal kingdom have something in common. Their cells are distinct from the cells of organisms in the other realms; they do not have a cell wall.
The animal kingdom is again divided into different sections. This classification looked at the skeleton; internal, external or no skeleton, and to symmetry. Many kinds of animals are symmetrical on both sides; humans, for example. These types can only be divided into two (approximately) equal halves in one way. Other types are versatile symmetrical; a starfish, for example, can be divided into two equal halves in several ways. There are also types that cannot be divided into equal halves, these types become non-symmetrical called, such as the slipper animal. The eight divisions in the animal kingdom have the following characteristics:
- Unicellular animals: non-symmetrical, no skeleton, example; slipper animal
- Sponges: non-symmetrical, internal skeleton (horn fibers between cells), example; bath sponge
- Cavity animals: versatile symmetrical, no skeleton, example; jellyfish
- Worms: symmetrical on both sides, no skeleton, example; earthworm
- Molluscs: bilaterally symmetrical, external skeleton (house or shell), example snail
- Arthropods: bilaterally symmetrical, external skeleton (armor), example crab
- Echinoderms: versatile symmetrical, internal skeleton, example starfish
- Vertebrates: bilaterally symmetrical, internal skeleton (spine), example human
Classes
Example: Mammals
The divisions in the animal kingdom are again divided into different classes. Vertebrates, for example, are divided into five different groups. This classification is based on the skin, body temperature, respiratory organs and mode of reproduction.
The vertebrates are divided into the following classes:
- Fish: cold-blooded, gills, shellless eggs, skin covered with scales and mucus
- Amphibians: Cold-blooded, lungs, eggs without shells, skin covered with mucus
- Reptiles: Cold-blooded, lungs, leathery-shelled eggs, skin covered with dry scales
- Birds: warm-blooded, lungs, eggs with scale, skin covered with feathers
- Mammals: Warm-blooded, lungs, viviparous, skin covered with hair
Order
Example: Predators
The mammalian class still consists of more than five thousand animal species. They are warm-blooded, have lungs, fur and they suckle their young with mother’s milk. These are some common features, but the differences are also many. For example, there are mammals that fly, swim, eat meat or eat plants. The classes can thus also be divided into smaller groups, which are called ‘orders’. For example, the class of mammals is divided into some thirty orders, including that of the bats, the whales, the predators, the rodents, and the primates.
Families
Example: Felines
If we choose from all those orders of mammals, for example, ‘the order of the predators’, we are faced with even smaller groups that are referred to as ‘families’. The order of predators consists of about fifteen families. . Most predators eat meat. But whether they also eat plant foods and how they are equipped for hunting differs from family to family. For example, you have the family of the felines, the canids, the mustelids, the bears and the hyenas.
Genders
Example: Panthers
Smaller groups of animals within the different families are called “genera.” Within the family of the felines, the sexes of lynxes, cougars and panthers can be distinguished.
Species
Example: Leo
Our house cat and lion are of course family (felines), but they are ‘species’ belonging to different sexes. The domestic cat belongs to the genus ‘felis’ just like the wild cat and the desert cat, while the lion belongs to the genus ‘panthera’ as well as the tiger and the jaguar. Animals belong to the same “species” if they are capable of mutually reproducing and the offspring are fertile.