How are animals classified?
One among many parameters to classify animals is to classify them based on a notochord (backbone or vertebral column) of the animal body.
Based on the presence or absence of a notochord, animals are classified into non-chordates, hemichordates, and chordates.
What are the different types of animals based on the presence or absence of a notochord?
- Non-chordates
Non-chordates are the lower animals which do not possess a proper notochord. They include various phyla like:
- Porifera
- Coelenterata
- Platyhelminthes
- Nematodes
- Annelids
- Arthropods
- Echinodermata
- Mollusca
(ii) Hemichordates
These organisms have a notochord but only for a specific period of their life cycle.
The embryonic stages show a notochord-like structure, but the adult forms are like invertebrates, without a notochord.
(iii) Chordates
These organisms have a characteristic notochord, the vertebral column. The phylum Chordata has a few more subphylum like:
- Urochordata
- Cephalochordata
- Vertebrata
The subphylum Vertebrata is comprised of classes like:
- Agnatha
- Pisces
- Amphibia
- Reptilia
- Aves
- Mammalia
Classification of kingdom Animalia