Animal classification :
- Formation of groups and sub-groups of animals depending upon similarities and differences among animals.
History of animal classification :
- Aristotle was the first to perform the animal classification.
- Classification proposed by Aristotle is known as ‘Artificial method’.
- Besides Aristotle, artificial method of classification was followed by Theophrastus, Pliny, John Ray, Linnaeus, etc.
- System of classification based on evolution was used by Dobzhansky and Meyer.
- Recently, Carl Woese has also proposed the animal classification.
Benefits of animal classification :
- Convenient study.
- Study from a group helps to understand about that entire animal group.
- Gives idea about animal evolution.
- Animals can be easily identified with great accuracy.
- Helps to understand the relationship of animals with other living organisms.
- Helps to understand the habitat of each animal and it's exact role in the nature.
- It helps to understand various adaptations shown by animals.
Traditional method of animal classification [Depending upon presence or absence of the notochord ]:
- Non-chordates
- Chordates.
- Body is not supported by rod-like notochord.
- Pharyngeal gill-slits are absent.
- Nerve cord; if present, it is on ventral side. It is solid & paired.
- Heart, if present, it is on dorsal side.
B. Chordates :
- Body is supported by notochord.
- Pharyngeal gill-slits or lungs are present for respiration.
- Nerve cord is present on dorsal side of body. It is hollow.
- Heart is present on ventral side of body.
Notochord :
- Long rod like supporting structure
- Present on dorsal side of animal body.
- Keeps the nerve tissue isolated from remaining body.
- At present, according to the five kingdom classification system of Robert Whittaker, all multicellular animals are included in Kingdom: Animalia.
- This system of classification is based upon some criteria like
- Body organization
- Body symmetry
- Body cavity
- Germinal layers
- Segmentation, etc.