Classification of Organisms
Tuesday, April 9, 2013
Sunday, February 24, 2013
Part two
Animals
The main feature on which animals are classified is the presence or absence of a vertebral column.Considering this characteristic, animals are divided into two main groups :- Invertebrates
- Vertebrates
Invertebrates
The main phyla among invertebrates are as follows :- Phylum 1 : Coelenterata
- Phylum 2 : Annelida
- Phylum 3 : Mollusca
- Phylum 4 : Arthropoda
Phylum 1 : Coelenterata
Based on body structure, these organisms are of 2 types - Polyp form
Medusa form
Main features :
Possesses a soft body.
Jelly fish |
Diploblastic body ( http://en.wikipedia.org/wiki/Diploblasty)
Incomplete alimentary canal with only one opening.
Lives in water.
Has a sedentary life style.
Examples : Hydra, Jelly fish, Sea anemone, Polyp corals
Sea anemone |
Hydra |
Polyp corals |
Phylum 2 : Annelida
Main features :
Metameric segmentation (http://en.wikipedia.org/wiki/Metameric)
Leeches |
Are of several sizes
Some are parasitic & lives in host bodies
Triploblastic body (http://en.wikipedia.org/wiki/Triploblastic)
Has bilateral symmetry
Possesses a coelom (Body cavity containing fluid)
Possesses hard bristles called chaeta (Except in leeches)
Examples : Leech, Earthworm, Rag worm, Flat worms, Round worms
Earthworm |
Flatworm |
Rag worm |
Octopus |
Main features :
Triploblastic body.
Unsegmented.
Soft, wet & slimy body.
Has bilateral symmetry.
Possesses a coelom.
Have well-defined circulatory, respiratory, excretory & digestive systems.
Body comprises 3 parts :The Head
Ventral Mascular Foot
Dorsal Visceral Hump (Mantle)
Some have sensory tentacles.
In some mollusca, the body has an outer shell for protection, made of Calcium Carbonate.
Clams |
Cuttlefish |
Snail |
Phylum 4 : Arthropoda
This phylum contains more species than any other phyla.More than 3/4 of all known species of animals are arthropods.The most abundant arthropods are insects.
Main features :
Possesses joint appendages- These are more elaborate & specialized than in annelids.
Shows clear metameric segmentation.
Dragonfly |
Triploblastic body.
Coelomate.
Has bilateral symmetry.
Lives in water as well as land.
Examples : Scorpion, Butterfly, Dragonfly, Cockroach, Prawns, Millipedes, Ticks
Arthropods |
Part one
Introduction
There are millions of organisms living on Earth. These organisms differ in shape, size, structure, e.t.c. When studying such a vast biodiversity, the necessity of classification emerged. According to Robert H. Vitaker's 5-kingdom classification, organisms were classified into:
- Monera
- Protista
- Fungi
- Plantae
- Animalia
In this blog, organisms are classified under 3 main groups:
- Plants
- Animals
- Micro-organisms
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