Criteria in the Natural Classification of Animals Part II

As I said earlier in my Criteria in the Natural Classification of Animals I'm going to explain about Invertebrates.

Invertebrates

All other types of animals, other than the vertebrates come under this category. I'm going to classify them further. Invertebrates have been classified into phyla.

There are four main groups of invertebrates. They are:

1. Phylum Coelenterata.
2. Phylum Annalidae.
3. Phylum Molluscs (Mollusca)
4. Phylum Arthropods.

There are features, characteristics and adaptations endemic to each group of invertebrates. Below are those things.

1. Phylum Coelenterata.

• Has a radial symmetry.
• The coelenteron opens to the external atmosphere through a mouth.
• The body is made up of two layers of cells called Ectoderm skin and Endoderm Skin.
• The central gastro vascular cavity(coelenteron) system is lined by the endoderm.
• Some animals possess special cells(endoblasts) which contain poisonous substances which protect them.

Example: Hydra.

Hydra

2. Phylum Annalidae

• Worms with segmented bodies.
• Their bodies are made up of 3 layers.(tripoblastic). Outer Skin, Middle Skin, Inner Skin.
• The skin is covered by a cuticle.
• Possess hard bristles.
• Possess a coelem.

Example: Earthworm.

3. Phylum Molluscs (Mollusca)

• The body does not show any segmentation.
• The skin forms a mantle. This secrets a shell.
• The shell of the slug has disappeared.

Examples: Snail, Slug

4. Phylum Arthropods.

Invertebrate arthropoda

 

• Animals with segmented bodies.
• The body is bilaterally symmetrical.
• Have a strong exoskeletan.
• They adapt to the environment very quickly.
• Each body segment has a pair of appendages.
• Some appendages have formed the jaws.

Just finished explaining about 2 main categories of living beings - Plants, Animals. The remaining category is Micro-Organisms. Next article will be straightly about Micro-Organisms. So hope for it.! Good Luck 

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