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| Phylum Arthropoda |
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| This phylum is the largest in the animal kingdom comprising of more than 75% of the animal species that have been identified. |
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 Free living forms, aquatic (fresh water or marine) or terrestrial or aerial. Some parasitic forms also. |
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 Body is elongated and segmented, usually distinguished into regions like head, thorax and abdomen. |
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 Body has exoskeleton made up of a hard, impermeable substance called chitin. |
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 Digestive system is complete. |
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 Circulatory system is of open type. Blood flows freely in the body cavity (hemocoel). |
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 Respiration through gills, or trachea or book lungs. |
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 Excretion through coxal glands or malpighian tubules. |
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 Nervous system consists of a nerve ring and a double ventral nerve cord. |
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 Locomotor organs represented by segmentally arranged many jointed appendages. |
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 Cilia are totally absent in any part of the body. |
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 Reproduce sexually, sexes are separate. Development may be direct or indirect. |
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| fig.10.16 - Examples of Arthropoda |
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| The phylum is divided into six classes |
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| fig.10.17 - Grasshopper Anatomy |
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